It is a relay that operates when the voltage in the circuit reaches a predetermined value. Its structure is basically the same as the current relay, but the coil of the electromagnet has a lot of turns,
and it should be in parallel with the power supply when used. It is widely used in voltage loss (zero voltage) and undervoltage (low voltage) protection.
The so-called loss of voltage and under voltage protection is that when the power supply voltage is reduced too much or temporarily cut off for some reason, the motor will automatically disconnect from the power supply;
When the power supply voltage is restored, if the starting button is not pressed again, the motor cannot start by itself.
If it is not controlled by relay, but manually controlled by knife switch directly, because the switch is not opened in time during power failure, when the power supply voltage is restored, the motor will start by itself, which may
cause accidents. In addition, there is overvoltage relay, which is when the circuit voltage exceeds a certain value, because of the electromagnet suction and cut off the power relay,
it is used for overvoltage protection (such as protection of silicon tube and silicon controlled components).
[VIP第8年] 指數(shù):7
通過(guò)認(rèn)證 
