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.
PickUp_V
olt: Operation phase-to-phase voltage level given in % of VBase 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 VBase. 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 pickup level of the overcurrent stage given in % of
Pickup_Curr when the voltage is lower than 25% of VBase; so it defines the first point
of the characteristic (VDepFact*Pickup_Curr/100*IBase ; 0.25*VBase).
Step mode: it is the pickup level of the overcurrent stage given in % of Pickup_Curr
when the voltage is lower than VHighLimit/100*VBase.
VHighLimit: when the measured phase-to-phase voltage is higher than VHighLimit/
100*VBase, than the pickup level of the overcurrent stage is Pickup_Curr/100*IBase.
In particular, in Slope mode it define the second point of the characteristic
(Pickup_Curr/100*IBase ; VHighLimit/100*VBase).
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 (51V) 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:
1MRK 502 071-UUS A Section 9
Current protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 429
Application manual
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