GE 745 - 7.2.2 Dielectric Strength Testing

7–6 745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
PRELIMINARY WORK CHAPTER 7: COMMISSIONING
7.2.2 Dielectric Strength Testing
The 745 is rated for 2.2 kV AC for 1 second or 2.0 kV for 1 minute (as per IEC 60255-5)
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 filtering 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. Disconnect 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.
FIGURE 7–2: Testing for dielectric strength
GE Power Management
745
g
D1
AUXILIARY
LOGIC INPUT 1
OUTPUT CIRCUITS
CURRENT INPUTS
G2 1B
G1
H1
H2
1A
1A
1B
G2/3
F12
E12
G3
H3
1C
1C
G2/3
H10
G10
G1/2
G1/2
WINDING 1
H7
G7
3a
3a
H8
G8
H9
G9
3b
3b
3c
3c
H5 2b
G4
H4
G5
2a
2b
2a
H6
G6
2c
2c
WINDING 3WINDING 2
FILTER GND
SAFETY GND
CONTROL
POWER
H12
H11
G12
G11
B8
B9
TRIP
SOLID STATE
RTD
1
TRIP
TRIP
2
3
TRIP
4
5
E2
B12
B10
B11
+
E1
-
F1
E3
F2
E4
F3
E5
F4
E6
F5
COMMUNICATIONS
ANALOG OUTPUTS
LOGIC INPUT 9
LOGIC INPUT 10
LOGIC INPUT 11
LOGIC INPUT 12
LOGIC INPUT 13
LOGIC INPUT 7
LOGIC INPUT 6
LOGIC INPUT 5
LOGIC INPUT 4
LOGIC INPUT 3
LOGIC INPUT 2
LOGIC POWER OUT (COM)
LOGIC POWER OUT (+)
ACCESS
SETPOINT
LOGIC INPUT 8
D9
D5
D4
D3
D2
D7
D6
D8
+
D10
D11
D12
C1
-
C2
C3
C4
C5
+x
T
B4
LOGIC INPUT 14
LOGIC INPUT 15
LOGIC INPUT 16
RESERVED
RS422Tx
VT COM
RESERVED
RS422/485
C6
C7
C8
C9
C10
C11
C12
VT
RS485
E485
-
-
T
x
+
B7 B6 B5
A1+
485
COM
+
B2 B3
B1
ANALOG
INPUTS
-
+
-
COM
A2 A3
A4
A5
PROGRAMMING PORT
FRONT PANEL LOCAL
DEDICATED
INPUT
AUXILIARY
AUXILIARY
INPUTS
LOGIC
7
6
8
SELF-TEST
INPUTS
LOGIC
F10
E7
F6
E8
F7
E10
F9
E9
F8
F11
E11
SPARE
INPUT
VT
5+ A10
1+
2+ 3+ 4+
A6 A7 A8
A9
A127+
6+ A11
IRIG-B -
IRIG-B +
*
*
HIPOT TEST AT: 2.2KV AC FOR 1 SEC OR 2.0KV AC FOR 1 MINUTE AS PER IEC 60255-5
DO NOT HIPOT TEST
REMOVE FILTER GROUND (G11) DURING TEST
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
BLACKRED
DIELECTRIC STRENGTH TESTER
HV ON
VOLTAGE ADJUST
kV
RESET
FAULT
POWER
OFF
ON
LINE FAULT
814716A4.DWG
!