GE Multilin 489 Instruction Manual page 162

Note
5–52
Courtesy of NationalSwitchgear.com
where T = trip time in seconds
D =
NEUTRAL OVERVOLTAGE TRIP DELAY
V = neutral voltage
V =
NEUTRAL O/V TRIP LEVEL
pickup
The neutral overvoltage curves are shown below. Refer to Appendix B for Application
Notes.
1000
100
10
1
0.1
1 1.1
FIGURE 5–8: Neutral Overvoltage Curves
GROUNDING SWITCH
59G
TO Vneutral OF EACH 489
FIGURE 5–9: Neutral Overvoltage Detection
If the ground directional element is enabled, the Neutral Overvoltage element should be
coordinated with it. In cases of paralleled generator grounds through the same point, with
individual ground switches, per sketch below, it is recommended to use a ground switch
status function to prevent maloperation of the element.
setpoint
setpoint
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Multiples of Overvoltage Pickup
AUXILIARY CONTACT
TO DIGITAL INPUT FOR
NEUTRAL O/V SUPERVISION
C(B)
B(C)
GENERATOR 1
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
10
3
1
0.3
0.1
1.9 2
808741A1.CDR
C(B)
A
A
B(C)
GENERATOR 2
808816A3.CDR