Issue:

The P3 relay does not show frequency readings during a real or virtual injection test.

Product:

PowerLogic™ P3 Relay

Environment:

Testing scenario using virtual or secondary voltage injection.

Cause:

The frequency is not measured if:

• The maximum of the three phase-to-phase or phase-to-neutral voltages is less than 5.5 × (VT primary / VT secondary) (primary voltage reference).
• The secondary voltage injection is less than 5.5 V.

This is a design condition to ensure accurate frequency measurement.

Resolution:

Increase the magnitude of the injected voltage during the virtual injection test. After raising the voltage above the required threshold, the frequency readings will appear as expected.

Released for: Schneider Electric UK