ABB REC670 Applications Manual page 263

1MRK 511 401-UUS A
Bay control REC670 2.2 ANSI
Application manual
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.
For fuse supervision normally only this alarm level is used and a suitable voltage level
is 3-5% if the ratio correction factor has been properly evaluated during
commissioning.
For other applications it has to be decided case by case.
tAlarm: The time delay for alarm is set by this parameter. Normally, few seconds delay
can be used on capacitor banks alarm. For fuse failure supervision (SDDRFUF) the
alarm delay can be set to zero.
Section 9
Voltage protection
257