GE 489 - Manual (Page 86)

4-36 489 Generator Management Relay GE Multilin
4.7 S6 VOLTAGE ELEMENTS 4 SETPOINTS
4
Volts/Hertz is calculated per unit as follows:
4.7.4 PHASE REVERSAL
PATH: SETPOINTS ÖØ S6 VOLTAGE ELEMENTS ÖØ PHASE REVERSAL
The 489 can detect the phase rotation of the three phase voltages. A trip will occur within 200 ms if the Phase Reversal fea-
ture is turned on, the generator is offline, each of the phase-phase voltages is greater than 50% of the generator rated
phase-phase voltage and the phase rotation is not the same as the setpoint. Loss of VT fuses cannot be detected when the
generator is offline and could lead to maloperation of this element. If the VT type is selected as "None", the phase reversal
protection is disabled.
The formula for Volts/Hertz Curve 2 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 2 trip curves are shown on the right
for delay settings of 0.1, 0.3, 1, 3, and 10 seconds.
The formula for Volts/Hertz Curve 3 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 3 trip curves are shown on the right
for delay settings of 0.1, 0.3, 1, 3, and 10 seconds.
„ PHASE REVERSAL
„ [ENTER] for more PHASE REVERSAL
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
T
D
V F ⁄
V
nom
F
s
⁄ ( ) Pickup ×
----------------------------------------------------- 1 –
-------------------------------------------------------------- = , when
V
F
---- Pickup >
808743A1-X2.CDR
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
0.1
T
im
et
oT
ri
p
(s
e
c
ond
s)
T
D
V F ⁄
V
nom
F
s
⁄ ( ) Pickup ×
-----------------------------------------------------
⎝ ⎠
⎛ ⎞ 0.5
1 –
-------------------------------------------------------------------------- = , when
V
F
---- Pickup >
808743A1-X3.CDR
0.1
1
10
100
1000
10000
1.00 1.20 1.40 1.60 1.80 2.00
Multiples of Voltz/Hertz Pickup
10
3
1
0.3
T
IM
E
D
E
LA
Y
S
E
TT
IN
G
0.1
T
im
et
oT
ri
p
(s
e
c
ond
s)
NOTE
Volts/Hertz
phase-phase voltage rated phase-phase voltage ⁄
frequency rated frequency ⁄
---------------------------------------------------------------------------------------------------------------------------------- =
ENTER
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р
р
MESSAGE
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