ABB REL670 2.2 IEC - Voltage-Restrained Overcurrent Protection for Generator and Step-Up Transformer

shall be added. Note that the value set is the time between activation of the start
and the trip outputs.
k: Time multiplier for inverse time delay.
tMin: Minimum operation time for all inverse time characteristics. At high currents
the inverse time characteristic might give a very short operation time. By setting
this parameter the operation time of the step can never be shorter than the setting.
Operation_UV: it sets On/Off the operation of the under-voltage stage.
StartVolt: Operation phase-to-phase voltage level given in % of UBase for the
under-voltage stage. Typical setting may be, for example, in the range from 70% to
80% of the rated voltage of the generator.
tDef_UV: Definite time delay. Since it is related to a backup protection function, a
long time delay (for example 0.5 s or more) is typically used. Note that the value
set is the time between activation of the start and the trip outputs.
EnBlkLowV: This parameter enables the internal block of the undervoltage stage
for low voltage condition; the voltage level is defined by the parameter
BlkLowVolt.
BlkLowVolt: Voltage level under which the internal blocking of the undervoltage
stage is activated; it is set in % of UBase. This setting must be lower than the
setting StartVolt. The setting can be very low, for example, lower than 10%.
VDepMode: Selection of the characteristic of the start level of the overcurrent stage
as a function of the phase-to-phase voltage; two options are available: Slope and
Step. See Technical Manual for details about the characteristics.
VDepFact: Slope mode: it is the start level of the overcurrent stage given in % of
StartCurr when the voltage is lower than 25% of UBase; so it defines the first point
of the characteristic (VDepFact*StartCurr/100*IBase ; 0.25*UBase). Step mode: it
is the start level of the overcurrent stage given in % of StartCurr when the voltage
is lower than UHighLimit/100*UBase.
UHighLimit: when the measured phase-to-phase voltage is higher than
UHighLimit/100*UBase, than the start level of the overcurrent stage is StartCurr/
100*IBase. In particular, in Slope mode it define the second point of the
characteristic (StartCurr/100*IBase ; UHighLimit/100*UBase).
9.14.3.2 Voltage-restrained overcurrent protection for generator and step-up
transformer
GUID-263B960B-2280-461C-B455-F17B7D278F60 v8
An example of how to use VRPVOC function to provide voltage restrained
overcurrent protection for a generator is given below. Let us assume that the time
coordination study gives the following required settings:
Section 9 1MRK 506 369-UEN B
Current protection
530 Line distance protection REL670 2.2 IEC
Application manual