41
Checking the VT circuits Chapter 6
Checking the external optical and
electrical connections
2 Checking the VT circuits
Check that the wiring is in strict accordance with the supplied connection diagram.
Test the circuitry. The following tests are recommended:
• Polarity check.
• VT circuit voltage measurement (primary injection test).
• Earthing check.
• Phase relationship
• Insulation resistance check
The polarity check verifies the integrity of circuits and the phase relationships. The check should
be performed as close as possible to the IED.
The primary injection test verifies the VT ratio and the wiring all the way through from the pri-
mary 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.
Note!
Do not continue before any errors are corrected.
To Next Page
Loading...
