PWRA 220A

The WRA series Phase Control Relay monitors the sequence loss or reversal of 3-phase power supplies. The output relay is energized when the phase sequence is correct and is de-energize when the phase sequence is wrong or one phase is lost. It monitors the symmetry of 3 voltages and a loss of phase even when the voltage is re-injected through a machine. The rate of asymmetry is controlled between 5 and 15% by a top mounted potentiometer.

• LED relay status indicator
• Loss of any phase even if induced voltage reaches 95% of nominal voltage
• SPDT 10A relay output

Applications

Industrial, Power Management

Notes

The alarm threshold adjustment is 5 to 15% of asymmetry between the phases. The initial response time is 0.1 seconds at 5% asymmetry and 1 second at 15% after input power is applied.