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Low Voltage Protection |
Low Voltage Disconnects - Protection device operates to disconnect the motor when the supply voltage drops below a preset value. The motor must be manually restarted upon resumption of normal supply voltage. |
Low Voltage Release - Protection device interrupts the circuit when the supply voltage drops below a preset value and re-establishes the circuit when the supply voltage returns to normal. |
Phase Failure Protection |
Interrupts the power in all phases of a three-phase circuit upon failure of any one phase. |
C Normal fusing and overload protection may not adequately protect a polyphase motor from |
damaging single phase operation. Without this protection, the motor will continue to operate if one phase is lost. |
C Large currents can be developed in the remaining stator circuits which eventually burn out. |
C Phase failure protection is the only effective way to protect a motor properly from single |
phasing. |
Phase Reversal Protection |
Used where running a motor backwards (opposite direction from normal) would cause operational or safety problems. |
C Most three phase motors will run the opposite direction by switching the connections of any |
two of the three phases. |
C The device interrupts the power to the motor upon detection of a phase reversal in the three- |
phase supply circuit. |
C This type of protection is used in applications like elevators where it would be damaging or |
dangerous for the motor to inadvertently run in reverse. |
Ground Fault Protection |
C Operates when one phase of a motor shorts to ground preventing high currents from |
damaging the stator windings and the iron core. |
Other Motor Protection Devices |
Bearing Temperature Monitors & Protection Winding Temperature Monitors & Protection Devices Current Differential Relays (Phase Unbalance) Vibration Monitors & Protection |