ABB RELION 670 SERIES Applications Manual page 595

1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual
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.
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 10
Voltage protection
589