The following chart includes the values generated for a three-phase balanced offline-meter test into an SEL-351 relay using a Megger Test-Set or RTS.

Test-Set
Relay Magnitude Angle
Voltage Channel V1 VA 69.28V 0°
Voltage Channel V2 VB 69.28V 120°
Voltage Channel V3 VC 69.28V 240°
Current Channel I1 IA 1.000A 0°
Current Channel I2 IB 1.000A 120°
Current Channel I3 IC 1.000A 240°

The relay is connected to 300:5 CTs and 35:1 PTs. Is everything correct in the following meter test?

Here’s what we know so far:

• The metering results aren’t zero, which means the relay’s analog to digital converters are working.
• The CT and PT ratio settings in the relay are correct (notice that we don’t need to look at the actual settings to determine this). We’re injecting 1A in all three phases and the relay is reporting approximately 60A. The worst-case accuracy is -0.355% error, which is consistent with the 60:1 CT ratio. The relay is reporting approximately 2.42kV in all three-phases with a maximum percent error of -.07%, which matches the PT ratio.
  • The relay is looking in the correct direction because the currents and voltages are in-phase.
  • We are injecting A-B-C, or 1-2-3, rotation because the following pattern exists in the relay and test-set: A-Phase is 0°, B-Phase lags A-Phase by 120°, and C-Phase lags A-Phase by 240°.
  • The relay is programmed with the WRONG phase rotation because the sequence components show 0% positive sequence, 100% negative sequence, and 0% zero-sequence.