The subject of this video class is control systems. I believe you are aware that the control system plays a crucial role in the electrical panels. That means without a control system, the electrical panel is nothing. So I am explaining here about control systems, how it is designed and why they are required,

In electrical panels, there are different types of equipment installed and each of which requires separate controls for operation.

The main circuit breaker of the MSB is an air circuit breaker, which requires a control system. Controls are used for the protection of over-current, short circuit and earth fault relays.

Control circuits are important in all types of electrical equipment. Each device has its own planned logic, which utilises different types of control components.

Prior to start the tutorial, we need to know about the components that used in the control system. Details of commonly used components in the control system are given below.

Control relay.

Control relays are electromagnetic devices used in a control circuit to control the current flow in the main circuit as per the logic.

The controllers of other devices operate through this relay according to the command from the logic.

Contactor.

The contactor is an electrically controlled switch used to apply electrical power to equipment. The contactors are designed to connect directly to low or high-load equipment.

Timers, on delay and off delay.

The timer is an integration of an electromechanical output relay that works in conjunction with the control circuit.

An electronically controlled timer is also available for different purposes.

Under-voltage relay.

An under-voltage relay operates when the voltage that flows through a relay's coil falls below a predetermined value.

Phase failure relay.

The phase failure relay monitors phase sequence, phase break and under-voltage.

The output relay is energised when all three-phase voltages are present and the phase conditions are correct.

There are also some other control devices used in the control area. Let us look at the details of such control devices related to control systems.

Limit switches.

A limit switch is used to control the movement of the equipment. For example, motor-operated equipment needs to stop when it reaches a pre-determined duration or destination.

Limit switch for the door

This switch is used to operate a device control with door opening and closing.

Limit switch for a moving machine.

This is used to control the movement of a moving device. This is used to control the movement of a section or part of a device.

Limit switch for pressure control.

This switch is used to control the movement of equipment by using pressure. This will sense the pressure of the movement and control the movements.

Foot switch.

Two types of foot switches are available.

This single-operation Foot switch is used to make the machine ON and OFF.

This foot switch has two pedals for double operation.

We learned about the general components and devices used in the control system of the electrical panel. The operation of normal motor control, starter, and the use of spare (latch) contacts.

Now we will start learning about different types of control used in circuits. Using variable control switches for the control of equipment.

Mainly, five types of control systems are commonly used in circuits, such as:

Local: The control devices are placed on the main enclosure.

Remote: The control devices are placed outside of the main enclosure, probably near the equipment.

Maintained: Re-energisation of equipment occurs automatically after a power failure.

Non-maintained: After a power failure, a new instruction is required to re-energise the equipment.

Inching: Also called Jog control. Pulse on the start button, commonly used in reversing starters.

Here, we will learn about the various modes of operation in a control system.

In general, there are three different operational modes available in controls. Such as single operation, multiple operation or parallel operation and sequential operation.

Single operation.

This mode of operation is used for the normal function of the equipment. For example, one motor is controlled through a starter from one station. The starter shall be any type according to the requirement.

Here is a sample drawing of starters to refer to the single operation.

Multiple or Parallel operations.

One equipment needs to operate from different places for some special requirements. In these cases, additional ON/OFF controls are provided in parallel with the main control of that equipment.

Sequential operation.

This mode of operation is used in a system where a step-by-step process of working is required. For example, these controls are used for production units which need operations in different steps or in different stages.

We will check the working method of a processing unit. Moving the raw materials from the receiving station to the production process through different steps. The first step is the incoming of material, the second/third is moving through the conveyors, and the fourth is entering the production unit.

I gave a picture of a simple processing unit to explain the sequential operation.

Stage - 1: Receiving the materials.

Stage - 2: Material moving through conveyor 1.

Stage - 3: Material moving through conveyor 2.

Stage – 4: Material reaches in processing station.

The automatic sequential control systems in the electrical panels. The following components used for automatic mode.

Emergency stop switch 1unit.

ON/OFF control switch 1unit.

ON delay, Timer with Normally Closed contact 1unit.

Pressure switch with Normally Open and Normally Closed contact 2 units.

Limit switch, with Normally Open contact 2 units.

Contactor 3units.

The other switches, used in the circuit, are three Interlocks with Normally Open contacts, from the same Contactors.

In this mode of operation, we have to energise the circuit's control power only to start the function. The path of control power looks as follows. As you know, only single-phase power is used in the control circuit to control the complete operation.

The power scheme is shown here in block diagram.

When the main power is ON, power reaches to emergency switch.

Then to the power ON – OFF switch.

From there, normally close contact of the ON-delay timer.

Then to pressure switch.

After Interlock 1 (N/O), limit switch 1 (N/O),

Interlock 2 (N/O of K2). Limit switch 2 (N/O).

Finally, to the ON-delay timer.

Subject of this video class is about control systems, I think you might be know that, the control system is acting is an important role in the electrical panels. That means without a control system the electrical panel is nothing. So I am explaining here about control systems, how it is designing and why it is required,

In electrical panels there have different types of equipment are installed and each of which requires separate controls for operation.

The main circuit breaker of the MSB is an air circuit breaker, which requires a control system. Controls are using for the protection of over-current, short circuit and earth fault relay.

Control circuits are important in all types of electrical equipment. The control of each device has its own planned logic, for which different types of control components are also used.

Control circuits are very simple, but it would be complicated if you do not know how it works. Understanding the control schematic diagram properly will make the control system easier.

In all control systems, only one phase line is used for the circuits, which will be very low voltage. The voltage normally used for the control circuit is AC or DC below 60 volts, which is very useful for maintenance, as it is not harmful to humans.

In this video, I am explaining about what is control circuits, how it works and how the control system is designing. Moreover, I have to understand the fact that each control have its own logic. So that if we know the logic of the controls, it will be easy to understand the control system.