Dielectric Strength Testing - GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual

8 COMMISSIONING 8.2 PRELIMINARY WORK

8.2.2 DIELECTRIC STRENGTH TESTING

The 745 is rated for 2000 V DC isolation between relay contacts, CT inputs, VT inputs and the safety ground terminal G12.
Some precautions are required to prevent 745 damage during these tests.
Filter networks and transient protection clamps are used between control power and the filter ground terminal G11. This fil-
tering is intended to filter out high voltage transients, radio frequency interference (RFI), and electromagnetic interference
(EMI). The filter capacitors and transient suppressors could be damaged by application continuous high voltage. Discon-
nect filter ground terminal G11 during testing of control power and trip coil supervision. CT inputs, VT inputs, and output
relays do not require any special precautions. Low voltage inputs (< 30 V) such as RTDs, analog inputs, analog outputs,
digital inputs, and RS485 communication ports are not to be tested for dielectric strength under any circumstance.
GE Power Management
8
Figure 8–2: TESTING FOR DIELECTRIC STRENGTH
GE Multilin 745 Transformer Management Relay 8-5
Courtesy of NationalSwitchgear.com