ABB RELION 670 Series Applications Manual page 220

Section 8
Voltage protection
VDCPTOV (60) function has a block input (BLOCK) where a fuse failure supervision (or MCB
tripped) can be connected to prevent problems if one fuse in the capacitor bank voltage
transformer set has opened and not the other (capacitor voltage is connected to input V2). It will
also ensure that a fuse failure alarm is given instead of a Undervoltage or Differential voltage
alarm and/or tripping.
8.4.3 Setting guidelines
The parameters for the voltage differential function are set via the local HMI or PCM600.
The following settings are done for the voltage differential function.
Operation : Off / On
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ), ( VBase )
SBase ).
and (
BlkDiffAtVLow : The setting is to block the function when the voltages in the phases are low.
RFLx : Is the setting of the voltage ratio compensation factor where possible differences between
the voltages is compensated for. The differences can be due to different voltage transformer
ratios, different voltage levels e.g. the voltage measurement inside the capacitor bank can have a
different voltage level but the difference can also e.g. be used by voltage drop in the secondary
circuits. The setting is normally done at site by evaluating the differential voltage achieved as a
service value for each phase. The factor is defined as V2 ·
Each phase has its own ratio factor.
VDTrip : The voltage differential level required for tripping is set with this parameter. For
application on capacitor banks the setting will depend of the capacitor bank voltage and the
number of elements per phase in series and parallel. Capacitor banks must be tripped before
excessive voltage occurs on the healthy capacitor elements. The setting values required are
normally given by the capacitor bank supplier. For other applications it has to be decided case by
case. For fuse supervision normally only the alarm level is used.
tTrip : The time delay for tripping is set by this parameter. Normally, the delay does not need to be
so short in capacitor bank applications as there is no fault requiring urgent tripping.
tReset : The time delay for reset of tripping level element is set by this parameter. Normally, it can
be set to a short delay as faults are permanent when they occur.
For the advanced users following parameters are also available for setting. Default values are here
expected to be acceptable.
V1Low : The setting of the undervoltage level for the first voltage input is decided by this
parameter. The proposed default setting is 70%.
V2Low : The setting of the undervoltage level for the second voltage input is decided by this
parameter. The proposed default setting is 70%.
tBlock : The time delay for blocking of the function at detected undervoltages is set by this
parameter.
VDAlarm : The voltage differential level required for alarm is set with this parameter. For
application on capacitor banks the setting will depend of the capacitor bank voltage and the
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RFLx and shall be equal to the V1 voltage.
1MRK 505 337-UUS A
SEMOD153915-5 v3
Application manual