Overexcitation Alarm - ABB REG650 Technical Manual

Section 9
Voltage protection
9.4.7.5
9.4.7.6
280
at low degrees of overexcitation, the very long delay is limited by 30 minutes, then the
TRIP output signal of OEXPVPH (24) will be set to 1 and TMTOTRIP will reach 0
seconds before THERMSTA reaches 100%.

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 abnormal voltages warning.
Logic diagram
BLOCK
V3P
Calculation
Ei
of internal M=
induced (Ei / f)
voltage Ei
(Vn / fn)
ANSI09000161 V4 EN
Figure 128: 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.
AlarmPickup
t>tAlarm
0-tAlarm
0
M>Pickup1
0-tMin
0
Pickup1
TD
M
M
TDForIEEE
0-1800s
0
M>Pickup2
Pickup2
M = relative Pickup as service value
1MRK 502 043-UUS B
ALARM
AND
TRIP
t>tMin
AND
³1
ANSI09000161-4-en.vsd
Technical Manual