3 Phase motors need the power supply to be present in all the 3 supply phases. Failing of any one of the phases is termed as single phasing. During single phasing, the motors draw more current than the rated value which results in burning of the motor coils.

Single Phase Preventor is a product which provides a solution to this problem by sensing the single phase condition and instantaneously turning OFF the power supply to the motor. Single Phase preventors are mandatorily used in the majority of 3 Phase motor starters.

Current Sensing Type:

The Current sensing type single phase preventors allow the motor load to flow through them. They sense the current drawn by the motor in all 3 lines constantly. The motor is instantaneously turned OFF as soon as the current drawn in any one of the lines is 0. Current sensing preventors sense the loss of a load current in both the load end and the supply end offering dual protection against single phasing.

Voltage Sensing Type - PFR Series:

The Voltage sensing type single phase preventors sense the incoming 3 Phase power supply constantly. The motor is instantaneously turned OFF as soon as the power supply in any one of the supply lines is absent. The voltage sensing Preventors also make sure that the motor is not turned ON in the absence of any one the supply lines. They also allow the motor to operate only in one particular supply sequence there by not allowing the motor to run in the reverse direction.

Single Phase Preventor

Auto with Single Phase Preventors