GE DGP Series, Instruction Manual

Page: 156 / 278

5-
12
DGP Digital Generator Protection System GE Power Management
5.3 MEASURING UNIT TESTS 5 PERIODIC TESTS
5
5.3.10 T13: VOLTS/HERTZ OVEREXCITATION ALARM 24A
1. Record the following Settings:
24A
(1302) PICKUP (V/Hz Pickup) = ______
(1303) TL6 (V/Hz Time Delay) = ______ sec.
2. Volt/Hertz Overexcitation Alarm is calculated with the following relation:
equation 5–9
Actual V/Hz is the voltage applied to any one phase divided by the frequency applied. PICKUP is Setting
1302: PICKUP,
V
NOM
is defined by
equation 5–10
where NOM VOLT is the nominal voltage Setting 114: NOM VOLT, and x = 1.732 or 1, depending on Set-
ting 116: VTCONN (for WYE, x = 1.732; for DELTA, x = 1). SYSFREQ is Setting 102. If equation 5–9 is sat-
isfied, the test pickup relay will operate. If this condition persist for a time equal to TL-6, the test trip relay
will operate.
3. Connect relay as shown in Figure 4–8: STANDARD FUNCTIONAL TEST CONNECTIONS on page 4–26.
4. Set up relay in test mode for the 24A function; 24A ON will be displayed on the MMI.
5. Set all current inputs to 0. Set:
VA = 70 V rms
∠
0°
VB = 70 V rms
∠
–120°
VC = 70 V rms
∠
–240°
6. Change the voltage of any one phase until Voltage/Frequency is equal to: V/Hz s 0.1 = ______.
This will cause the test pickup relay to operate and the test trip relay will operate after the Trip Time has
expired.
7. Change the voltage of any one phase until Voltage/Frequency is equal to: V/Hz setting – 0.1 =______. The
test pickup and test trip relays will not operate.
Actual V/Hz
PICKUP V
NOM
×
SYSFREQ
-------------------------------------------- =
V
NOM
NOM VOLT
x
------------------------------- =