ABB REB670 Applications Manual page 252

Section 8
Voltage protection
246
Operation: Off/On
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
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 · RFLx and shall be equal to the V1 voltage. 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 number of elements per phase in series and parallel. Normally values required are
given by capacitor bank supplier.
1MRK 505 337-UUS -
Application manual