GE DGP Series, Instruction Manual

Page: 141 / 278

GE Power Management DGP Digital Generator Protection System 4-
37
4 ACCEPTANCE TESTS 4.7 PROTECTION TESTS
4
4.7.24 T27: VOLTAGE TRANSFORMER FUSE FAILURE VTFF
1. Make the following Settings changes:
DIG INP
(2501) SELBKDI1 = NO BLK (0)
VTFF
(2601) VTFF = DISABLE (0) – set for TEST mode only
2. Connect relay as shown in Figure 4–8: STANDARD FUNCTIONAL TEST CONNECTIONS on page 4–26.
3. Set up relay in test mode for the VTFF function; VTFF ON will be displayed on the MMI.
4. Set the voltage inputs to:
VA = 70 V rms
∠
0°,
VB = 70 V rms
∠
–120°,
VC = 70 V rms
∠
–240°.
5. Set the current inputs to:
IAS = 0.5 A rms
∠
90°,
IBS = 0.5 A rms
∠
–30°,
ICS = 0.5 A rms
∠
–150°.
6. Verify that neither the test pickup nor the test trip operates.
7. Decrease the voltage in all three phases to 49 V rms. Verify that test pickup and test trip operate in 12.4 to
13.0 seconds.
4.7.25 T28: TOC GROUND OVERCURRENT 51GN
Skip this test if your DGP model does not include this function. This function is not available
on DGP***AAA model relays.
1. Make the following Settings changes:
51GN
(2803) PICKUP = 0.5 (0.1)
(2804) TIME FAC = 1.0
2. Connect as shown in Figure 4–6: GENERATOR DIFFERENTIAL TEST CONNECTIONS on page 4–19.
3. Set up relay in test mode for the 51GN function; 51GN ON will be displayed on the MMI.
4. Set the current input to: IAR = 0.45 (0.09) A rms. Set the voltage inputs to:
VA = 70 V rms
∠
0°,
VB = 70 V rms
∠
–120°
,
VC = 70V rms
∠
–240°.
5. Verify that neither the test pickup nor the test trip operates.
6. Increase the current input to: IAR = 1.5 (0.3) A rms. Verify that test pickup operates immediately, and test
trip operates in 1.30 to 1.45 seconds.
7. Repeat steps 4 and 5, but use 20 (4.0) A rms in step 4, and verify that test pickup operates immediately
and test trip operates in 184 to 204 ms.
NOTE