ABB Relion 670 Series Applications Manual page 258

Section 10
Unbalance protection
UMin> : This setting is used to set the minimum bus voltage or equivalent tap voltage level to
release the function for operation in % of UBase. The typical value is 50%.
VoltRatioL1 : Set the tap voltage to bus voltage ratio for phase L1 (U
VoltRatioL2 : Set the tap voltage to bus voltage ratio for phase L2 (U
VoltRatioL3 : Set the tap voltage to bus voltage ratio for phase L3 (U
URatioVar> : Set the threshold limit for percentage variation of calculated voltage ratio from
set voltage ratio (
change between calculated and set voltage ratio.
UdifWrn> : This setting is used to set the warning level in % of UBase. This setting can be set
just above the natural errors so that it operates reliably on the failure of one or two elements.
The typical value is 5%.
tDefWrn : This setting is used to set the definite delay for warning signal in seconds. The
typical value is 5 seconds.
UdifAlm> : This setting is used to set the alarm level in % of UBase. This setting can be of
50%-75% of the trip level.
tDefAlm : This setting is used to set the definite delay for alarm signal in seconds. The typical
value is 5 seconds.
Udif> : This setting is used to set the trip level in % of UBase. This setting can be set at which
the healthy unit voltage is at the verge of exceeding 110% of its nominal voltage. The typical
value is 10%.
BlockTrip : This setting is used to control the activation of the trip outputs.
• If this setting is set to
and L3) and TRIP are enabled.
• If this setting is set to
and L3) and TRIP are disabled.
CurveType : This setting can be set to either Definite time or Programmable .
• If this setting is set to
operation.
• If this setting is set to
programmable curve.
tDefTrip : This setting is used to set the definite delay for trip signal in seconds. The unbalance
protection function trip should have enough time delay to avoid false operations due to inrush,
system ground faults, switching of nearby equipment, and asymmetrical pole operation of the
energizing switch. For most applications, the typical value is 0.1 second.
The settings below are taken with reference to the programmable curve, refer
manual for more information.
k : Set the time multiplier for the programmable curve.
tACrv : Set the programmable curve parameter A.
tBCrv : Set the programmable curve parameter B.
tCCrv : Set the programmable curve parameter C.
tDCrv : Set the programmable curve parameter D.
252
VoltRatioLx ). This setting can be used to provide a prior indication on high
Trip enabled , then the trip outputs TRLx (where Lx = Phase L1, L2,
Trip disabled , then the trip outputs TRLx (where Lx = Phase L1, L2,
Definite time , then the definite delay is considered for the trip
Programmable , then the delay for the trip operation is based on the
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1MRK 511 401-UEN Rev. K
/U ).
TapL1 L1
/U ).
TapL2 L2
/U ).
TapL3 L3
Technical
Bay control REC670
Application manual