Electromagnetic relay, also known as relay, is one of the most important
devices in use today in various applications. For instance, when you turn the car engine on,
you use a relay, an electrically controlled switch.
In the following diagram, the purple cylinder,
the coil around it and the green shaft make the actual relay. This
circuit is used to turn the power on the 'High- Powered motor that is connected
to black terminals.
Since the motor work on a dangerously high
voltage, it is not sensible to manipulate such a thing directly; so, we assign
the job to our invisible hand - the relay. It acts on a very low
voltage and poses no threat to those who handle the High- Powered
When the switch is on, the purple
cylinder becomes an instant electromagnet and it attracts the green shaft. Then
the two black rods come into contact and the motor is turned
So, we can handle the motor through
the electromagnetic relay.
The following animation shows how it
Please answer the following questions.
- Discuss the use of electromagnetic relay in various applications.
- Describe in detail the mechanism of a circuit-breaker. Discuss the role
played by the solenoid in the device. How do you reset it, once activated?
- A simple relay circuit is used to activate a burglar alarm that has been connected to a window. Draw an appropriate circuit diagram to illustrate this.
- In car factories, relay circuits play a very prominent role. Discuss this.