Negative Sequence Currenta - GE Multilin 489 Instruction Manual

7.2.4 Neutral Voltage (Fundamental) Accuracy
7.2.5 Negative Sequence Current Accuracy
7–6
Courtesy of NationalSwitchgear.com
The specification for neutral voltage (fundamental) accuracy is ±0.5% of full scale (100 V).
Perform the steps below to verify accuracy.
In the
S2 SYSTEM SETUP
NEUTRAL VOLTAGE TRANSFORMER:
NEUTRAL V.T. RATIO:
In the
S2 SYSTEM SETUP
GENERATOR NOMINAL FREQUENCY:
Measured values should be ±5.0 V.
Apply the voltage values shown in the table and verify accuracy of the
measured values.
View the measured values in the
METERING
Applied Neutral Voltage
at 60 Hz
10 V
30 V
50 V
The 489 measures negative sequence current as a percent of Full Load Amperes (FLA). A
sample calculation of negative sequence current is shown below. Given the following
generator parameters:
Rated MVA (P ) = 1.04
A
Voltage Phase to Phase (V
We have:
FLA
--------------------- -
=
3
With the following output currents:
I 780 0°, I ∠
=
a b
The negative-sequence current Ins is calculated as:
VOLTAGE SENSING
"10.00:1"
GEN. PARAMETERS
A2 METERING DATA
menu.
Expected Neutral Voltage
100 V
300 V
500 V
): 600 V
pp
6
P
1.04 × 10
A
1000 A
------------------------- -
= =
× ×
V 3 600
pp
1000 113° lag, I ∠ 1000 247° lag
= =
c
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 7: TESTING
menu, set:
"Yes"
menu, set:
"60 Hz"
VOLTAGE
Measured Neutral
Voltage
(EQ 7.1)
∠
(EQ 7.2)