What are the differences among circuit breakers, contactors and relays?

In the power system, circuit breakers, contactors and relays are all familiar devices to everyone. But if we dig deeper, we will find that we only have a vague understanding of them. Many people don’t know exactly what the differences are among these things and how they are related. Today, let’s talk about them together.
Let’s start with the common points!
Of course, without any doubt, these guys are all types of switch devices. What is a switch? This makes it easier to understand. Anything that can perform the action of opening and closing is a switch. Therefore, these things are all switches.
Therefore, these so-called differences are merely variations in the form of the switch.
So, do you think everyone will be able to understand it easily now?
1. Circuit Breaker
Its definition is quite simple: It refers to a switch device that can close, carry and break the current under normal circuit conditions, and can also close, carry and break the current under abnormal circuit conditions within the specified time.
II. Contactor
A contactor is an electrical device in industrial circuits that uses an electric current flowing through a coil to generate a magnetic field, causing the contacts to close, thereby achieving the control of the load.
III. Relay
A relay is an electrical control device. It is an electrical appliance that, when the input quantity (excitation quantity) changes to a certain extent, causes a predetermined step change in the controlled quantity in the electrical output circuit.