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Power Supply for Railway Signalling (Indian Railways)
Rating: 5.0 out of 5(1 rating)
2 students
Created byB Thankappan
Last updated 8/2025
English

What you'll learn

  • INTEGRATED POWER SUPPLY SYSTEM
  • SECONDARY CELLS
  • LOW MAINTENANCE LEAD ACID CELLS
  • POWER SUPPLY ARRANGEMENTS
  • POWER SUPPLY LOAD CALCULATIONS
  • Earth Leakage Detector

Explore related topics

Course content

3 sections • 15 lectures • 1h 53m total length

  • Secondary Cells5:57

    Secondary Cells


    Today, we will begin first lecture, which is about Secondary Cells.
    This is an important topic, especially in the context of Signaling and Telecom Installations where backup power is critical.

    Introduction

    Secondary cells are devices that store electrical energy and supply it when needed.
    Because they can store energy, they are also referred to as Storage Cells or Accumulators.
    These cells operate on the principle of reversible chemical reactions.
    In simple terms, they convert electrical energy into chemical energy during charging, and back into electrical energy during discharge to power an external circuit.
    Their primary application in railways is to ensure uninterrupted power to signaling and telecom equipment during AC power failures.

    Types of Storage Batteries

    Now, let's look at the commonly used types of storage batteries.
    There are two broad categories:
    First, the Lead Acid Batteries, which include:

    • Conventional Flooded types,

    • Low Maintenance types, and

    • Valve Regulated types, also known as Maintenance-Free Batteries.

    Second, we have Alkaline Batteries, which include:

    • Nickel Cadmium,

    • Nickel Iron, and

    • Silver Zinc batteries.

    Lead Acid Batteries in Railways

    In signaling applications, especially in 25kV Railway Electrification (RE) areas, the use of Maintenance-Free Valve Regulated Lead Acid (VRLA) batteries is permitted.
    This is as per specification IRS:S 93/96(A) and was formalized by the Railway Board's letter dated 20th December 2010.
    These batteries require less maintenance and are better suited for demanding environments.

    Charging of a Cell

    Let's now understand how a cell is charged.
    During charging, current flows into the cell, and within the cell, the current moves from the positive plate to the negative plate.
    This process restores the chemical energy inside the cell, preparing it for the next use.

    Discharging of a Cell

    On the other hand, during discharge, the cell supplies current to an external circuit.
    Here, the current flows from the positive plate to the negative plate externally, and inside the cell, the flow is from the negative plate to the positive plate.
    Understanding the direction of current flow is crucial for correct application and troubleshooting.

    Capacity of the Cell

    Now, coming to the capacity of a cell.
    Capacity refers to the total amount of current a cell can deliver over a period of time, and it is expressed in Ampere Hours (AH).
    The capacity depends on several factors:

    • The type of cell,

    • The thickness of the plates,

    • The construction quality of plates, and

    • The overall size of the cell.

    Example of Capacity

    For example, a battery rated at 80 Ampere Hours can supply 8 Amps of current for 10 hours.
    When selecting a battery for an application, we must calculate based on the load current and the required backup time.

    Available Cell Capacities

    In signaling applications, especially using flooded type lead-acid cells, standard capacity ratings are available.
    These are 40AH, 80AH, 120AH, 200AH, 300AH, 400AH, and 500AH.
    Selecting the right capacity ensures reliability and longer operational life.

    Summary

    To summarize:

    • Secondary cells are vital for backup power systems.

    • There are different types available depending on the application.

    • Understanding charging, discharging, and capacity is essential to maintaining system reliability.

  • Battery Basics - Secondary Cell Characteristics and Performance Parameters7:12

    Secondary Cell Characteristics and Performance


    Today, we’ll be exploring key performance parameters of secondary cells, including Depth of Discharge, Capacity Assessment, Self-Discharge, and Efficiency.
    Understanding these concepts is essential for ensuring the optimal performance, reliability, and lifespan of battery systems—especially in backup and power-critical applications.

    Depth of Discharge (DOD)

    Let’s begin with Depth of Discharge, or DOD.
    DOD refers to how much of a battery's total capacity has been used up, expressed as a percentage.
    Secondary cells, like lead-acid batteries, should not be fully discharged—this is technically discouraged. Why?
    Because full discharge increases internal resistance, requires higher charging current for the next cycle, and most importantly, reduces the battery’s lifespan.

    Different battery types have different DOD limits:

    • Flooded Lead-Acid: 70%

    • LMLA (Low Maintenance Lead Acid): 80%

    • VRLA (Valve Regulated Lead Acid): 50%
      These limits are determined based on design, chemistry, and behavior over charge/discharge cycles.

    DOD – Key Takeaways

    Remember:
    As batteries age or due to manufacturing variations, the effective DOD can change.
    That’s why it's important to monitor usage and ensure we don’t discharge beyond the recommended limits.
    Consistently deep discharges shorten battery life and degrade performance significantly.

    Required Capacity Calculation

    Now that we understand DOD, let’s apply it in real-world sizing.
    The capacity we need from a secondary cell depends on how long we want it to supply power and how much current it needs to support.

    We use this formula:
    C = (Load Current × Backup Time) / Depth of Discharge

    For example, if our system needs 10 amps for 10 hours, and we’re using a Flooded Lead-Acid battery with a 70% DOD:
    C = (10 × 10) / 0.70 = 142.8 AH
    Since we don’t want to undersize, we’ll select the next higher standard capacity—200 AH in this case.

    Self-Discharge of the Cell

    Let’s now look at self-discharge, a phenomenon where the battery loses charge over time even when it's not connected to any load.
    This happens due to internal chemical reactions.
    Though inevitable, the rate of self-discharge varies by battery type and storage condition.

    A key way to reduce this loss is to store batteries in cooler environments, which slows down these chemical reactions and helps preserve stored energy longer.

    Efficiency of a Cell – Overview

    Battery efficiency is how well it stores and returns energy.
    We look at it from three perspectives:

    1. Ampere-Hour Efficiency

    2. Voltage Efficiency

    3. Watt-Hour Efficiency
      Let’s break each one down.

    Ampere-Hour Efficiency

    Ampere-Hour Efficiency is the ratio of the amp-hours discharged to the amp-hours used to recharge the battery.
    This typically ranges between 85% to 90% for lead-acid batteries.

    Why is it not 100%?
    Because of energy losses during charging—primarily due to gassing.
    To reduce these losses, we must avoid excessive charging current, which increases gassing.

    Voltage Efficiency

    Voltage Efficiency compares the average voltage during discharge with that during charge.
    For this to be accurate, both charge and discharge must occur at the same current and over equal time durations.
    This is more of a theoretical measure but still useful in understanding energy losses due to internal resistance and chemical lag.

    Watt-Hour Efficiency

    Finally, Watt-Hour Efficiency combines both amp-hour efficiency and voltage efficiency.
    The formula is:
    Watt-Hour Efficiency = AH Efficiency × (Avg. Discharge Voltage / Avg. Charge Voltage)

    This is always less than AH efficiency because it factors in both current and voltage losses.
    It usually ranges between 70% to 80% for lead-acid cells.

    Summary

    To summarize:

    • Never fully discharge a secondary cell—follow the recommended DOD.

    • Calculate required capacity using load current, backup time, and DOD.

    • Account for self-discharge during storage, and store cells in cool places.

    • Monitor efficiency—especially watt-hour efficiency—as it reflects actual usable energy.

    Understanding these principles ensures we design and use battery systems more effectively and extend their operational life.

  • Lead Acid Cell (Conventional Flooded Type)7:14

    Lead Acid Cell (Conventional Flooded Type)

    Today, we’re going to dive into the Lead Acid Cell, specifically the Conventional Flooded Type.
    We’ll cover its construction, types, chemical reactions during charging and discharging, and how to interpret its performance using specific gravity.

    Introduction to Lead Acid Battery

    A lead acid battery is an electrochemical device.
    It stores electrical energy in chemical form and uses lead, its derivatives, and sulfuric acid as main components.

    The anode, or positive plate, is made of lead peroxide (PbO₂),
    The cathode, or negative plate, consists of spongy lead (Pb),
    And the electrolyte is diluted sulfuric acid (H₂SO₄).

    Construction of Lead Acid Cell

    Both plates are supported by a grid made of pure lead or a lead alloy, which also conducts current.

    Key construction features:

    • Positive Plate: Lead Peroxide (PbO₂)

    • Negative Plate: Spongy Lead (Pb)

    • Electrolyte: Diluted sulfuric acid

    • Vent Cap: Allows gas escape during charging

    • The electrolyte level should always be 12 to 15 millimeters above the plates.

    Types of Lead Acid Batteries

    There are two main types based on positive plate design:

    1. Flat Pasted Plate Type:

      • Heavy-duty and rugged

      • Grid filled with a special paste of active material

    2. Tubular Type:

      • Positive plate has multiple tubes filled with lead oxide

      • More efficient, uses less lead

    In both types, the negative plates are the same.

    Cross-Sectional View (Illustration)

    Here is a cross-sectional diagram of a lead acid cell.
    You can see the arrangement of:

    • Positive and negative plates

    • Electrolyte

    • Vent cap

    • Plate connection bars: one for anode, one for cathode

    Notice that the outer plates are always negative, and there’s one extra negative plate to balance the surface area.

    Chemical Reactions – Discharging

    During discharging:

    • At the anode (PbO₂):
      PbO₂ + H₂SO₄ → PbSO₄ + H₂O + (O⁻)

    • At the cathode (Pb):
      Pb + H₂SO₄ + (O⁻) → PbSO₄ + H₂O

    • Overall:
      PbO₂ + Pb + 2H₂SO₄ → 2PbSO₄ + 2H₂O

    This reaction produces electrical energy as both electrodes form lead sulfate and water is generated.

    Chemical Reactions – Charging

    When the battery is charged, the reaction is reversed:

    2PbSO₄ + 2H₂O → PbO₂ + Pb + 2H₂SO₄

    • The lead sulfate on the plates converts back to lead peroxide and spongy lead

    • Sulfuric acid concentration increases

    • Energy is stored in chemical form again

    Charging and Discharging Overview

    Let’s summarize:

    (a) During discharge, sulfuric acid is consumed, and plates turn into lead sulfate.
    (b) During charge, lead sulfate converts back to active materials, and sulfuric acid is regenerated.
    (c) Near full charge, the current electrolyzes water, releasing oxygen at the positive and hydrogen at the negative plate — this causes water loss.
    (d) That’s why we need to top up the battery with distilled water regularly.

    Electrolyte Level and Plate Design

    A few more structural points:

    • One extra negative plate balances surface area.

    • Plates are welded to bars: one for the anode and one for the cathode.

    • The electrolyte must always cover the plates: maintain it 12 to 15 mm above.

    • Vent caps allow gas to escape and prevent pressure buildup.

    Importance of Specific Gravity

    Specific gravity of the electrolyte is a key indicator of battery charge.

    Let’s look at typical values:

    Condition

    Voltage

    Specific Gravity

    Fully Charged

    2.2 V

    1215 at 27°C

    Discharged

    1.8 V

    1180

    Max Conductivity

    —

    1240 at 27°C

    • Specific gravity decreases during discharge

    • It increases during charging

    • Temperature affects readings:
      Sp. Gravity at T°C = Sp. Gravity at 27°C – [(T – 27) × 0.7]

    Key Observations

    To ensure battery health:

    • Always top up with distilled water, not tap water.

    • Use a hydrometer to check specific gravity.

    • Keep an eye on vent caps for gas release.

    • Temperature correction is essential for accurate gravity readings.

    Summary

    Let’s summarize:

    • Lead acid batteries are rechargeable and use Pb, PbO₂, and H₂SO₄.

    • Chemical reactions during charge and discharge convert energy back and forth.

    • Specific gravity tells us the charge level.

    • Regular maintenance ensures long life and efficiency.

  • Charging and Maintenance of Secondary Cells7:43

    Charging and Maintenance of Secondary Cells


    Today, we are going to discuss a very critical topic in power maintenance and reliability—Charging and Maintenance of Secondary Cells.
    This includes the safe preparation of electrolytes, initial charging procedures, equalising charges, and limitations of conventional lead-acid batteries.

    Charging of Secondary Cells – Overview

    To begin with, charging secondary cells, or rechargeable batteries, is not just about connecting a charger.
    We must follow a disciplined and safe process.
    The best practice is to strictly follow manufacturer’s instructions.
    But if these are not available, we have a standard, reliable method which I’ll explain step by step.

    Mixing Electrolyte – Procedure

    Let’s now understand the electrolyte mixing process:

    • Always add acid to distilled water, and never the reverse. This avoids splashing and violent reactions.

    • Stir the mixture continuously using a wooden or glass rod, not metal.

    • Temperature must be carefully monitored—it must never exceed 45°C.

    • Once mixed, let it cool for 10 to 12 hours before use.

    • After cooling, measure the specific gravity. It should be 1190–1200 at 27°C, with corrections applied if temperature differs.

    Electrolyte Mixing Ratios

    This table shows the acid-to-water mixing ratios depending on the required and starting specific gravities.
    Please note these ratios carefully. For example, to get a specific gravity of 1190 from concentrated acid (1825), the correct ratio is 1:5.

    Initial Cell Preparation

    Once the electrolyte is ready:

    • Clean new cells thoroughly using distilled water.

    • Fill them with the prepared electrolyte.

    • Ensure electrolyte level is 12 to 15 mm above the plates.

    • Pay special attention to polarity when connecting the charger—positive to positive, negative to negative—to avoid dangerous short circuits.

    Initial Charging Process

    The initial charge is crucial for battery performance and life:

    • Charge the cells for 35 hours using a current equal to 4% of their ampere-hour capacity.

    • Take readings every 8 hours.

    • Charging continues until the specific gravity reaches 1210 ± 5.

    • If it doesn’t, adjust with higher Sp.Gr. electrolyte (around 1400) and recharge for 2 more hours to ensure thorough mixing.

    Charge-Discharge Cycle

    To stabilize the battery, we must also do a controlled discharge:

    • Discharge through a suitable resistive load (like lamps) until:

      • Sp.Gr. drops to 1180–1190

      • Voltage reaches 1.8 V per cell

    Repeat this charge-discharge cycle once more and then charge fully for actual use.

    Equalizing Charging

    Let’s talk about Equalizing Charging—also known as Boost Charging:

    • If batteries are idle for more than 15 days, or if they’ve been in float charge for 3 months, an equalizing charge is required.

    • Use a current of C/10 and monitor until voltage and Sp.Gr. remain stable over 3 consecutive 30-minute readings.

    • The aim is to bring voltage to 2.2V per cell and Sp.Gr. to 1210 ± 5.

    Final Steps and Precautions

    After charging:

    • Apply petroleum jelly or non-oxidizing grease on connections to prevent corrosion.

    • Close all vent caps securely.

    • Ensure the float indicators are showing proper electrolyte levels.

    Charger Settings

    Here’s a quick reference for charger settings:

    Charging Mode

    Voltage per Cell

    Current

    Float Mode

    2.25 V (adjustable)

    —

    Boost (Equalising)

    2.4 V

    10% of AH

    Initial Charging

    2.7 V

    4% of AH

    Make sure you set your charger appropriately depending on the charging mode in use.

    Codal Life of Secondary Cells

    The codal life, or expected operational life, of a standard secondary cell is 4 years.
    Proper maintenance and charging procedures are essential to ensure that these batteries live out their full useful life.

    Limitations of Conventional Lead-Acid Cells

    Despite their widespread use, conventional lead-acid cells do have limitations:

    • They require frequent topping up with distilled water.

    • Acid fumes emitted during charging can be corrosive and harmful, affecting nearby equipment.
      Thus, they should always be stored in a ventilated room with exhaust facilities.

    Alternatives to Conventional Cells

    To overcome these limitations, two improved variants have been developed:

    1. VRLA (Valve Regulated Lead Acid) Cells – These are sealed and require minimal maintenance.

    2. Low Maintenance Lead Cells – Covered in our next session.

    These modern alternatives offer better safety, reliability, and convenience.

    Summary

    To summarize:

    • Follow either manufacturer’s instructions or the standard method we covered today.

    • Always use proper safety gear and non-metallic tools.

    • Monitor specific gravity, voltage, and temperature at every stage.

    • Be mindful of the limitations of conventional cells and consider alternatives when suitable.

  • Low Maintenance Lead Acid Cells9:09

    Low Maintenance Lead Acid Cells

    Today we’ll be diving into Low Maintenance Lead Acid Cells, based on the Indian Railway Specification IRS: S-88/2004. These batteries are a significant improvement over conventional lead-acid types, especially in minimizing maintenance needs and water evaporation.

    Introduction

    Traditional lead-acid batteries suffer from a common problem—water evaporation due to gas formation. This leads to frequent topping up and high maintenance. The Low Maintenance Lead Acid or LMLA cells address this issue through technological enhancements. Let’s explore how.

    Features of LMLA Cells

    First, these batteries use a low-antimony alloy. This reduces gas formation during charging, which in turn reduces water loss. They're housed in tough, structurally molded polypropylene containers—PPSFM. Also, they utilize heavy-duty tubular plates, giving an excellent cycle life: 1500 cycles at 80% depth of discharge and up to 5000 at 20%.

    Features of LMLA Cells

    Other features include a low self-discharge rate—less than 3% per month at 27°C. They can also tolerate operation in a partially charged state, support deep cycling, and offer high ampere-hour and watt-hour efficiency. The codal life or designed service life of a secondary cell is 4 years.

    Benefits of LMLA Cells

    Thanks to those features, we get multiple benefits: higher reliability and trouble-free performance, reduced maintenance costs, and long cycle life. They’re particularly useful for deep discharge applications and can tolerate high temperatures, making them suitable for various environments.

    Chemical Reactions

    Let’s take a look at the chemical reactions involved. During discharge at the positive electrode, lead dioxide reacts with sulfuric acid and electrons to form lead sulfate and water. At the negative electrode, lead reacts similarly. Overall, lead dioxide and metallic lead react with sulfuric acid to form lead sulfate and water. These reactions reverse during charging.

    Electrolyte Filling

    Electrolyte preparation is critical. We use sulfuric acid with a specific gravity of 1.180 ± 0.005. Fill the electrolyte through the vent hole up to the green mark on the float guide. After filling, allow the cells to soak for 8 to 12 hours before charging. If the level drops, top up with the same specific gravity electrolyte.

    Electrolyte Quantity Table

    Here’s a table showing the amount of electrolyte needed for different battery capacities. For example, a 100 AH cell requires 4.8 liters of acid. This helps ensure optimal performance and longevity of the battery.

    Safety Precautions

    Always follow safety measures: wear rubber gloves, shoes, and eye protection. One critical rule—never add water to acid, always add acid to water to avoid dangerous splashing. Also, allow the electrolyte to cool to room temperature before beginning initial charging—and do this within 24 hours of filling.

    Initial Charging Procedure

    Initial charging is done in two phases. Start by charging at 10% of rated capacity until the cell reaches 2.4 volts. Then switch to 5% current until voltage reaches 2.65 to 2.75 volts. Stop when both voltage and specific gravity remain constant over three hourly readings. Add distilled water if specific gravity exceeds 1.200; if it stays below 1.200 after 60 hours, correct with 1.400 acid.

    Initial Charging Monitoring

    Monitor the entire charging process carefully. Record cell voltage, current, specific gravity, and temperature. Stop charging if temperature exceeds 50°C—resume only after it drops to 40°C. After 80% of input capacity, take hourly readings. Ensure all cells are gassing uniformly; if not, troubleshoot those cells and continue charging until they're fully charged.

    Battery in Operation

    Once charged, connect the battery to the load and charger. In standby mode, the charger supplies current and keeps the battery topped up via float charging. When there's a power failure, the battery automatically takes over the load.

    Float Charging

    Float charging keeps the battery fully charged without overcharging. Maintain float voltage between 2.15 and 2.20 volts per cell. Adjust float current as per battery capacity. For example, a 100 AH cell requires between 100 to 400 milliamps. Excessive voltage increases water consumption; too low voltage can reduce battery capacity.

    Weekly Maintenance

    Each week, check the pilot cells—one selected out of every 60 cells. Measure temperature and specific gravity. If the specific gravity is found low, the battery must be given a full charge to restore capacity.

    Recharging Procedures

    There are two charging methods: normal and boost. For normal charging, begin at 10% capacity until the cell reaches 2.4V, then reduce to 5% capacity until voltage reaches 2.65 to 2.75V. Terminate when voltage and specific gravity are stable for three hours.

    Boost Charging

    Boost charging is used when faster charging is needed. It’s done at 12.5% of rated capacity for 10 to 12 hours. This is helpful during maintenance or if the battery has been discharged significantly.

    Summary

    To summarize: LMLA cells offer a practical solution to the limitations of traditional batteries. With long life, high efficiency, and minimal maintenance, they are ideal for modern backup and cyclic applications. But proper filling, charging, and monitoring are essential for best performance.

  • Valve Regulated Lead Acid (VRLA) Batteries9:20

    VRLA Batteries (IRS Spec S 93/96(A))

    Today we’ll be discussing Valve Regulated Lead Acid Batteries, or VRLA batteries, based on IRS Specification S 93/96(A).
    We’ll look at their working principle, types, design features, charging methods, and both their advantages and disadvantages. Let’s begin.

    Introduction

    VRLA batteries are an advanced form of lead-acid battery that work on the oxygen recombination principle.
    They come in two main types:

    1. Gelled electrolyte

    2. Absorbed Glass Mat, or AGM
      Although their electrode reactions are the same as conventional flooded cells, their design eliminates water loss during charging, making them maintenance-free.

    Why VRLA?

    Unlike conventional batteries, VRLA cells don’t require topping up with distilled water.
    Under normal conditions, no equalizing charge is required, and their sealed design makes them spill-proof and safe for indoor use.
    In short, they’re compact, reliable, and low-maintenance.

    Working Principle

    Let’s understand the basic principle.
    When the battery charges, the positive plate produces oxygen gas. Instead of letting this gas escape, VRLA design channels it to the negative plate.
    At the negative plate, oxygen reacts with lead to form lead oxide, which then reacts with sulfuric acid to produce water.
    This cycle regenerates water lost during charging, preventing hydrogen evolution and making the battery self-sustaining.

    Oxygen Recombination Mechanism

    Here’s the chemical sequence:
    At the positive plate, water breaks down to release oxygen, protons, and electrons.
    At the negative plate, lead reacts with the oxygen to form lead oxide.
    Lead oxide then reacts with sulfuric acid to form lead sulfate and water.
    The overall effect is that oxygen is recombined into water instead of being lost as gas.
    This is the heart of VRLA technology.

    Gel vs AGM

    In gelled electrolyte batteries, oxygen travels through a fissured gel medium to reach the negative plate.
    In AGM batteries, the electrolyte is held in a highly absorbent glass mat separator, which is not fully saturated, leaving pathways for oxygen to move.
    Both designs achieve the same goal — oxygen recombination — but by different physical means.

    Special Design Features

    VRLA batteries include several clever design features:

    • Starved electrolyte: just enough electrolyte for performance, reducing leakage risk.

    • 99% recombination efficiency.

    • Explosion-resistant vents: release gas at about 6 psi and then reseal.

    • Hermetic seals to prevent leaks.

    • Superior alloys for better corrosion resistance and deep-discharge capability.

    • Copper insert terminals for better conductivity.

    • Modular trays for flexible installation.

    Charging Parameters

    These are critical to battery life:

    • Fully charged cell = 2.2 V

    • End point voltage = 1.75 V

    • Boost charge = 2.3 V/cell for 16 hours

    • Float charge = 2.25 V/cell

    • Current limit = 20% of rated ampere-hour capacity
      Always use constant voltage charging.

    Charging Types

    Three key charging scenarios:
    Freshening charge — before installation if voltage drops below 2.1 V per cell.
    Equalizing charge — every 6 months or when cell voltage variation exceeds 0.1 V.
    Normal charging — always in constant voltage mode.
    Never use constant current charging with VRLA.

    Safety Precautions

    Safety first:

    • Wear PPE — gloves, safety shoes, eye protection.

    • Use insulated tools.

    • Always work on an ungrounded battery.

    • Ensure correct polarity before charging.

    • Tighten connections to the specified torque — 10 Nm.

    Performance Monitoring

    Check monthly:

    • Overall battery voltage on float.

    • Individual cell voltages.

    • Terminal torque and cleanliness.
      Use a calibrated digital voltmeter with ±0.05 V accuracy.
      Keep records for long-term performance tracking.

    Temperature Effects

    VRLA batteries like it cool — 27°C is optimal.
    Higher temperatures shorten life dramatically.
    As a rule, for each 10°C increase, battery life halves.
    For high temps, reduce float voltage by 3 mV per cell per degree above 27°C.

    Advantages

    Some key benefits:

    • Long life due to high-quality alloys.

    • Compact and lightweight — 40% less space, 30% less weight.

    • No acid spillage or fumes.

    • High charge acceptance, low self-discharge.

    • Suitable for deep and partial discharges.

    Other Advantages

    In addition:

    • Uniform discharge current.

    • No stratification of electrolyte.

    • No corrosion from acid mist.

    • Works in extreme climates from -40°C to +55°C.

    • Lower running costs — no water topping or periodic equalizing charge.

    Disadvantages

    But nothing is perfect:

    • Sensitive to high temperatures — capacity halves with every 10°C rise.

    • Higher cost compared to conventional batteries.

    • Less ideal for outdoor high-heat environments.

    Summary

    To sum up:
    VRLA batteries are safe, clean, and reliable energy storage devices.
    They work on the oxygen recombination principle, which makes them maintenance-free.
    With proper charging, temperature control, and monitoring, they offer long service life, especially in critical indoor applications.

Requirements

  • Basic Knowledge of Railway Signalling System

Description

Power Supply System for Railway Signalling Applications

In modern railway networks, a reliable and uninterrupted power supply is the backbone of safe and efficient train operations. Signalling systems — whether traditional relay-based or advanced electronic interlocking — depend on precisely engineered electrical power arrangements to function without failure. This course is designed to provide a comprehensive understanding of the design, operation, maintenance, and troubleshooting of power supply systems specifically tailored for railway signalling applications.

Through a structured and practical approach, you will explore:

· Secondary Cells & Batteries — including lead-acid, low-maintenance, and VRLA technologies, their charging/discharging characteristics, efficiency, maintenance practices, and lifespan.

· Integrated Power Supply (IPS) Systems — components, working principles, SMPS-based designs, protection features, and problem-solving strategies.

· Power Supply Arrangements — sources, auxiliary transformers, changeover systems, load distribution, and maintenance responsibilities.

· Load Calculations — accurate methods to calculate DC, AC, and IPS loads for various signalling installations.

· Protection Systems — earthing, lightning and surge protection, transient suppression, and safe bonding practices.

· Solar Applications — harnessing renewable energy for signalling power requirements.

· Testing & Commissioning Procedures — including pre-commissioning checklists, performance monitoring, and preventive maintenance routines.

By the end of this course, you will be equipped with the knowledge to:

· Understand the complete power architecture for signalling installations.

· Select, operate, and maintain power equipment as per railway standards.

· Identify and resolve common faults to ensure uninterrupted signalling operation.

· Apply best practices for safety, efficiency, and long-term reliability.

Whether you are a railway signalling engineer, maintenance supervisor, trainee technician, or an enthusiast seeking deep technical insight, this course provides a solid foundation and practical skills for managing railway power supply systems.

Who this course is for:

  • Railway Signal Engineers
  • Railway Signal Technicians
  • Students and Academics
  • Technology Enthusiasts
  • Railway Operations Managers
  • Railway Professionals
  • ADSTE
  • JE Signals
  • SSE Signals
  • Tech -1 Signals

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