ABB RELION REB670, Applications Manual

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OpModen : This parameter describes how many of the three measured voltages should
be below the set level to give operation for step n. The setting can be 1 out of 3 , 2 out
of 3 or 3 out of 3 . In most applications, it is sufficient that one phase voltage is low to
give operation. If UV2PTUV (27) shall be insensitive for single phase-to-ground
faults,
2 out of 3 can be chosen. In subtransmission and transmission networks the
undervoltage function is mainly a system supervision function and 3 out of 3 is
selected.
Pickupn : Set pickup undervoltage operation value for step n , given as % of the
parameter VBase . The setting is highly dependent on the protection application. It is
essential to consider the minimum voltage at non-faulted situations. Normally, this
non-faulted voltage is larger than 90% of the nominal voltage.
tn : time delay of step n , given in s. This setting is dependent on the protection
application. In many applications the protection function shall not directly trip when
there is a short circuit or ground faults in the system. The time delay must be
coordinated to the other short circuit protections.
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.
When using inverse time characteristic for the undervoltage function during very low
voltages can give a short operation time. This might lead to unselective tripping. 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 to
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
coordination between different inverse time delayed undervoltage protections.
ACrvn , BCrvn , CCrvn , DCrvn , PCrvn : Parameters to create a programmable under
voltage inverse time characteristic. Description of this can be found in the Technical
manual .
CrvSatn : Tuning parameter that is used to compensate for the undesired discontinuity
created when the denominator in the equation for the customer programmable curve is
equal to zero. For more information, see the
Technical manual .
IntBlkSeln : This parameter can be set to Disabled , Block of trip , Block all . In case of a
low voltage the undervoltage function can be blocked. This function can be used to
1MRK 505 370-UUS A
Section 8
Voltage protection
Busbar protection REB670 2.2 ANSI 245
Application manual