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

7.3

Additional Functional Tests

7.3.1

Overload Curve Accuracy

Note
7–12
Courtesy of NationalSwitchgear.com
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.
In the
S2 SYSTEM SETUP
GENERATOR RATED MVA:
GENERATOR VOLTAGE PHASE-PHASE:
Note that setting
GENERATOR VOLTAGE PHASE-PHASE
FLA = 1000 A. For testing purposes ONLY!
In the
S2 SYSTEM SETUP
PHASE CT PRIMARY:
In the
S9 THERMAL MODEL
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:
In the
S9 THERMAL MODEL
THERMAL MODEL TRIP:
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 the
A2 METERING DATA
The thermal capacity used and estimated time to trip may be viewed in the
menu.
GENERATOR STATUS
Average Phase Pickup Level
Current
Displayed
1.05 × FLA
1050 A
1200 A 1.20 × FLA
1.75 × FLA
1750 A
3000 A 3.00 × FLA
6.00 × FLA
6000 A
10000 A 10.00 × FLA
FLA ---------------------------------------------------------------------------------------------------- -
=
3 ×
GEN. PARAMETERS
"1.04"
to "600" is equivalent to setting
CURRENT SENSING
"1000"
MODEL SETUP
"Standard"
"1.10 x FLA"
"0"
"1.00"
"No"
"Yes"
THERMAL ELEMENTS
"Latched" or "Unlatched"
CURRENT METERING
Expected Tolerance Range
Time to Trip
never n/a
795.44 s 779.53 to 811.35 s
169.66 s 166.27 to 173.05 s
43.73 s 42.86 to 44.60 s
9.99 s 9.79 to 10.19 s
5.55 s 5.44 to 5.66 s
Generator Rated MVA
Generator Phase-to-Phase Voltage
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 7: TESTING
menu, set:
"600"
menu, set:
menu, set:
"4"
menu, set:
menu.
A1 STATUS
Measured Time
to Trip (sec.)
(EQ 7.4)