In the power system, circuit breakers, contactors and relays seem to be familiar to people, but many people know little about them, but they do not know the difference and what the connection is. Let’s talk about them.

First, the similarities! Of course, that is to say, these are all switches, and it’s easier to understand what a switch is, the thing that can perform a switch action is a switch, so these things are switches. Therefore, these so-called differences are only expressed in different forms. So it’s easy for everyone to understand, right?

First, the definition of circuit breaker is very simple: it refers to the normal circuit conditions, can turn off, load, current switching device, in the specified time, can turn off the current and load, in abnormal circuit conditions off the current.

Second, contactor refers to the use of coil current in industrial power to generate a magnetic field, so that contacts can be closed to control the load.

Third, “relay” is an electrical control device, when the input (excitation) changes to meet the specified requirements, so that the controlled amount in the electrical output circuit according to the predetermined steps of change.

As you may already know from the above modules, circuit breakers and relays are used in primary circuits and can turn on and off large currents, while relays are used in secondary circuits with small contacts and can only turn on and off small currents.

So what’s the difference between a circuit breaker and a contactor?

As you can see, the circuit breaker protects the current, overvoltage, etc., but the contactor controls how the motor works when the coil is opened according to different starting signals.

In short, the power system is actually very simple, namely the power supply, transformers, conductors, electrical equipment and switches, all complex circuits can be decomposed into the above four parts.