ABB RELION REX640, Техническое руководство, Страница: 1721 / 1960

Command error
OL5ATCC supervises the tap changer position information of the own transformer
when a control pulse is given. If the correct position change (direction depends on
the comparison of the settings
Raise block tap and Lower block tap) is not seen by
OL5ATCC in
Cmd error delay time after the pulse start, the alarm is issued.
If the position information is not connected, no alarm is generated. The alarm is
reset when the correct change in position value is detected after a given pulse or if a
new command pulse is given.
The monitored data ALARM_REAS is set during an alarm. This means that if the
alarm reason is active, ALARM_REAS has the value "Cmd error".
TCO signal fails
If the tap changer operating signal
TCO
stays active for more than 15 seconds after
the output pulse deactivation, OL5ATCC sees this as an abnormal condition and
assumes that the tap changer is stuck. The alarm is reset when the
TCO
input signal
deactivates. The monitored data ALARM_REAS is set during the alarm. This means
that only if the alarm reason is active, ALARM_REAS has the value "TCO error".
If the
TCO
input signal is not connected (indicated by bad quality), this type of alarm
is not possible.
Regulator pumping
Faulty settings may cause the regulator to give control pulses too frequently. For
example, too low a setting for the
Band width voltage ( Figure 916
) can result
in a pumping condition where the regulator has problems to bring the regulated
voltage to a desired level. To detect this, OL5ATCC has a setting
Max operations
in 1h, which defines the allowed number of lowering and raising commands during
a one-hour sliding time window. The detection is active both in the manual and
automatic operation modes. The alarm is reset after the counted number of the
operations during the one-hour time window is less than the set value. The number
of executed operations per last one hour can be read from the monitored data
OP_TM_NUM_H. However, this parameter is updated only in three-minute intervals.
Again, the monitored data ALARM_REAS is set during an alarm. This means that only
if alarm reason is active, ALARM_REAS has the value "Pump error".
The operation of OL5ATCC is not blocked during an alarm situation, but all the
alarms mentioned above cause the automatic operation to be delayed, which means
that the set delay times T1 and T2 are doubled.
In addition to the alarm detections, OL5ATCC provides a nonvolatile operation
counter parameter (monitored data OPR_CNT) for determining the service intervals
of the tap changer. The counter gives the total number of raising and lowering
commands given in the manual and automatic modes. All commands, even those
that are omitted by the tap changer due to its operation sequence, are calculated in
a cumulative counter. This data parameter can be reset via the parameter
OL5ATCC
counter on the Clear menu.
9.10.6 Application
See the application manual for more information.
1MRS759142 F Control functions
REX640
Technical Manual
1721