ABB Relion 670 Series Applications Manual page 230

Section 8
Voltage protection
Pickupn: Set pickup overvoltage operation value for step n, given as % of VBase. The setting is highly
dependent of the protection application. Here it is essential to consider the maximum voltage at non-
faulted situations. Normally this voltage is less than 110% of nominal voltage.
tn: time delay of step n, given in s. The setting is highly dependent of the protection application. In many
applications the protection function is used to prevent damages to the protected object. The speed might
be important for example in case of protection of transformer that might be overexcited. The time delay
must be co-ordinated with other automated actions in the system.
tResetn: Reset time for step n if definite time delay is used, given in s. The default value is 25 ms.
tnMin: Minimum operation time for inverse time characteristic for step n, given in s. For very high
voltages the overvoltage function, using inverse time characteristic, can give very short operation time.
This might lead to unselective trip. By setting t1Min longer than the operation time for other protections
such unselective tripping can be avoided.
ResetTypeCrvn: This parameter for inverse time characteristic can be set: Instantaneous, Frozen time,
Linearly decreased. The default setting is Instantaneous.
tIResetn: Reset time for step n if inverse time delay is used, given in s. The default value is 25 ms.
TDn: Time multiplier for inverse time characteristic. This parameter is used for co-ordination between
different inverse time delayed undervoltage protections.
ACrvn, BCrvn, CCrvn, DCrvn, PCrvn: Parameters to set to create programmable under voltage inverse
time characteristic. Description of this can be found in the technical reference manual.
CrvSatn: When the denominator in the expression of the programmable curve is equal to zero the time
delay will be infinity. There will be an undesired discontinuity. Therefore a tuning parameter CrvSatn is set
to compensate for this phenomenon. In the voltage interval Pickup> up to Pickup> · (1.0 + CrvSatn/100)
the used voltage will be: Pickup> · (1.0 + CrvSatn/100). If the programmable curve is used, this
parameter must be calculated so that:
CrvSatn
×
B
100
EQUATION1448 V1 EN-US
HystAbsn: Absolute hysteresis set in % of VBase. The setting of this parameter is highly dependent of
the application. If the function is used as control for automatic switching of reactive compensation
devices the hysteresis must be set smaller than the voltage change after switching of the compensation
device.
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C 0
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1MRK 505 370-UUS Rev. K
(Equation 76)
Busbar protection REB670
Application manual