Additional Functional Tests; Overload Curve Accuracy - GE 489 Instruction Manual

7 TESTING

7.3ADDITIONAL FUNCTIONAL TESTS

The specification for overload curve timing accuracy is ±100 ms or ±2% of time to trip. Pickup accuracy is as per the current
inputs (±0.5% of 2 × CT when the injected current is less than 2 × CT and ±1% of 20 × CT when the injected current is equal
to or greater than 2 × CT). Perform the steps below to verify accuracy.
1. Alter the following setpoints:
S2 SYSTEM SETUP GEN. PARAMETERS
S2 SYSTEM SETUP GEN. PARAMETERS
(Note: This is equivalent to setting FLA = 1000 A – For testing purposes ONLY!)
S2 SYSTEM SETUP CURRENT SENSING
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL MODEL SETUP
S9 THERMAL MODEL THERMAL ELEMENTS
2. Any trip must be reset prior to each test. Short the emergency restart terminals momentarily immediately prior to each
overload curve test to ensure that the thermal capacity used is zero. Failure to do so will result in shorter trip times.
Inject the current of the proper amplitude to obtain the values as shown and verify the trip times. Motor load may be
viewed in:
A2 METERING DATA CURRENT METERING
3. Thermal capacity used and estimated time to trip may be viewed in:
A1 STATUS GENERATOR STATUS
AVERAGE PHASE PICKUP LEVEL
CURRENT DISPLAYED
1050 A
1200 A
1750 A
3000 A
6000 A
10000 A
Generator Rated MVA
FLA ---------------------------------------------------------------------------------------------------------- -
=
×
3 Generator Phase-to-Phase Voltage
NOTE
GE Multilin
GENERATOR RATED MVA:
GENERATOR VOLTAGE PHASE-PHASE:
PHASE CT PRIMARY:
SELECT CURVE STYLE:
OVERLOAD PICKUP LEVEL:
UNBALANCE BIAS K FACTOR:
HOT/COLD SAFE STALL RATIO:
ENABLE RTD BIASING:
STANDARD OVERLOAD CURVE NUMBER:
ENABLE THERMAL MODEL:
THERMAL MODEL TRIP:
EXPECTED TIME TO
TRIP
1.05 × FLA never
1.20 × FLA
795.44 sec.
1.75 × FLA
169.66 sec.
3.00 × FLA
43.73 sec.
6.00 × FLA 9.99 sec.
10.00 × FLA 5.55 sec.
489 Generator Management Relay
7.3 ADDITIONAL FUNCTIONAL TESTS

7.3.1 OVERLOAD CURVE ACCURACY

"1.04"
"600"
"1000"
"Standard"
"1.10 x FLA"
"0"
"1.00"
"No"
"4"
"Yes"
"Latched" or "Unlatched"
TOLERANCE RANGE
n/a
779.53 to 811.35 sec.
166.27 to 173.05 sec.
42.86 to 44.60 sec.
9.79 to 10.19 sec.
5.44 to 5.66 sec.
MEASURED TIME TO
TRIP (SEC.)
(EQ 7.4)
7-9
7