ABB REC670 Applications Manual page 240

Section 9
Voltage protection
234
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.
kn: 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 Un> up to Un> · (1.0 + CrvSatn/100) the used
voltage will be: Un> · (1.0 + CrvSatn/100). If the programmable curve is used, this
parameter must be calculated so that:
CrvSatn
× - >
B C 0
100
EQUATION1448 V1 EN-US
HystAbsn: Absolute hysteresis set in % of UBase. 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.
1MRK 511 401-UEN A
(Equation 93)
Bay control REC670 2.2 IEC
Application manual