ABB REG670 Applications Manual page 424

Section 10
Voltage protection
418
of the protection of a 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: 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.
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 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 infinite. There will be
an undesired discontinuity. Therefore, a tuning parameter CrvSatn is set to
compensate for this phenomenon. In the voltage interval U> up to U> · (1.0 +
CrvSatn/100) the used voltage will be: U> · (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
HystAbsn: Absolute hysteresis for step n, set in % of UBase. The setting of this
parameter is highly dependent of the application. The hysteresis is used to avoid
oscillations of the START output signal. This signal resets when the measured voltage
drops below the setting level and leaves the hysteresis area. Make sure that the set
value for parameter HystABSn is somewhat smaller than the set pickup value.
Otherwise there is a risk that step n will not reset properly.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1MRK 502 071-UEN -
(Equation 248)
Application manual