GE 489

GE Power Management
489 Generator Management Relay 4-31
4 SETPOINT PROGRAMMING 4.7 S6 VOLTAGE ELEMENTS
4
4.7.3 VOLTS/HERTZ
The Volts/Hertz elements may be used generator and unit transformer protection. They are active as soon as the magni-
tude and frequency of
V
ab
is measurable. The alarm element is definite time; the trip element can be definite time or a
curve. Once the V/Hz measurement
V
ab
exceeds the pickup level for the specified time, a trip or alarm will occur. The reset
rate is a linear reset time from the threshold of trip and should be set to match cooling characteristics of the protected
equipment. The measurement of V/Hz will be accurate through a frequency range of 5 to 90 Hz. Settings less than 1.00
only apply for special generators such as short circuit testing machines.

VOLTS/HERTZ

[ENTER] for more
VOLTS/HERTZ
ALARM: Off
Range: Off, Latched, Unlatched
ASSIGN ALARM
RELAYS (2-5): ---5
Range: Any combination of Relays 2 to 5
VOLTS/HERTZ ALARM
PICKUP: 1.00 x Nominal
Range: 0.50 to 1.99
×
Nominal in steps of 0.01
VOLTS/HERTZ ALARM
DELAY: 3.0 s
Range: 0.1 to 150.0 s in steps of 0.1
VOLTS/HERTZ ALARM
EVENTS: Off
Range: On, Off
VOLTS/HERTZ
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
VOLTS/HERTZ TRIP
PICKUP: 1.00 x Nominal
Range: 0.50 to 1.99
×
Rated in steps of 0.01
VOLTS/HERTZ TRIP
DELAY: 1.0 s
Range: 0.1 to 150.0 s in steps of 0.1
VOLTS/HERTZ CURVE
RESET RATE: 1.4 s
Range: 0.0 to 999.9 s in steps of 0.1
VOLTS/HERTZ TRIP
ELEMENT: Curve #1
Range: Curve #1, Curve #2, Curve #3, Definite Time
The formula for volts/hertz curve 1 is:
where:
T = trip time in seconds
D =
VOLTS/HERTZ TRIP DELAY
setpoint
V = RMS measurement of Vab
F = frequency of Vab
V
NOM
= generator voltage setpoint
F
S
= generator frequency setpoint
Pickup =
VOLTS/HERTZ TRIP PICKUP
setpoint
The V/Hz Curve 1 trip curves are shown on the right
for delay settings of 0.1, 0.3, 1, 3, and 10 seconds.
ENTER
ESCAPE
ð
ð
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
T
D
VF
⁄
V
nom
F
s
⁄()
Pickup
×
-----------------------------------------------------


2
1–
----------------------------------------------------------------------= , when
V
F
----
Pickup
>
0.01
0.1
1
10
100
1000
1.00 1.20 1.40 1.60 1.80 2.00
Multiples of Volts/Hertz Pickup
10
3
1
0.3
TIME DELAY SETTING
Time to Trip (seconds)
0.1