GE 489 - Manual (Page 85)

GE Multilin 489 Generator Management Relay 4-35
4 SETPOINTS 4.7 S6 VOLTAGE ELEMENTS
4
4.7.3 VOLTS/HERTZ
PATH: SETPOINTS ÖØ S6 VOLTAGE ELEMENTS ÖØ 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
р
р
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
T
D
V F ⁄
V
nom
F
s
⁄ ( ) Pickup ×
-----------------------------------------------------
⎝ ⎠
⎛ ⎞ 2
1 –
---------------------------------------------------------------------- = , when
V
F
---- Pickup >
808743A1-X1.CDR
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
T
IM
E
D
E
LA
Y
S
E
TT
IN
G
T
im
et
oT
ri
p
(s
e
c
ond
s)
0.1