Micom P631, Technical Manual

Page: 121 / 638

3.12.2 Phase Reversal Function
The phase reversal function is intended to protect machines in pumped storage
power stations that are operated either as motors or as generators, depending
on the demand. In such applications it is common practice to swap two phases in
order to facilitate the pumping operation. Because of this, the P631 phase
reversal function can maintain correct operation of all protection functions even
if phase reversal is carried out within the protected zone.
The processing is done right after A/D conversion, such that the link between
physical transformer input and internal numerical signal will be swapped,
depending on the setting. (The measured values stored in the respective
measured value memories are swapped.) Thus all further processing of
measured values and protection functions remains unchanged.
Phase reversal can be set independently for each transformer end and in each
parameter subset. The parameters are included in function group MAIN because
phase reversal affects not only the differential protection function (DIFF), but also
the negative sequence elements of Inverse and Definite Time Overcurrent
protection functions (IDMTx, DTOCx) as well as Current Transformer Supervision
(CTS) and Measuring- Circuit Monitoring (MCM_x) functions.
PS1 PS2 PS3 PS4 Description Range of Values
010 200 010 201 010 202 010 203 MAIN: Phase reversal a PSx
●
No swap (default)
●
A-B swapped
●
B-C swapped
●
C-A swapped
010 204 010 205 010 206 010 207 MAIN: Phase reversal b PSx
Using parameter subsets readily allows phase reversal to be activated via any
control interface (LOC, PC, COMMx) or via appropriately configured binary signal
inputs.
Since the currently active parameter subset is shown on the LC-display and may
be recalled from the recordings, phase reversal information is accessible. There
are however applications where an additional display of a phase reversal may be
useful. Such would be the case when recordings by a P631 are to be compared
with those by other devices not featuring phase reversal (e.g. Backup
overcurrent-time protection device) and without knowledge of the P631 setting
file. For this the following display is used:
Description Range of Values
036 220 MAIN: Phase reversal activ
●
No (default)
●
Yes
Phase reversal is active ( Yes ) when at least one of the setting parameters in the
active parameter subset has a value other than No swap .
The setting file must be viewed to determine which phases are swapped.
3 Operation
P631
P631/EN M/R-11-C // P631-310-650 3-65