Monitoring of rotation direction / phase sequence and phase failure

Phase monitoring consists of checking for a few seconds after compressor start whether all phases are activated in the correct order and according to the specified voltage. This ensures the correct rotation direction and completeness of the magnetic rotating field at the motor connection. If a wrong rotation direction is detected, the protection device locks out immediately.

In the compressor's state of delivery, this protection function is fully wired and connected to the compressor protection device.

In case of phase failure, the compressor will be shut off. The protection device will lock out only if the error occurs repeatedly; see also device description.

Phase monitoring is delayed by a few seconds on compressor protection devices that are suitable for soft starters and frequency inverters. The time it takes for the voltage at the motor terminals to enter the detection range of the compressor protection device must be significantly shorter than this delay.