Overexcitation Alarm - ABB Relion Technical Manual

Section 9
Voltage protection
9.4.7.5
9.4.7.6
9.4.8
308

Overexcitation alarm

A separate step, AlarmPickup, is provided for alarming purpose. It is normally set 2%
lower than (Pickup1) and has a definite time delay, tAlarm. This will give the operator an
early warning.
Logic diagram
BLOCK
V3P
Calc ulation
Ei
of inte rnal M=
induced (Ei / f)
voltage Ei
(Vn / fn)
ANSI09000161 V5 EN
Figure 141: A simplified logic diagram of the Overexcitation protection OEXPVPH
(24)
Simplification of the diagram is in the way the IEEE delays are calculated. The cooling
process is not shown. It is not shown that voltage and frequency are separately checked
against their respective limit values.
Technical data
Table 177: OEXPVPH (24) technical data
Function
Trip value, pickup
Trip value, alarm
Trip value, high level
Table continues on next page
AlarmPickup
t>tAlarm
0-tAlarm
0
M>Pickup1
0-tMin
0
Pick up1
TD
M
M
TDForIEEE
0-1800s
0
M>Pick up2
Pick up2
M = relative Pickup as service value
Range or value
VBase /f
(100–180)% of ( )
n
(50–120)% of pickup level
VBase /f
(100–200)% of ( )
n
1MRK 502 048-UUS A
ALARM
AND
100 ms
t>tMin TRIP
AND
1
ANSI09000161-5-en.vsd
Accuracy
± 0.5% of V
± 0.5% of V at V ≤ V
n
± 0.5% of V at V > V
± 0.5% of V
Technical manual
n
n