ABB Relion 670 Series Applications Manual page 211

1MRK 511 401-UEN Rev. K
current may drop below the generator rated current after 0.5...1 s. Also, for generators with an
excitation system not fed from the generator terminals, a fault can occur when the automatic
voltage regulator is out of service. In such cases, to ensure tripping under such conditions,
overcurrent protection with undervoltage seal-in can be used.
To apply the VRPVOC function, the configuration is done according to figure 99. As seen in the
figure, the pickup of the overcurrent stage will enable the undervoltage stage. Once enabled,
the undervoltage stage will start a timer, which causes function tripping, if the voltage does
not recover above the set value. To ensure a proper reset, the function is blocked two seconds
after the trip signal is issued.
IEC12000183 V1 EN-US
Figure 99: Undervoltage seal-in of current start
8.16.3 Setting guidelines
Common base IED values for the primary current (
power (
GlobalBaseSel : Selects the global base value group used by the function to define IBase , UBase
SBase . Note that this function will only use IBase value.
and
8.16.3.1 Explanation of the setting parameters
Operation : Set to On in order to activate the function; set to Off to switch off the complete
function.
StartCurr : Operation phase current level given in % of IBase .
Characterist : Selection of time characteristic: Definite time delay and different types of inverse
time characteristics are available; see Technical Manual for details.
tDef_OC : Definite time delay. It is used if definite time characteristic is chosen; it shall be set
0 s if the inverse time characteristic is chosen and no additional delay shall be added. Note
to
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.
Bay control REC670
Application manual
I3P*
U3P*
OR
BLOCK
BLKOC
OR
BLKUV
SBase ) are set in global base values for settings function GBASVAL.
© Copyright 2017 Hitachi Power Grids. All rights reserved
VRPVOC
TRIP
TROC
TRUV
START
STOC
STUV
IBase ), primary voltage ( UBase ) and primary
Section 8
Current protection
Trip output
t
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