OEM ODM 60mm BLDC motor 48V 300W with RV30 worm gear from Bobet brand

There are many protection methods for three-phase motor in open-phase operation, some of which use the principle of voltage change and some of which use the principle of current change. This changing voltage or current is the trigger signal of the interlocking protection device for open-phase operation. Once the open-phase operation occurs, the power supply can be cut off quickly, so as to protect the motor and avoid accidents.
Using voltage change can be divided into two categories: using the neutral point voltage change of motor and using the line voltage change. When the motor is running normally, the neutral point to ground voltage is very low, and when one phase is disconnected, the neutral point to ground voltage rises; When the line voltage is normal, the three-phase voltage exists at the same time. When any phase is disconnected, the corresponding voltage disappears. The changing voltage can make the interlock protection device operate.
Using the current change, the corresponding phase current is zero when running according to the missing items, so that the current relay connected in series in the three-phase power supply is released, and the contactor loses power and disconnects the main power supply.
The characteristic of single operation interlock protection device using neutral point voltage change is that it uses fewer components, but requires high sensitivity. The reliability of single-phase interlocking protection device using line voltage change is higher than that of neutral point voltage change, but it uses more components. The sensitivity and reliability of single operation interlock protection device using current change are relatively high.