ABB Relion 670 Series Applications Manual page 213

1MRK 511 358-UUS A
OpModen : This parameter describes how many of the three measured voltages that should be
above the set level to give operation. The setting can be
applications it is sufficient that one phase voltage is high to give operation. If the function shall be
insensitive for single phase-to-ground faults
normally rise in the non-faulted phases at single phase-to-ground faults. In subtransmission and
transmission networks the UV function is mainly a system supervision function and 3 out of 3 is
selected.
Pickupn : Set operate 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
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> ·
CrvSatn /100) the used voltage will be: Pickup> · (1.0 + CrvSatn /100). If the programmable
(1.0 +
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.
Application manual
- >
C 0
1 out of 3 , 2 out of 3 , 3 out of 3 . In most
1 out of 3 can be chosen, because the voltage will
t1Min longer than the operation time for other
Section 8
Voltage protection
(Equation 97)
207