Checking Vt Circuits; Checking The Rtxp Test Switch - ABB Relion 650 Series REL650 Commissioning Manual

Section 3
Starting up
3.8
3.9
32

Checking VT circuits

Check that the wiring is in strict accordance with the supplied connection diagram.
Correct possible errors before continuing to test the circuitry.
Test the circuitry.
• Polarity check
• VT circuit voltage measurement (primary injection test)
• Grounding check
• Phase relationship
• Insulation resistance check
The polarity check verifies the integrity of circuits and the phase relationships. The
check must be performed as close to the IED as possible.
The primary injection test verifies the VT ratio and the wiring all the way from the
primary system to the IED. Injection must be performed for each phase-to-neutral
circuit and each phase-to-phase pair. In each case, voltages in all phases and neutral are
measured.

Checking the RTXP test switch

The RTXP test switch is designed to provide the means of safe testing of the IED. This
is achieved by the electromechanical design of the test switch and test plug handle.
When the test plug handle is inserted, it first blocks the trip and alarm circuits then it
short circuits the CT secondary circuit and opens the VT secondary circuits making the
IED available for secondary injection.
When pulled out, the test handle is mechanically stopped in half withdrawn position. In
this position, the current and voltage enter the protection, but the alarm and trip circuits
are still isolated. Before removing the test handle, check that no trip or alarms are
present in the IED.
Not until the test handle is completely removed, the trip and alarm circuits are restored
for operation.
1MRK 506 331-UUS A
Commissioning Manual