ABB Relion 670 Series Applications Manual page 218

Section 8
Voltage protection
Pickupn : Set operate overvoltage operation value for step n , given as % of residual voltage
corresponding to
( )
>
V %
ANSIEQUATION2290 V1 EN-US
The setting is dependent of the required sensitivity of the protection and the system grounding. In
non-effectively grounded systems the residual voltage can be maximum the rated phase-to-
ground voltage, which should correspond to 100%.
In effectively grounded systems this value is dependent of the ratio Z0/Z1. The required setting to
detect high resistive ground faults must be based on network calculations.
tn : time delay of step n , given in s. The setting is highly dependent of the protection application. In
many applications, the protection function has the task 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 : Set reset type curve for step n . This parameter 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 for step n , to set to create programmable
undervoltage inverse time characteristic. Description of this can be found in the technical
reference manual.
CrvSatn : Set tuning parameter for step n . 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
In the voltage interval
CrvSatn /100). If the programmable curve is used this parameter must be calculated so that:
· (1.0 +
CrvSatn
×
B
100
EQUATION1448 V1 EN-US
HystAbsn: Absolute hysteresis for step n , set in % of VBase . The setting of this parameter is highly
dependent of the application.
212
VBase :
( )
×
VBase kV 3
Pickup> up to Pickup> · (1.0 + CrvSatn /100) the used voltage will be: Pickup>
- >
C 0
t1Min longer than the operation time for other
CrvSatn is set to compensate for this phenomenon.
1MRK 511 358-UUS A
(Equation 98)
(Equation 99)
Application manual