KAVACH (IRATP) - Automatic Train Protection (ATP) System

RFID Tags in KAVACH System

Today, we’ll be discussing RFID Tags in the KAVACH System. KAVACH is Indian Railways’ Train Collision Avoidance System, and RFID tags play a vital role in ensuring location accuracy and safe operation.

Introduction to RFID System

An RFID system consists of two key components: tags and readers.
The RFID tag has a chip that stores data and an antenna for communication. The reader generates an RF signal and receives data from the tag.
In KAVACH, tags are installed on the track — both in station sections and block sections — while the readers are mounted on the locomotive units. Together, they form the foundation of safe train control.

Working Principle

Each locomotive equipped with KAVACH has two RFID readers for redundancy.
When the loco passes over a tag, the tag transmits its stored data to the reader.
This data includes crucial information such as location and operational details.
Tags are always installed in duplicate pairs. The data stored is identical except for the unique ID and exact location, ensuring reliability even if one tag fails.

Types of RFID Tags

RFID tags are broadly classified as passive or active.

• Passive tags don’t have their own power supply. They rely on the signal from the reader to get activated.

• Active tags, on the other hand, come with an internal battery and can transmit over longer distances at higher data rates.

In KAVACH, we use passive tags because they are more cost-effective, maintenance-free, and perfectly suitable for trackside applications.

Read-only vs Read/Write Tags

RFID tags are also categorized by how data is stored:

• Read-only tags contain data written during manufacturing. This cannot be changed.

• Read/Write tags allow data to be updated or erased as required.

For KAVACH, we use read/write tags, because they allow operational flexibility and updating of information when needed.

Technical Specifications

Now let’s look at the technical details:

• The RFID tags in KAVACH operate in the UHF band, between 865 and 867 MHz.

• They are reliable even at train speeds up to 250 kilometers per hour.

• The onboard KAVACH system determines the train’s location by combining RFID tag data with inputs from a directional speed sensor.
  This ensures precise train positioning even at high speeds.

RFID Tag Fixing Arrangement

RFID tags are installed at the center of PSC sleepers.
It’s important to note that no holes are drilled in sleepers. Instead, we use clamps for fixing to maintain sleeper strength.
The fixing must be strong enough to withstand ballast unloading during track maintenance.
For safety clearance:

• The height of the arrangement should not exceed 75 mm above the sleeper surface,

• and the width should not exceed 380 mm along the sleeper.

Location Considerations

When deciding installation points, some precautions are followed:

• RFID tags should not be placed at turnouts,

• or at level crossings, where ballast accumulation occurs,

• or in water-logged areas, to avoid damage.

In block sections, tag placement also considers ease of maintenance and minimizing the risk of vandalism. This ensures long-term reliability.

Summary

To summarize:

• RFID tags and readers are the core of the KAVACH system.

• KAVACH uses passive, read/write tags operating in the UHF band.

• Correct fixing and thoughtful location planning are critical for reliable functioning.

• With these measures, KAVACH ensures safe train operation even at high speeds of up to 250 km/h.

Thus, RFID tags serve as the backbone of safe train control and collision avoidance.

Classification of Tags in Stationary Kavach System

Good morning everyone!
Welcome to this session on Classification of Tags in the Stationary Kavach System, designed especially for Signal and Telecommunication Engineers.
In today’s session, we’ll understand how different RFID tags are used in the Kavach system — their functions, locations, and importance in ensuring safe and reliable train operations.

Learning Objectives

By the end of this session, you should be able to:

1. Identify the different types of tags used in the Stationary Kavach system.

2. Understand where and why each tag is installed.

3. Learn how accurate placement affects train detection and system performance.

4. Relate the function of tags to the overall Kavach safety mechanism.

So, let’s begin with an overview of how these tags are classified.

Overview of Tag Classification

In the Stationary Kavach System, several types of RFID tags are installed along the track.
Each serves a specific role in location correction, communication, and train protection.

They include:

• Signal Foot Tag

• Signal Approach Tag

• Normal Tag

• TIN Discrimination Tag

• LC Gate Tag

• Kavach Exit Tag

• Adjustment/Junction Tag

• Adjacent Line Tag

• Tunnel Tag (for future use)

These tags work together to continuously update the train’s position and ensure correct signaling logic.

Signal Foot Tag

Now, let’s start with the Signal Foot Tag.
This tag is provided at the foot of every signal post, except shunt signals.
It serves as a reference point for the signal’s exact location.

You’ll also find these tags at permanent End of Authority (EoA) locations like Stop Boards and Block Section Limit Boards (BSLB).

The foot tag helps the Kavach system identify the precise location of signals so that braking and authority limits can be applied correctly.
Without this tag, the system wouldn’t know the exact stopping point associated with a signal.

Signal Approach Tag (Normal Tag as Approach Tag)

Next, we have the Signal Approach Tag.
This tag is installed before the approach of every signal and plays a key role in correcting odometry error — that’s the distance error accumulated by the loco system due to wheel slip or measurement drift.

Placement guidelines:

• The tag should be installed 150 to 250 meters before the signal foot tag — ideally at 200 meters.

• The distance must be an exact multiple of one meter — accuracy here is critical.

• For Advanced Starter or Intermediate Starter signals, the minimum distance can be 120 meters.

Other tag types like LC tags or normal tags can sometimes serve as approach tags too.
This tag ensures the loco knows exactly how far it is from the next signal — crucial for braking calculations.

Normal Tag

The Normal Tag is used both in station and block sections.
Its job is to help maintain odometry accuracy and support loco–station communication.

The distance between two normal tags should not exceed 1000 meters.
There’s also a special kind called the Border RFID Tag, which marks the limit up to which the locomotive can communicate with the previous station’s SKavach unit.
Once it crosses this tag, it starts communicating with the next station’s SKavach.

This ensures a smooth transition between zones and uninterrupted data exchange for train protection.

TIN Discrimination Tag

Now let’s move to TIN Discrimination Tags.
TIN stands for Track Identification Number.
These tags indicate that the train is moving to a different track section — for example, when a train passes through a turnout or junction where two lines merge or overlap.

They help the system distinguish between tracks and prevent incorrect location mapping.
So, TIN tags are mainly found at turnouts, crossovers, or points with overlaps.

This allows the onboard system to immediately recognize that it has entered a new track, maintaining accurate positional awareness.

LC Gate Tag

The LC Gate Tag is primarily used for automatic whistling when approaching a Level Crossing gate.
This ensures safety at level crossings even if the driver forgets to whistle.

These tags are placed on both sides of the LC gate.
They are positioned so that the auto-whistling starts at least 600 meters before the gate — typically near the W/L board.

This provides sufficient warning to road users about an approaching train and enhances safety at unmanned or manned LC gates.

Kavach Exit Tag

Next, we have the Kavach Exit Tag, which marks the boundary of the Kavach-controlled territory.

It is installed wherever trains are expected to:

• Move outside Kavach coverage, or

• Remain stationary for long durations, like at sidings.

At least two exit tags are placed, separated by a minimum of 10 meters.
When the locomotive crosses the exit tag, the onboard system recognizes that it has exited the protected zone and stops receiving authority updates from the stationary Kavach unit.

Adjustment/Junction Tag

The Adjustment or Junction Tag is used for correction of absolute location.
Even though odometry and other tags maintain accuracy, small positional errors may still occur over long distances.
This tag helps reset or realign the position precisely.

You’ll find these tags in block sections and at junction stations.
They are especially useful in complex track layouts where exact positioning is critical for route determination and train protection.

Adjacent Line Tag

The Adjacent Line Tag, identified by the letter ‘L’, contains information about adjacent lines — up to five lines can be encoded.

This tag plays a vital role in side collision detection.
It allows the system to identify nearby tracks and determine whether any other train is dangerously close on a parallel line.

This improves safety in multi-line corridors, especially where trains run in close proximity.

Tunnel Tag (Future Use)

The Tunnel Tag is reserved for future applications.
It will likely be used for detecting tunnel entry and exit points, enabling automatic adjustments to radio communication or system alerts when trains move through long tunnels.

Although not currently active in most deployments, it’s part of the planned expansion for the Kavach system.

Summary

Let’s summarize what we’ve learned today:

• Each tag type has a specific operational purpose — from signal recognition to odometry correction.

• Accurate placement and exact distance measurement are crucial for system reliability.

• Tags ensure the loco always knows where it is, which signal it’s approaching, and whether it’s in a safe zone or not.

In short, these tags are the foundation of the Kavach’s safety and location system.

Medha Stationary KAVACH Architecture

Introduction to Medha Stationary KAVACH

Today we’ll discuss one of the most vital components of the Train Collision Avoidance System — the Medha Stationary KAVACH Architecture.

The KAVACH system is designed to prevent train collisions by continuously exchanging vital safety information between trains and the signaling system.

It mainly consists of two parts:

• The Loco KAVACH Unit, which is installed in the locomotive, and

• The Stationary KAVACH Unit, which is installed at the station, interlocked gate, or IBS location.

Our focus today will be on the Stationary KAVACH — its sub-systems, internal modules, and their working principles.

Station KAVACH Unit Overview

The Station KAVACH Unit is housed inside a standard equipment bin.
Within this unit, several circuit boards and modules work together to process data, communicate with the locomotive, and maintain continuous safe train operation.

This unit performs four key functions:

1. Processing vital information from the interlocking system.

2. Communicating with the loco KAVACH units.

3. Logging important events and faults.

4. Supplying stable power to all internal modules.

In simple terms, you can think of this as the brain of the station-side safety system.

Station KAVACH Unit Modules

The Station KAVACH unit is made up of six major modules.
They are:

• Vital Computer Card

• Vital Input Card

• Communication Interface Card

• Event Logger Card

• Modem Card

• Power Supply Card

Each of these has a specific role — some perform logic and safety calculations, others handle communication or power management.
We’ll now look at each module in more detail.

List of PCBs in Station KAVACH Unit

This table lists all the Printed Circuit Boards, or PCBs, used inside the Station KAVACH bin.
Each has a unique part number and specific function.

For example:

• The Vital Computer Card, part number M110VCC-01, is the processing unit.

• The Vital Input Card, M110VIP-01, is yard specific because it depends on the number of signals, points, and track circuits.

• The Modem Card, M110MDM-01, is used for communication with IB or LC huts.

Note that the Power Supply and Backplane cards differ between top and bottom modules, depending on yard configuration.

Vital Computer Card

The Vital Computer Card is the most important module — it’s the brain of the Station KAVACH.
It is designed with dual electronic structure, often referred to as 2-out-of-2 architecture.

This means it has two independent processors — VP1 and VP2.
Both processors run the same software and perform the same calculations.
They continuously cross-check each other’s results through inter-processor communication.
Only when both outputs match, the system accepts it as valid.

This design ensures fail-safety — if any one processor fails or produces a wrong result, the system immediately goes to a safe state.

The Vital Computer Card receives input information like signal aspects, point positions, track circuit occupancy, and block line status from the Vital Input Card.
Using this data, it determines the signal aspects and calculates the movement authority.
Finally, it sends this information as a signal packet to the Loco KAVACH unit.

Vital Input Card

The Vital Input Card acts as the interface between the interlocking system and the Station KAVACH.
It reads the outputs of the interlocking through potential-free contacts, which include:

• Signal aspects

• Point positions

• Berthing track circuit status

• Block instrument line closed condition

To ensure reliability, each CPU in the KAVACH has its own set of input cards.
This avoids any common mode failures — for example, a short circuit or wiring issue on one set won’t affect the other.

If a mismatch occurs between the two sets of inputs, the system identifies the fault and automatically moves to safe mode.

Communication Interface Card

The Communication Interface Card, also called the Peripheral Interface Card, enables communication between the Vital Computer and other subsystems.
It handles serial communication with:

• Radio modules

• GPS modules

• Electronic Interlocking (EI)

• SOIP communication system

This card ensures that the Station KAVACH can exchange information with field devices and central systems in real-time.
Essentially, it’s the communication hub that keeps all modules connected.

Event Logger Card

The Event Logger Card functions as a data recorder or the ‘black box’ of the Station KAVACH system.
It communicates with the Vital Computer to receive system events and fault information.

All system activities — such as signal changes, communication logs, and fault occurrences — are recorded here.
These logs can then be transmitted to the Centralized Management System using GSM or Ethernet connectivity.

This feature is very useful for fault diagnostics, post-incident analysis, and system maintenance.

Modem Card

The Modem Card provides communication between the Station KAVACH and field units like Intermediate Block Stations, Level Crossing Gates, or Huts.

It uses a quad cable for full duplex data communication — meaning data can flow in both directions simultaneously using a single pair.
The modem card modulates and transmits data from the Vital Computer to the field VIPs, and demodulates the received data before sending it back to the Station KAVACH computer.

In short, it ensures continuous and reliable data exchange between the station and its remote KAVACH units.

Power Supply Card

The Power Supply Card provides the required operating voltages for all modules.
It receives a +24V DC input and can operate within a range of +30% to -20%.

This module includes built-in protections such as:

• Under and over-voltage protection

• Short circuit protection

• Overload protection

So even if there are fluctuations or faults in the power supply, the system remains stable and safe.
Reliable power is absolutely essential in a fail-safe signaling system like KAVACH.

Summary

To summarize, the Medha Stationary KAVACH is a powerful and intelligent safety system that integrates seamlessly with the station interlocking.

Its dual-redundant vital computer ensures fail-safe decision making.
The input, communication, and event logging modules maintain constant situational awareness.
And the modem and power cards ensure stable field communication and power.

Together, they form the backbone of the Train Collision Avoidance System, significantly enhancing rail safety and reliability.

Station Kavach System Controls and Indications

Good morning everyone. Today we will focus on a very important part of the Stationary Kavach System—its controls and indications. Understanding the LED indications, connectors, and diagnostic interfaces on each card is essential for installation, configuration, maintenance, and troubleshooting. This session covers the key cards used in MEDHA make Station Kavach: the Vital Computer Card, Vital Input Card, Communication Interface Card, Event Logger Card, Modem Card, and Power Supply Card.

System Controls and Indications – Overview

Before configuring or performing maintenance on the Stationary Kavach system, it is important to understand the front-panel controls and LED indications on each PCB. These indicators help the technician quickly assess the operational state of each subsystem. The LEDs tell us about power status, communication status, cyclic activity, and faults. Accurate interpretation of these indicators ensures timely detection of failures and fast recovery.

Vital Computer Card (M110VCC-01)

This slide describes the Vital Computer Card, one of the most critical components in the Station Kavach unit.

• The Power LED indicates the presence of 3.3V supply.

• CYC LED toggles every cycle—the blinking confirms that the CPU is active and looping normally.

• IPC LED shows the status of inter-processor communication.

• The card communicates with multiple subsystems such as GPS-1, GPS-2, Event Logger, VIP cards, OCIP, and Radio Cards, each represented with its own LED.

• If any link fails, the respective LED either turns off or becomes constant.

• The 7-segment display shows fault codes, which are critical for troubleshooting. These codes help identify precise module-level faults.

Vital Input Card (M110VIP-01)

The Vital Input Card receives and processes 24 vital inputs from the station interlocking.

• The POWER LED confirms the 3.3V supply.

• CYC LED indicates that the VIP card is functioning in sync with the vital computer.

• The COM LED confirms communication with the Vital Computer.

• LEDs marked IP1 to IP24 represent the pickup or drop status of each input. These help technicians verify real-time field information such as track circuit occupancy, signal states, route status, and point detection.

Communication Interface Card (M110CIF-01)

This card manages the communication between the Station Kavach system and external components such as GPS antennas and radio devices.

• GPS-A and GPS-B connectors are used for GPS receiver antennas.

• The OFC connectors are crucial, as they carry diagnostic and COMP communication between Radio-1 and Radio-2.

• LEDs such as VHMPWR, INTPWR, and V STS indicate the power and health of the voltage monitoring system and vital computer.
  If any of these indicators show abnormal status, it may lead to communication failure, degraded mode, or loss of radio connectivity.

Event Logger Card (M110EVL-01)

The Event Logger Card is responsible for recording all system events, logs, and diagnostics.

• It has power and cyclic LEDs indicating basic functionality.

• GSM-1 and GSM-2 antennas provide mobile connectivity for transferring logs.

• ETH LED confirms Ethernet communication with adjacent stations via E1 interface.

• VCA and VCB COMP LEDs show communication with Vital Computer A and B.

• USB ports are used for pendrive data extraction and laptop-based diagnostics.
  This card is essential for post-incident analysis and system audits.

Modem Card (M110SMDM-01)

The Modem Card forms the communication backbone between the VCC, VIPs, and external communication channels.

• The LEDs indicate link status, master/slave configuration, and data transmission or reception.

• If the ERR LED glows, it indicates communication failure or modem malfunction.

• The RS485 connector is the key interface to VCC or VIP cards.
  Understanding the behavior of TD and RD LEDs is important—as they must blink during active communication.

Power Supply Card (M162STPS-01)

The final card in this module is the Power Supply Card.

• It receives 24V input and distributes regulated outputs like 4.5V, 6.2V, and isolated 5V.

• Each voltage output has a corresponding LED that clearly indicates whether the supply is healthy.

• If the ERR LED lights up, it indicates a power supply fault, which could impact multiple subsystems.
  A failure in this card may bring down the entire Station Kavach system, so monitoring these LEDs is extremely important.

Closing Statement

In summary, each card in the Stationary Kavach system is equipped with specific indicators and connectors that provide real-time operational status. A proper understanding of these indications helps technicians quickly diagnose issues and ensure safe, reliable functioning of Kavach. In the next session, we will explore troubleshooting procedures and common fault scenarios.

MEDHA STATIONARY KAVACH System Start Up

Good morning. Today we will cover the start-up procedure for the MEDHA Stationary KAVACH system.Here I’ll walk you through the pre-power checks, power-on steps, the LED and display indications on each subsystem, the Remote Interface Unit modules, a start-up checklist, common troubleshooting, and safety reminders. By the end of this session you should be able to power the system safely and verify that all internal functions are healthy.

Agenda

Here’s our agenda for the lecture. First I’ll give a brief overview of why the start-up procedure matters. Then we’ll go through the initial pre-power checks you must perform. After that we’ll do the actual system power-on steps and cover the expected indications for each subsystem card. We’ll look at RIU modules, present a concise start-up checklist, discuss common troubleshooting actions, and finish with safety guidance.

Overview of Start-Up Process

The purpose of this start-up process is to verify that the installed KAVACH unit is electrically and functionally sound before commissioning it into the field. A controlled and repeatable power-up ensures power rails, communications, and CPUs are healthy and avoids damage to electronics or field interfaces. Our expected outcome is a confirmed “system healthy” state, with all required links and inputs reporting correctly.

Initial Pre-Power Checks

Before applying mains, perform these physical and wiring checks:

• • Verify there are no loose wires hanging from any PCB. Loose wiring is the most common cause of intermittent failures.

  • Ensure the facia LEDs and displays on all PCBs are in the OFF state prior to power; this indicates no residual power or incorrect wiring.

  • Check that no PCB is projecting outside the chassis and that all fixing screws are tightened to secure each board.

  • Confirm the field power cable is correctly connected to the Power Supply card and any required relay contacts are properly wired.

  • Make sure all relays are seated in their respective slots.

  • Verify the User Interface unit is connected properly so you can observe status and readouts during start-up.

  • Finally, ensure all communication and power cables are properly terminated and routed to avoid shorts or noise coupling.

• Take time on these checks — they prevent most start-up problems.

System Power-On Steps

Once the initial checks are complete, proceed to apply power:

• • Switch ON the 110V mains in the IPS room to power the Station KAVACH unit.

  • After mains are applied, observe the LED behavior on each subsystem in sequence.

  • Do not move to field activation until the central indications show the system is healthy.

  • If anything deviates from expected indications, remove mains and troubleshoot using the checklist we’ll cover shortly.

Station Vital Computer Card (M110VCC-01)

• On the Vital Computer card, watch for these indications:

  • LED(POWER) should be ON (Yellow), confirming the 3.3V rail is present.

  • LED(CYC) will blink Green to show the CPU is in cyclic activity.

  • Communication LEDs such as IPC, GPS-1, GPS-2, EVL, VIP, OCIP, and RAD should blink Green, indicating healthy communications with the adjacent CPU, GPS modules, Event Logger, Vital Input cards, OCIP, and Radio respectively.

  • The 7-segment display should read “00” — that is the system healthy code. If any comm LED remains dark or the 7-seg does not read 00, do not proceed to field operations.

• These indicators are the primary health snapshot for the whole station.

Vital Input Card (M110VIP-01)

• The Vital Input card also shows power and activity:

  • LED(POWER) ON (Yellow) indicates the 3.3V supply is okay.

  • LED(CYC) blinking Green shows the VIP CPU is cycling.

  • LED(COM) blinking Green confirms communication between VIP and VCC.

  • LEDs labeled IP-1 to IP-24 show the state of each field input. A Yellow ON indicates a pick-up condition; OFF indicates a drop. Use these to verify expected field relay statuses after wiring and during test activations.

• Check that inputs correspond to your field test conditions.

Event Logger Card (M110EVL-01)

• For the Event Logger card:

  • LED(POWER) ON (Yellow) confirms 3.3V.

  • LED(CYC) blinking Green indicates the CPU is active.

  • LED(VCA COM) and LED(VCB COM) blinking Green show communication with the two VCs (VCA, VCB).

• Event logger communications are important for diagnostics and post-event analysis, so ensure these LEDs blink as expected.

Modem Card (M110SMDM-01)

• The Modem card shows link and configuration status:

  • LED(PWR) ON (Yellow) confirms the modem power rails.

  • LED(M1-L) and LED(M2-L) ON (Green) indicate Modem 1 and Modem 2 links are established.

  • The master/slave roles are shown by M and S LEDs. One modem should show M ON and the other S ON to reflect the configured master and slave setup.

  • LED(TD) blinking Green indicates data transmission; LED(RD) blinking Green indicates reception.

  • LED(ERR) should be OFF — that signifies no modem error.

• Verify modem links and roles align with your network design before enabling traffic.

Station Power Supply Card (M110STPS-01)

• On the Station Power Supply card:

  • LED(POWER) ON (Yellow) confirms the 3.3V logic rail.

  • LED(4.5V), LED(6.2V), and LED(ISO 5V) should be ON (Green), confirming the local voltages are within expected range.

  • LED(ERR) should be OFF. If any voltage LED is off, investigate PS card connections, input mains, fuses, and the 24V source as applicable.

• Proper PSU operation is foundational — never ignore a missing voltage LED.

Remote Interface Unit Modules

• The RIU comprises multiple modules; know their roles:

  • Station Bottom Bin Power Supply (M110SBPS) generates the required electronics voltages from the 24V supply.

  • Vital Input Card (M110VIP) interfaces field input relays to the station electronics.

  • Bottom Back Plane (M110SBBP) provides the communication pathways between boards.

  • RS485-OFC Bidirectional Converter (M110OFBS) supports RS485 to OFC conversion enabling RIU ring topology for resilient communications.

  • Battery Charger (M110BC) converts mains voltage ranging from 100V–260V AC to 24V DC to power RIU modules.

  • Field Interface Card (M110FIC) bridges field input signals to the VIP card via the FRC cable.

• Understanding each module helps isolate faults during RIU-level troubleshooting.

Start-Up Checklist (Concise)

• Follow this condensed checklist when powering up:

  1. Complete the initial pre-power checks from slide 4.

  2. Switch ON mains at the IPS room.

  3. Confirm POWER LEDs on PS and VCC cards are ON.

  4. Check CPU cyclic and communication LEDs on VCC, VIP and EVL are blinking.

  5. Verify the VCC 7-seg display reads 00 before enabling any field outputs.

  6. Confirm modem link LEDs and master/slave configuration are correct.

  7. Only after all checks pass, proceed to field activation or commissioning tests.

Common Troubleshooting Steps

• If you see a power LED OFF: confirm mains at the IPS, check PS card connectors, fuses, and the 24V input to the RIU.

• If communication LEDs are not blinking: reseat the backplane, verify ribbon and communication cables, and check termination resistors and RS485 wiring.

• If the modem link is missing: inspect antennas or physical lines, confirm modem configurations (master/slave), and test link LEDs.

• If the 7-seg display doesn’t show 00: check the VCC cyclic LED; log current LED states, power-cycle after securing connectors, and escalate to engineering if the CPU fails to initialize.

• In all cases, document LED states and any log entries before rework or replacement so faults can be traced accurately.

Safety and Handling Reminders

• Always isolate mains before doing any wiring or mechanical work.

• Secure PCBs and cables to prevent vibrational loosening during operation.

• Handle PCBs only by the edges and avoid contact with components or connector pins.

• Keep wiring diagrams, block diagrams, and start-up checklists at hand during the procedure.

• If you encounter unknown behavior, stop, isolate power, and consult the technical manual or engineering support.

Demo Plan and Live Walkthrough

• For the demo we will:

  • Perform the physical inspection checklist live so you can see what to look for.

  • Apply mains and observe LED transitions on VCC, VIP, EVL, modem, and PS cards.

  • Show how to read modem master/slave and link status.

  • Demonstrate reading VIP inputs IP-1 to IP-24 by simulating pick-ups and drops so you can correlate field wiring to VIP LEDs.

Maintenance of Kavach System (Medha)

Today, we are going to discuss Maintenance of the Medha Station Kavach System.
This lecture will help you understand how routine maintenance is performed, what tools and spares are required, and the correct procedures for handling cards, software, and event data.

Introduction

The Kavach system is a critical safety device, and its maintenance is essential to ensure reliability.
Scheduled maintenance helps detect early symptoms of equipment degradation before they lead to failures.

Personnel working on Kavach must be thoroughly familiar with the proper operating procedures, testing methods, and repair guidelines.
This lecture covers all essential procedures needed for maintaining the Medha Station Kavach equipment.

Objectives

The key objectives of today’s session are:

• To understand the routine maintenance practices of the Medha Station Kavach system.

• To become familiar with the recommended tools and spare parts.

• To learn the correct procedures for replacing cards and updating software.

• To understand how to handle electrostatic protection.

• And finally, to learn how to download system data using the Event Logger.

Tool Kit Requirements

To carry out the maintenance tasks, a specific set of tools is required.
The tool kit includes a digital multimeter, ring spanner, open-end spanner, socket spanner with handle, and two types of screwdrivers—No. 902 and No. 935.
These tools are essential for safely and accurately handling hardware components during maintenance.

Recommended Spares

For reliability, the system requires that 10% of spare cards be maintained.
This ensures that defective cards can be replaced quickly without delaying operations.

Holding Spare Parts

All repairs to components and electronic cards must be done only by the manufacturer.
Customers or maintenance staff should not attempt any internal repairs.

Spare cards must be tested once every year, following test methods defined by the manufacturer.

Additionally, all spare components must be examined every five years.
This long-term check ensures that spares remain usable and do not degrade while in storage.

Changing the Cards – Guidelines

When replacing cards, we must follow strict safety procedures:

• First, only tested cards should be used for service.

• If any card is found defective, it must be replaced immediately.

• Very important—never replace cards while the system is powered ON.
  This helps prevent electrical damage and ensures personnel safety.

• All cards must be stored using proper electrostatic discharge precautions.

• Before inserting a replacement card, check that:

  • The software version is approved,

  • The jumper settings match,

  • And the card is inserted into the correct slot.

• When removing cards, pack them carefully to avoid mechanical or ESD damage.

Changing the Software – Procedure

When software needs to be updated, follow this sequence:

1. First, switch OFF the system power.

2. Remove the cards that require programming.

3. Program the cards using the method given in the user manual.

4. Finally, reinstall the cards into their correct slots.

Following this process ensures that software updates are done safely and accurately.

Periodic Maintenance Activities

Periodic maintenance is very important for ensuring smooth operation.
During routine checks, the service engineer must:

• Download the events and fault logs and store them with date and time stamp.

• Inspect wiring to ensure there are no loose contacts.

• Check all nuts and bolts in the cabin for tightness.

• Monitor the input power supply at the terminal board and confirm that it is within the specified limits.

These steps help maintain system stability and prevent unexpected failures.

Electrostatic Protection

Since electronic cards are sensitive to electrostatic discharge, personnel must follow ESD protection measures:

• Always stand on an approved conductive floor mat when handling printed circuit boards.

• Wear a wrist strap grounding device with a 1 mega-ohm resistor.

• Check the continuity of the wrist strap regularly. It must read between 500 kilo-ohms and 10 mega-ohms.

• Handle all PCBs only by the edges—never touch the components directly.

• Immediately place any removed board into a conductive-shielded bag, and wrap it in conductive foam for transportation.

Strict adherence to these guidelines prevents costly damage to electronic components.

Event Logger – Overview

The Event Logger plays a vital role in system diagnostics.
It receives information from the system’s vital computer cards—this includes software version details, checksums, faults, and events.

The Event Logger stores all this data in a 128 MB external flash, which can hold over one lakh events.
When the memory becomes full, it overwrites older events in a FIFO manner.

Data Downloading – Modes

Event data can be downloaded through the USB interface provided on the Event Logger.

There are two modes of operation:

1. Online Mode – The logger is part of the system and communicates with the CPUs.

2. Offline Mode – The logger works independently, like a standalone module.

During regular monthly maintenance, data must be downloaded using the application tool and saved for record-keeping and analysis.

Summary

To summarize, maintaining the Kavach system involves:

• Performing periodic inspections

• Following strict ESD safety guidelines

• Using only tested and approved spare parts

• Carefully handling card replacements and software updates

• Downloading and preserving system logs every month

Proper maintenance ensures the reliability and safety of the entire Kavach system.

HBL STATION KAVACH ARCHITECTURE

HBL Station Kavach Architecture

Today we will discuss the architecture of the HBL Station KAVACH system, which is a crucial part of the Automatic Train Protection system deployed in Indian Railways.
Stationary KAVACH units come in three forms: Station KAVACH, IBS KAVACH, and LC Gate KAVACH.
All of them are microcontroller-based and communicate continuously with the Loco KAVACH to ensure safe train movement.

Role of Stationary KAVACH

The Stationary KAVACH performs multiple safety-critical tasks.
It receives real-time position, speed, and direction information from the Loco KAVACH using radio communication.
It also monitors the field inputs—signal aspects, track circuits, points—and calculates the valid movement authority for each locomotive approaching the station.
This movement authority is transmitted back to the loco so that the onboard KAVACH can supervise the train.
In case of an emergency or unsafe condition, the Stationary KAVACH sends an SOS command to initiate automatic braking and prevent collisions.

Station KAVACH Components

The Station KAVACH unit is generally installed inside the station relay room.
It consists of several interconnected sub-systems:
KAVACH subsystem, FIU subsystem, power subsystem, GPS/GNSS receiver, GSM unit, SM-OCIP, radio modems, radio antennae, and the RFID tag system installed on the track.
All these components operate together to create a complete ATP environment.

Field Inputs & Interfaces

All field inputs—signals, points, track circuits, and berthing tracks—are wired into the Field Interface Unit or FIU.
Radio antennas are mounted on a 30-meter tower and linked to radio modems for communication with locomotives.
GPS/GNSS receivers and SM-OCIP modules remain connected to the main KAVACH subsystem.
RFID tags fixed on sleepers help the system identify exact train location.
All modules are housed in 19-inch sub-racks to maintain structured installation.

Subsystem Connectivity

The Stationary KAVACH contains multiple sub-systems interconnected through wire-harnesses.
Module-level connections use automotive-grade connectors, while sub-systems use MIL-grade connectors for robust and reliable interfacing.
MIL connectors are also used for connecting external peripherals, ensuring the system remains safe and interference-free even in harsh outdoor railway environments.

KAVACH Subsystem Modules

The KAVACH subsystem is the core processor of the system.
It includes:
• Peripheral Processing Module
• Vital Computer Module
• Voter Module
• Data Logging Module
• GSM Module

The Vital Computer ensures safety logic, the Voter module validates decisions, and the Data Logger captures all events for analysis and troubleshooting.

FIU Subsystem

The FIU, or Field Interface Unit, is responsible for collecting all field inputs.
It consists of the main FIU module and a termination module where wiring from signals, track circuits, and points is landed.
The FIU converts these field inputs into digital data that the KAVACH subsystem can process.

Ethernet Communication

The Stationary KAVACH uses an Ethernet interface through its Integrated Data Logger card.
This interface allows communication with the Network Management System server and neighbouring IBS or HUT KAVACH units.
It also allows engineers to download error logs directly to a laptop or PC for maintenance and issue analysis.

Power Supply Module

The system requires stable 24V DC and 5V DC supplies.
The Digital Power Supply modules generate these voltages from the available 110V DC input.
Two DPS units provide redundancy.
Each 24V supply line is protected with fuses, and power monitoring is performed continuously to protect against overload conditions.

Power Channels

The 5V channels are divided into two types:
• 5V_CAN1 and 5V_CAN2 – powering CAN bus communication channels.
• 5V_ISO1 and 5V_ISO2 – powering RS232, RS485 and GPIO interfaces.
All 24V and 5V supplies are electrically isolated, ensuring no noise or fault propagates between modules.

FIU Termination Card

Now let us begin with the FIU Termination Card, which plays a key role in handling all field inputs coming from the station yard.
The FIU supports a total of 1024 field inputs, and to manage these, we use six FSC sub-racks.
Five of these sub-racks each carry 12 FSC cards, contributing 960 inputs.
The sixth sub-rack carries four FSC cards, providing the remaining 64 inputs.
This sixth rack also houses the FIU Interface Card, or FIC, which communicates with all FSC cards over the CAN Bus.
All scanned field input states are sent to the FIC, making it the central collection point for field information.

FIU Scanner Card (Overview)

The FIU Scanner Card is responsible for reading field inputs and reporting them to the system.
The FIU sub-rack supports up to 4096 field inputs, divided into four groups of 1024 each.
Each 1024-input group is divided further into 32 subgroups, and each subgroup supports 32 field inputs.
To read each subgroup, we use a dedicated FIU Scanner module.
This structured hierarchy gives precise control and scalability.

FIU Scanner Card (Redundancy & Function)

To increase system availability, every set of 32 field inputs is scanned by two FIU Scanner modules.
If one module fails, the second automatically ensures continuity.
Each scanner module sends data to the Vital Computer using a dual-isolated CAN Bus, ensuring safety and noise-free communication.
The total number of FIU scanner modules required depends on how many field inputs exist at a particular station.

Peripheral Processing Card (PPC)

The Peripheral Processing Card, or PPC, acts as the main interface for external peripherals like GPS/GNSS, radio modems, SM-OCIP, and the yard viewer.
The GPS system provides a 1-second marker that synchronizes all system time functions.
The PPC handles RF communication with locomotives through radio modems.
It also passes the collected data to the Vital Computer over the CAN Bus.
There are always two PPC modules—one active and one hot-standby—to ensure redundancy.

PPC LED Indicators

Each PPC card has several LED indications for health and status monitoring.
The PWR LED indicates availability of 24V power supply.
Radio-related LEDs—RDAC and RDRT—light up when the radio is active and when packets are received or transmitted.
Multiple controller health LEDs such as HLT1 to HLT4 indicate the status of different microcontrollers inside the PPC.
Other indicators like SPD show the health of the speedometer circuit, and RGS confirms the GPS status.
These indicators help technicians quickly diagnose issues.

Vital Computer Card (VC)

The Vital Computer is the core safety processor of the KAVACH system.
It receives input data from the PPC and processes it to take safety-related decisions.
The design uses three Vital Computers working in parallel to implement the ‘2-out-of-3’ or 2oo3 architecture.
This ensures that any incorrect decision by one computer will be overruled by the other two.
The output of these computers is sent to the Voter module.

Voter Card

The Voter Card receives the processed decisions from all three Vital Computers.
Using the 2oo3 voting logic, it decides the final safe output that the system should follow.
There are two Voter modules operating in hot-standby mode to ensure reliability.
Once the final decision is made, it is sent through the CAN Bus to the relevant destination modules.

Voter Card LED Indicators

The Voter Card includes a series of LEDs to indicate system condition.
The PWR LED confirms 24V supply.
VTS shows the voter status while SYS shows overall system status.
CMS and CNS represent communication health.
BMS indicates bus-master status, and TTM shows the time-trigger status.
HLT1 and HLT2 reflect the health of the core and bridge microcontrollers.
All these LEDs help technicians identify faults quickly.

Integrated Data Logger Card

The Data Logger Card plays a vital role in diagnostics and communication.
It logs radio packets, system health information, error events, and NMS data received over the CAN Bus.
It supports multiple memory interfaces such as SD/MMC, USB, EEPROM, and data flash for storing logs.
Using its Ethernet interface, it connects the station KAVACH unit with IB huts and nearby stations.
Logs can also be downloaded through the USB interface.
Additionally, it updates real-time yard status on the Yard Viewer.

GSM Card

The GSM module ensures long-distance communication with NMS and KMS.
It supports two GSM service providers working simultaneously, improving availability.
Two GSM modems are used for redundancy.
Through this module, events and faults are logged into NMS, and security keys are fetched from the KMS.
In emergency conditions, the GSM card can send SMS alerts to concerned authorities.
This makes it an essential communication and safety component.

Conclusion

With this, we have covered the FIU, PPC, Vital Computer, Voter, Data Logger, and GSM subsystems of the Station KAVACH.

Each of these modules contributes to high reliability, redundancy, and safety in the overall Train Collision Avoidance System.

Understanding the function and diagnostics of each module is essential for effective

Maintenance of KAVACH System – HBL Make

Today we are going to learn about the Maintenance of Stationary KAVACH System of HBL make.
This session will help S&T Teams understand the structure of the KAVACH units, its sub-components, and the maintenance procedures required to ensure reliable train protection.

Introduction

KAVACH is the train protection system developed for Indian Railways.
In station sections, we use the Stationary KAVACH unit.
This unit is installed in the Relay Room and provides real-time information exchange with trains and adjacent stations through Radio and E1 network.
It also communicates with SM-OCIP and Yard Viewer to support station operations.

Sub-rack Details

A standard Stationary KAVACH unit consists of a 19-inch KAVACH sub-rack.
It accommodates up to 12 electronic cards.
Below this rack, we have the Field Interface Unit – FIU.
FIU collects inputs from interlocking relays and sends their status continuously to the KAVACH system.
This ensures real-time monitoring of field conditions.

KAVACH Sub-System Cards

These are vital safety-related cards:

• The PPC card handles peripheral processing

• The Vital Computer card runs the core safety logic

• The Voter card performs decision voting to ensure fail-safety

• The Integrated Data Logger records all operational logs

• The Dual GSM card supports GSM communication and fallback networking
  Each card has a specific role in maintaining safety integrity of the system.

Additional Station Cards

Other support modules include:

• FIU Scanner: scans field inputs and sends relay states

• Ethernet switch: connects KAVACH components via LAN

• RS-232 extender: helps in serial communication extension

• LAN extender: extends network for connectivity with external systems
  These help the main KAVACH modules interface smoothly with field elements.

Connector Information

All cards are connected using robust pin connectors.
Most cards have one 28-pin and two 40-pin connectors.
Only the IDL and GSM cards have one 28-pin and one 40-pin connector.
Proper seating and locking of connectors must be ensured during maintenance to avoid faults.

IB-KAVACH Note

In IB sections, only one rack is provided.
The number of FIU Scanner cards is less since the field inputs are limited.
But otherwise, the functionality remains the same.

Installation Locations

KAVACH installation is distributed across multiple station locations:

• IPS Room provides 110V DC power

• RRI Room houses the main stationary unit

• Location Box near Radio Tower contains Radio Modems

• OFC Hut houses E1 modem for RAILTEL connectivity

• SM Room contains the SM-OCIP interface

• In IB sections, KAVACH is installed in IB-Hut
  Technicians must be familiar with all these locations when performing maintenance.

Sub-systems for Maintenance

The Stationary KAVACH system consists of five main sub-systems we maintain regularly:

1. Power Input System

2. Station Electronic Unit

3. Modem Interface

4. Radio Interface

5. SM-OCIP
   Maintenance checks must cover all these to ensure full working condition.

Power Input Specifications

KAVACH operates on 110 Volts DC, supplied from the station IPS system.
There are two separate power feeds:

• One for KAVACH station unit

• One for Radio system in location box
  Each feed has a dedicated fuse for protection.

Power Supply Maintenance

For checking power supply, we use a Digital Multimeter set to the 110V DC range.
We check voltage at:

• Input terminals

• Across the fuses

• Output terminals
  If voltage is missing or abnormal, fuse continuity must be checked.
  Also, during quarterly checks, we must measure earth leakage to ensure system safety.

MCB Arrangement

The MCBs for both KAVACH and Radio power supply are mounted on the KAVACH Panel.
These should always be in the ON position during system operation.

MCB Maintenance Checks

During maintenance, verify:

• MCB condition and ON/OFF state

• 110V DC availability at all test points
  If voltage is missing, check wiring and replace fuses if blown.
  Correct power availability is the first requirement for system functioning.

Safety Precautions

Safety is extremely important when working with 110V DC circuits.
Before performing maintenance:

• Switch OFF the MCB

• Remove the respective fuses
  This prevents short circuits and protects the technician as well as equipment.
  Always follow standard safety and ESD practices.

Summary

To summarize today’s lecture:

• Stationary KAVACH consists of multiple sub-racks and safety cards

• FIU continuously monitors relay state

• Proper 110V DC power supply is essential

• Regular inspection of fuses, wiring, connectors, and earth leakage is mandatory
  Our goal is to keep the system fully reliable for safe train operations.

Station Unit Maintenance (HBL Make)

________________________________________

Today we will be discussing the Station Unit of the Stationary KAVACH System – specifically its components and the maintenance procedures involved.

This is part 2 of the KAVACH Maintenance Training Module for S&T Team.

________________________________________Station Unit Overview

The Station Unit comprises three main parts:

The KAVACH sub-system

The FIU sub-rack

The Power supply unit

All three work together to perform vital safety functions in the station area.

________________________________________KAVACH Sub-system

The KAVACH sub-system consists of multiple electronic cards that perform safety-critical processing:

• PPC cards handle peripheral processing

• Vital Computer cards run the core safety logic

• Voter cards ensure redundancy and fail-safe decision-making

• IDL records all system operations

• GSM card supports wireless fallback communication

These modules are the brain of the system and ensure continuous safe operation.

________________________________________Connector Details

All cards are connected to the system through multiple pin connectors.

Most cards have one 28-pin and two 40-pin connectors, while IDL and GSM cards have one fewer 40-pin.

During maintenance, it is essential to ensure that:

All connectors are fully inserted

Locking arrangements are secured

No dust or oxidation is present

Improper seating of connectors is one of the most common causes of system failures.

________________________________________LED Indications

Each card is equipped with LEDs on its front fascia.

These LEDs show the real-time working status of the module.

During maintenance, observing LED patterns helps identify whether the module is healthy or faulty.

Fault localization always begins with LED diagnosis.

________________________________________Maintenance Assumption

During these maintenance steps, we assume that any fault is internal to the card being tested.

The external wiring, relays, and field devices are assumed to be healthy.

This helps narrow down the focus to only module-level troubleshooting.

________________________________________FIU Sub-rack

The FIU sub-rack contains FIU Scanner cards.

Each scanner card accepts 32 field inputs from the interlocking system.

Both front and back relay contacts can be used to provide status.

FIU continuously scans these relay inputs and updates the KAVACH processor in real time.

________________________________________Field Input Interface

The scanning voltage for all inputs is 24V DC, supplied from IPS through fuse protection.

Potential-free contacts from relays are fed to FIU.

Every single input is protected by an individual fuse — this simplifies troubleshooting.

Any fuse blown means a single input failure, not the entire rack.

________________________________________FIU Scanning Process

This slide shows the input path:

Relay Panel → KAVACH Signaling Relays → Input Fuses → FIU Scanner → KAVACH System

The objective is to ensure accurate detection of:

• Signal aspects

• Point status

• Track occupancy

Any delay or error here directly affects train movement safety.

________________________________________Power Supply Unit

Power is provided to the KAVACH system from 110V DC IPS supply.

This power is fed into Digital Power Supply (DPS) modules inside the KAVACH rack.

The DPS modules convert the 110V DC into regulated 24V DC for the electronic cards.

________________________________________Power Redundancy

KAVACH uses two DPS modules — DPS1 and DPS2.

If one DPS fails, the other continues to supply 24V DC without any downtime.

This redundancy ensures maximum system availability and safety.

________________________________________Maintenance Checklist

During routine inspections, technicians must verify:

MC10 main power connector is properly lockedJ2 connectors on DPS1 & DPS2 are secure

J8 and J9 power outputs are fully inserted

All 28-pin connectors are tight in placeAlways ensure MCBs are OFF and fuses are removed before working on power connections.

________________________________________Summary

To summarize today’s lesson:

• The Station Unit includes the KAVACH rack, FIU system, and power supply

• Continuous relay scanning enables accurate safety decisions

• Proper connector locking and power checks are critical

• Redundant power systems ensure fail-safe functioning

A reliable Station Unit ensures reliable train protection.

Modem Interfaces in KAVACH System

Today, we will discuss Modem Interfaces in the HBL KAVACH System, specifically the maintenance.
This topic is crucial because modems form the communication backbone between the station, locomotive, IB huts, and OFC huts.
Let’s begin.

Introduction

In the KAVACH system, modems are used in three main locations:

1. Inside the KAVACH unit

2. In the Location Box near the Radio Tower

3. In the OFC Hut for connectivity with the RAILTEL network

These modems are responsible for maintaining reliable communication between the loco and station, loco to loco, and between different station components like IB-Hut and OFC-Hut.

Understanding their maintenance is essential to avoid communication failures.

Types of Modem Connectivity in KAVACH Unit

Inside the KAVACH unit, there are three types of modem interfaces:

• Radio Modems: These handle communication to and from the locomotive.

• IB-Hut Modems: Used for receiving critical field data from the Intermediate Block Hut.

• OFC-Hut Modems: Connect the station KAVACH to the RAILTEL fiber network.

The PPC1 and PPC2 cards provide the interface for radio modems, while the IDL card provides Ethernet connectivity for OFC and IB Hut modems.

Radio Modem Connectivity

Let’s first understand radio modem connectivity.

These modems allow communication between the locomotive and the station, and also between two locomotives.

Each station KAVACH unit uses two radio modems, powered by 24V DC.

They are connected through RPS modules, surge protectors, LMR600 cables, and OFC modems located in the Location Box.

Because radio-based communication is vital for train safety, maintaining this link is extremely important.

Radio Modem Connectivity Path

This slide shows the complete connection path:

• PPC1 and PPC2 send signals to the Radio Power Supply Modules (RPS1 and RPS2) through the 40-pin connectors.

• These then supply power and communication links to the Radio Modems.

• From the radio modems, the signal goes to the Tx/Rx antennas via LMR600 cables and surge protectors.

• The entire setup connects to the Location Box through OFC modems.

All these points must be thoroughly checked during maintenance to ensure no loose connections.

Radio Modem Maintenance Checklist

During maintenance, the following checks must be performed:

• Ensure the 40-pin connectors on PPC1 and PPC2 are properly locked.

• Verify J1, J3, and J4 connectors on RPS modules are secure.

• Make sure the 25-pin D-sub connectors on both modems are locked properly.

• Confirm DB9 connectors from RPS modules are connected to the correct SETUP and DATA ports of the radio modem.

• Check OFC cables are properly seated.

• Verify the Tx and Rx antenna cables are connected to the right ports.

• Ensure power connectors are seated correctly.

Power checks are also important:

• The power LED on the radio modem must be ON.

• D1 LED on the RPS must be lit, indicating that 24V DC is available.

OFC-Hut Connectivity

This interface connects the KAVACH system to the RAILTEL network, which links stations and provides connectivity to the Network Management System.

The IDL card provides an Ethernet output to the Ethernet switch, which in turn connects to OFC-Hut modems.

OFC-Hut Maintenance Checklist

For the OFC-Hut connectivity, you must check:

• The Ethernet cable from the IDL port to the switch.

• Ethernet cables from OFC Modem 1 and 2 to the switch.

• Power connectors from DPS1 and DPS2 modules to the modems.

• CAT6 cable connected to the Line port of the OFC modem.

Any loose connection in this chain can interrupt communication with neighboring stations.

IB-Hut Connectivity

The IB-Hut modem interface connects the KAVACH system to the Intermediate Block Hut.

The IB Hut provides essential signaling data, and therefore a stable connection is crucial.

This interface also uses the IDL card, Ethernet switch, and modem, similar to the OFC-Hut setup.

IB-Hut Maintenance Checklist

The maintenance checks for IB-Hut modem connectivity include:

• Ensuring Ethernet cable from IDL to switch is connected properly.

• Ensuring Ethernet cable from modem to switch is locked.

• Checking power connectors from DPS1 and DPS2 to the modem.

• Checking CAT6 cable at the Line port.

If any of these links are disturbed, the system may fail to receive critical inputs.

Summary

To summarize:

• Modem connectivity is essential for safe communication in the KAVACH system.

• Always check connectors, Ethernet cables, power cables, antenna connections, and LEDs.

• Ensure all power outputs from RPS and DPS modules are normal.

• Proper modem maintenance ensures reliable loco-to-station and station-to-network communication.

A small loose connector can lead to major communication breakdowns, so detailed inspection is important.

Maintenance and Operation of Stationary KAVACH System

________________________________________

Today we are focusing specifically on the maintenance and operational aspects designed for S&T Team. The KAVACH system is a critical safety infrastructure, and understanding these procedures is paramount to ensuring safe and efficient railway operations. Let's begin.

________________________________________

Overview of Stationary KAVACH

The core purpose of KAVACH is Automatic Train Protection, a crucial layer of safety. This lecture will break down three key areas of the stationary system:

1. The Station Master Operator Panel, or SM-OCIP.

2. The strict earthing requirements necessary for reliable operation.

3. The specific tools and software, like the KAVACH Test Bench, that you will use during maintenance.

Our goal is to equip you with the knowledge needed to troubleshoot common issues effectively.

________________________________________

Station Master’s Operator Cum Indication Panel (SM-OCIP)

The SM-OCIP is your primary interface at the station level. It’s physically located in the Station Master’s room for easy access and monitoring. This panel doesn't operate standalone; it is connected directly to the main, outdoor KAVACH unit via a dedicated cable connection. It displays system status, indications, and, crucially, error messages that we need to interpret.

________________________________________

SM-OCIP Arrangement and Maintenance

As you can see in this typical arrangement diagram, the physical link is simple but vital.

The key takeaway for maintenance here is strictly physical. Your regular checks must include verifying that the connection cable between the main KAVACH equipment and the indoor SM-OCIP unit is not just plugged in, but properly locked in place. A loose connection is the most common and easily fixable cause of communication errors.

________________________________________

Error Messages on SM-OCIP - Part 1 (Hardware Errors)

The KAVACH system is designed to provide clear error codes. We can group these errors into two main categories.

The first category covers hardware failures, typically related to external connections or internal modules.

• Error 1 (GPS Failed): If the unit cannot obtain a GPS signal, it needs a full check of the antenna, cabling, and the internal GPS module.

• Error 2 (Radio Failed): Similar process for the radio unit. Check all physical connections and the antenna tower setup.

In both these cases, if the cables and connectors are fine, you are likely looking at replacing the specific defective module.

________________________________________

Error Messages on SM-OCIP - Part 2 (Software/Configuration Errors)

The second category of errors relates to configuration files. KAVACH relies on specific layout files: FIU (Field Interface Unit), Station Layout, and General Configuration Layout.

• Errors 3, 4, and 5 (FLF, SLF, CLF): When the system fails to load these files, the first step is always a simple system reset of the card. If the error persists after checking connections, the internal memory likely needs reprogramming using the KAVACH Test Bench software, which we’ll discuss shortly.

________________________________________

Earthing of Station KAVACH - Importance

Moving on to a critical infrastructure requirement: Earthing. Proper grounding is non-negotiable for railway S&T equipment. It protects the sensitive electronics from power surges, lightning strikes, and ensures a stable operating environment. We implement a common earth system for all KAVACH components.

________________________________________

Earthing Specifications

These limits are strict and must be adhered to during your maintenance cycles. The goal for the core equipment—the KAVACH unit itself, the terminal panels, and the RF tower legs—is a resistance of less than or equal to 1 Ohm (≤ 1 Ohm). The location box has a slightly relaxed limit of 2 Ohms, but the goal is always as low as possible. You must use a digital earth resistance tester to verify these values regularly.

________________________________________

KAVACH Test Bench Tool - Software

To perform advanced diagnostics beyond simple cable checks, you need specialized software: the KAVACH Test Bench Tool. This is a software application run on a standard laptop.

It allows you to test various sub-components of the KAVACH unit. While the main operating software inside the KAVACH unit is standardized, this test bench software lets us load and verify the application-specific data—the unique parameters for this specific station or locomotive. The user manual provides step-by-step procedures you will follow.

________________________________________

Tools Required for Maintenance Work

We have a standard list of physical tools required for any technician attending a KAVACH site. Most of these are standard items you use daily: digital multimeters, screwdriver sets, pliers, and a soldering iron. Ensure your kit is complete before dispatching for a maintenance job.

________________________________________

Specialized Tools & Equipment

In addition to standard hand tools, certain specialized items are required for KAVACH maintenance. These include connection cables like Ethernet and USB-to-Serial adapters for connecting your laptop to the KAVACH unit. You also need specific programming hardware like the J-Tag and ICD units for flashing firmware or configurations. And finally, the essential item: the laptop with the Test Bench Software application pre-installed.

________________________________________

Summary

To summarize: we maintain system health through routine physical checks of connections, prompt interpretation of error codes (hardware vs. software issues), strict adherence to earthing standards, and utilizing the Test Bench software for diagnostics and reprogramming.

Station Kavach System (Kernex Make)

Station Kavach System – Kernex Make

Today, we will learn about the Stationary Kavach System of Kernex Make, based on the Maintenance and Troubleshooting Manual for Stationary TCAS.

This session is part of your training module designed specifically for S&T Teams who will handle installation, maintenance, and troubleshooting of the Kavach system.

Let’s begin.

Kernex Station Kavach

The Kernex Station Kavach is generally installed inside the relay room, and it is responsible for ensuring safe train operations under TCAS.

This system consists of several important hardware modules:

• Power Supply Card,

• Microcontroller Intelligent Equipment (MIE) cards,

• GPS modules,

• Data Logger,

• Field Input Modules (FIM),

• Field Output Module (FOM).

These components are assembled in two distinct BINs:

1. Power Bin

2. Logic Bin

Each of these bins plays a specific role in power management, processing, and safety logic.

Power Bin Components

Now, let’s look at the Power Bin.

The Power Bin supplies all necessary DC voltages to the Stationary Kavach system:

1. FTM-S Filter Module – Removes noise and stabilizes input power.

2. Two redundant PSM1-S modules – These provide isolated and independent supply of 5V DC for Channel-1 and Channel-2.

3. One PSM3-S module – Supplies 24V DC required for Radio Modems.

4. Data Logger Module – Records all events, system status, and faults.

This bin ensures that even if one power channel fails, the system continues to operate safely.

Logic Bin Components

Next, we have the Logic Bin, which contains the main intelligence and control electronics.

This includes:

• Six MIE cards (MIE1 to MIE6) which handle processing and communication,

• Six Field Input Modules (FIM1 to FIM6) for reading interlocking inputs,

• One Field Output Module (FOM) for generating field outputs,

• Two Isolated Current Loop (ICL) cards,

• A GPS Interface Card housing two GPS receivers.

This bin handles the logic execution, data processing, and communication required for TCAS operation.

Hardware Architecture Overview

Now let’s understand how the hardware is architected.

Each FIM card reads 24 field inputs from the signaling system—such as signal aspects, point positions, and track occupancy.

FIM cards work in pairs:

• FIM1 & FIM2 share the same inputs,

• FIM3 & FIM4 share the same inputs,

• FIM5 & FIM6 share the same inputs.

This redundancy ensures fail-safe operation.

Data flows as follows:

• FIM1, FIM3, FIM5 → MIE1

• FIM2, FIM4, FIM6 → MIE2

MIE1 and MIE2 operate in a 2-out-of-2 architecture, meaning both must agree on the status for safe output.

Other MIE cards:

• MIE3 interfaces Radio Modem-1 and GPS-1,

• MIE4 interfaces Radio Modem-2 and GPS-2,

• MIE5 and MIE6 read remote field inputs from Automatic Sections, IBS, and LC Gates.

The Data Logger and SM-OCIP both communicate via MIE1 and MIE2.

MIE Card

Now we will discuss the MIE card, which acts as the processing brain of the system.

Each MIE card contains two microcontrollers, offering composite fail-safety.

It plays a crucial role in processing inputs and making decisions according to interlocking logic and TCAS requirements.

The card has several status LEDs:

• LED-5V indicates presence of 5V power.

• LED-3V indicates internal logic voltage.

• LED-ER indicates any error condition.

• LED-S1 and LED-S2 show program execution status.

The ISP port is used for loading firmware.
The LAN port is not used in stationary operation.

FIM Card

The Field Input Module or FIM card is responsible for reading field inputs from the signaling system.

FIM cards work with optical isolation to ensure electrical safety and noise immunity.

Key functions of FIM:

• Reads signal aspects

• Reads point machine statuses

• Reads berth track occupancy

• Provides 2-out-of-2 validation for safety

Each FIM supports 24 input channels.

LED indicators on FIM:

• LED-5V indicates supply to the card.

• LED-3V shows logic voltage.

• LED-24V indicates presence of 24V field input supply.

If any of these LEDs are OFF or flickering, it helps troubleshooting quickly.

End of Lecture

This concludes the lecture on Stationary Kavach System – Kernex Make.

In upcoming sessions, we will learn:

• Fault analysis,

• Troubleshooting procedures,

• Preventive maintenance schedules for the Kernex Kavach system.

Stationary KAVACH System – Electronic Cards & Modules

Today we will be covering an important part of the Stationary KAVACH System—its electronic cards and modules.
These components ensure reliable communication, synchronization, signalling, and data logging in the KAVACH architecture.
In this session, we will understand the purpose, indicators, and functionalities of each card used in the system.

Overview

In this module, we will discuss the following cards:

• Field Output Module (FOM)

• Isolated Current Loop (ICL) Card

• GPS Interface Module

• Filter Module (FTM-S)

• Power Supply Modules PSM1-S and PSM3-S

• And finally, the Data Logger
  Let’s go through them one by one.

FOM CARD

FOM Card

The Field Output Module is used to provide essential output indications.
This includes SOS status, buzzer output, and KAVACH OK or NOT OK indications.
All the outputs are provided through optically isolated solid-state relays, ensuring electrical isolation and safety.
Each FOM card supports up to 24 distinct output channels.

FOM Card Indicators

The FOM card contains multiple LED indicators.
These LEDs help technicians quickly diagnose power supply and output health.

• LED-5V indicates that the 5-volt input is present.

• LED-3V1 and LED-3V2 show the 3.3-volt operational voltage for the card.

• LED-24V indicates that the 24-volt output supply is available.

• LED-5V2 is a secondary 5-volt input indication.
  If any LED is OFF, it points to a specific power issue that must be corrected.

ICL CARD

Next is the Isolated Current Loop card.
This card isolates the serial communication channels using optical isolation.
Communication connections for Radio, Data Logger, and SMOCIP pass through this card.
The purpose is to ensure that electrical noise or ground differences do not affect data communication.

ICL Indicators

The ICL card also uses multiple LED indicators:

• LED-5V indicates the primary 5-volt input.

• LED-3V1 displays the 3.3-volt operating voltage.

• LED-5V I1 is not used.

• LED-5V I2 indicates the presence of an isolated 5-volt supply.
  These help you confirm proper isolation and power conditions.

GPS INTERFACE MODULE

GPS I/F Module

We now move to the GPS Interface Module.
Two GPS modules are stacked together to form a complete GPS I/F unit.
This card generates PPS-1 and PPS-2 signals, which are very precise timing pulses.
These PPS signals are required to synchronize radio communication data in MIE-3 and MIE-4.

GPS Indicators

This card has indicators for monitoring GPS power and pulse status:

• LED-5V 1&2 indicate the 5-volt power to both GPS modules.

• LED-3V1 1&2 show the operating 3.3-volt supply.

• LED-PPS-1 and LED-PPS-2 indicate the real-time pulse generation.
  The module also provides two connectors, GPS-1 and GPS-2, for connecting the respective antennas.

FTM-S MODULE

FTM-S Module

The Filter Module, or FTM-S, is essential for protecting all electronic modules.
It suppresses inductive noise generated by external field devices.
Without this module, noise may trigger false signals or damage sensitive electronics.

FTM Indicators

The FTM-S card has the following indicators:

• LED-24V1 I/P and LED-24V2 I/P for 24-volt inputs.

• LED-24V1 O/P and LED-24V2 O/P for 24-volt outputs.
  It also has two 10-amp fuses for Input 1 and Input 2.
  These LEDs and fuses help technicians easily identify faults in the input or output paths.

PSM1-S MODULE

PSM1-S Module

Next is the Power Supply Module PSM1-S.
This module converts the system’s 24-volt DC input into two 5-volt DC outputs.
One of the outputs is redundant, so if the primary output fails, the backup takes over.
The module accepts a wide voltage range of +30% to –20% at its input and has built-in protection against:

• Undervoltage

• Overvoltage

• Short circuit

• Overload

PSM1-S Indicators

The PSM1-S card includes:

• LED-24V1 and LED-24V2 for monitoring the input power

• LED-5V1 and LED-5V2 for monitoring the output health
  It also contains two 3-amp fuses on the input side.
  These indicators help ensure that the card is supplying stable 5-volt power to the rest of the system.

PSM3-S MODULE

PSM3-S Module

This power supply module derives two isolated 24-volt DC outputs from the same 24-volt input.
These isolated supplies are specifically used for powering the radio modems.
Like PSM1-S, it also supports the same voltage variation and protection features.

PSM3-S Indicators

The module includes LED-24V1 and LED-24V2 for input indication, and LED-5V1 and LED-5V2 at the output side.
Two 3-amp fuses are also provided on the input.
These indicators assist in ensuring that the radio modems receive clean, isolated power.

DATA LOGGER

Data Logger

Finally, we come to the Data Logger.
The Data Logger stores all event logs for both the Station KAVACH unit and the key management system.
Technicians can download event data using a USB pen drive for analysis.
This makes troubleshooting and incident investigation much easier.

Data Logger Interfaces

The Data Logger includes multiple interfaces:

• VGA port for connecting a monitor

• COM port for interfacing with the MIE

• USB port for pen drive data download

• PS-2 for keyboard

• SIM-1 and SIM-2 for SIM card insertion

• ANT-1 and ANT-2 for GSM antennas

• LAN port for NMS connectivity
  It also includes unused ports (S1 to S4) reserved for future expansion.
  The 5-volt indicator shows CPU power status.

Summary

To summarise, today we learned about all the major cards used in the Stationary KAVACH system.
Each module has a specific role—whether it is communication, power conversion, filtering, timing synchronization, or event logging.
Understanding these modules helps technicians troubleshoot issues effectively and maintain system reliability.

Maintenance & Trouble Shooting of Stationary KAVACH System (Kernex Make)

________________________________________

Good morning everyone.

In today’s session, we will discuss Maintenance and Troubleshooting of the Stationary KAVACH System of Kernex Make.

This is very important for S&T Teams, as it teaches you how to check system health, verify software, and download event logs.

________________________________________Overview

In this training module, we will cover:

• Maintenance tools required

• Test procedure

• Station KAVACH health status monitoring

• Software version checking

• Data downloading process

By the end of this session, you will be confident in carrying out basic diagnostics on the Stationary KAVACH Unit.

________________________________________

Station KAVACH System Maintenance

Let us start with the maintenance requirements.

For the Station KAVACH system of Kernex make, we use both software and hardware tools.

These tools allow us to check the condition of the MIE cards, communication, power supply, and field inputs.

________________________________________Software Tool

The main software tool used for maintenance is the Station KAVACH Maintenance Tool.

This tool helps us perform system diagnostics, health monitoring, view real-time data, and check software configuration.

________________________________________Hardware Tools

The hardware tools required are:

• A laptop for running the diagnostic software

• A multimeter for checking voltage and continuity

• A screwdriver set and Allen keys for opening panels

• USB to Serial cable

• ISP cable for connecting to MIE

These tools must always be available during any maintenance activity.

________________________________________

Test Procedure

Now let us look at the step-by-step test procedure.

1. First, connect your laptop to MIE-1 using the ISP cable.

2. Switch ON your laptop.

3. Open the Station Maintenance Tool application.

4. Enter the username and password:

o User: admin

o Password: admin@123

5. Click on ‘Login’.

After logging in, you will reach the main dashboard.

________________________________________Login Screen

This slide shows the login screen that appears when you launch the Station KAVACH Maintenance Tool.

This is where you enter your credentials.

________________________________________Main Screen

After logging in successfully, this is the main screen of the Station KAVACH Unit.

From here, you can access all maintenance functions like Health Status, Software Version Check, and Data Downloading.

________________________________________

Station KAVACH Health Status

To check the real-time health of the system, click on ‘Health Status’.

This is one of the most important diagnostic screens.

________________________________________Health Status Parameters

The Health Status screen shows several important system parameters:

• Active signals received from the field

• Track circuit information

• Point status

• Peripheral device status

• GPIO status

• MIE card status

• Data logger status

This helps the technician quickly identify any abnormal behaviour.

________________________________________Status Check Screens

These slides show examples of the Health Status screen.

Technicians should verify whether all inputs, outputs, communication links, and MIE cards are functioning normally.

Any field-related fault will be reflected on this screen.

________________________________________

Software Version Checking

Next, let’s look at how to check the software version.

Click on ‘Software Version Checking’.

This screen displays the Configuration CRC values.

CRC helps ensure that the software and configuration loaded in the system are correct and have not been corrupted.

________________________________________Software Version Screen

This slide shows the actual software version check screen.

During maintenance, always verify that the configuration CRCs match the master configuration approved by the division.

________________________________________

Data Downloading Process

The last important activity is data downloading.

Insert a pen drive into the Data Logger’s USB port.

Once inserted, the system will automatically show:

1. Device mounted

2. Log copy successful

3. Remove Pen Drive

This process ensures that all event logs are safely copied.

________________________________________Purpose of Data Downloading

Why is this important?

The event logs stored in the pen drive help:

• Diagnose failures

• Investigate incidents

• Understand system behaviour

• Provide data to higher-level teams for analysis

So data downloading must be done at regular intervals.

________________________________________Summary

To summarize, today we covered:

• Tools required for KAVACH maintenance

• How to connect and log in using the Maintenance Tool

• How to check the system’s health

• How to verify software versions

• How to download event logs

These procedures help ensure that the Stationary KAVACH system runs smoothly and safely.