380V factory motor low voltage protection circuit

Low voltage protection is under voltage protection. When the grid voltage drops to a certain value, the motor automatically stops
running through low-voltage protection. The wiring of motor low-voltage protection should ensure that it can reflect the corresponding voltage drop, and
should not malfunction when the voltage transformer is disconnected.
    When the motor is controlled by an AC contactor, since its coil can automatically release when the voltage is low, there is no need to install low- voltage protection .
    Figure 4-48 shows the low-voltage protection circuit of a 380V factory motor . It consists of 4 voltage relays 1KV~4KV
. The operating voltage of 1KV ~ 3KV is set to ensure the self-starting of important motors , and is taken as 0.7U. ; The operating voltage of 4KV is
(0. 4 ~ 0. 5) Ue.