Checking Ct Circuits; Checking Vt Circuits - ABB Relion 650 Series Commissioning Manual

1MRK 506 336-UEN B
4.7

Checking CT circuits

• Primary injection test to verify the current ratio of the CT, the correct wiring up to the
protection IED and correct phase sequence connection (that is L1, L2, L3.)
• CT secondary loop resistance measurement to confirm that the current transformer
secondary loop DC resistance is within specification and that there are no high resistance
joints in the CT winding or wiring.
• Earthing check of the individual CT secondary circuits to verify that each three-phase set
of main CTs is properly connected to the station earth and only at one electrical point.
• Insulation resistance check.
4.8

Checking VT circuits

Check that the wiring is in strict accordance with the supplied connection diagram.
Test the circuitry.
• 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 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.
Line distance protection REL650
Commissioning manual
See the engineering manual for information on how to create or modify an
application configuration and how to write to the IED.
Check that the wiring is in strict accordance with the supplied connection
diagram.
CT and VT connectors are pre-coded, and the CT and VT connector markings
are different. For more information, see the installation manual.
Both the primary and the secondary sides must be disconnected from the line
and the IED when plotting the excitation characteristics.
Correct possible errors before continuing to test the circuitry.
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Section 4
Starting up
M12182-2 v13
M11724-2 v8
35