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_Volt
: 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
Summary of Contents for RELION 670 SERIES REG670
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