P54x/EN OP/La4 Operation
(OP) 5-132
MiCOM P543, P544, P545 & P546
OP
The CTRL. I/P LABELS column makes it possible to change the text associated with each
individual control input. This text will be displayed when a control input is accessed by the
hotkey menu, or it can be displayed in the PSL.
Note: With the exception of pulsed operation, the status of the control inputs
is stored in non volatile memory. In the event that the auxiliary supply
is interrupted the status of all the inputs will be recorded. Following
the restoration of the auxiliary supply the status of the control inputs,
prior to supply failure, will be reinstated. If the battery is missing or flat
the control inputs will set to logic 0 once the auxiliary supply is
restored.
3.7 Real time clock synchronization via opto-inputs
In modern protective sche
mes it is often desirable to synchronize the relays real time clock
so that events from different relays can be placed in chronological order. This can be done
using the IRIG-B input, if fitted, or via the communication interface connected to the
substation control system. In addition to these methods the MiCOM P54x range offers the
facility to synchronize via an opto-input by routing it in PSL to DDB 400 (Time Sync.).
Pulsing this input will result in the real time clock snapping to the nearest minute. The
recommended pulse duration is 20 ms to be repeated no more than once per minute. An
example of the time sync. function is shown.
Time of “Sync. Pulse” Corrected time
19:47:00 to 19:47:29 19:47:00
19:47:30 to 19:47:59 19:48:00
Note: The above assumes a time format of hh:mm:ss.
To avoid the event buffer from being filled with unnecessary time sync. events, it is possible
to ignore any event that is generated by the time sync. opto input. This can be done by
applying the following settings:
Menu Text Value
RECORD CONTROL
Opto Input Event Enabled
Protection Event Enabled
DDB 63 - 32 (Opto Inputs) Set “Time Sync.” associated opto to 0
To improve the recognition time of the time sync. opto input by approximately 10 ms, the
opto input filtering could be disabled. This is achieved by setting the appropriate bit to 0 in
the Opto Filter Cntl. cell (OPTO CONFIG. column). Disabling the filtering may make the
opto input more susceptible to induced noise. Fortunately the effects of induced noise can
be minimized by using the methods described in Firmware Design (P54x/EN FD) chapter.
3.8 Fault locator
The
relay has an integral fault locator that uses information from the current and voltage
inputs to provide a distance to fault location. The sampled data from the analog input circuits
is written to a cyclic buffer until a fault condition is detected. The data in the input buffer is
then held to allow the fault calculation to be made. When the fault calculation is complete
the fault location information is available in the relay fault record.
When applied to parallel circuits mutual flux coupling can alter the impedance seen by the
fault locator. The coupling will contain positive, negative and zero sequence components. In
practice the positive and negative sequence coupling is insignificant. The effect on the fault
locator of the zero sequence mutual coupling can be eliminated by using the mutual
compensation feature provided.
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