Undercurrent feature is blocked by operation of Reconnection inhibit
feature.
Reactive power overload feature:
Operation QOL =Enabled; to enable this feature
UP_QOL =130% (of SCB MVAr rating); Reactive power level required for pickup.
Selected value gives pickup recommended by international standards.
tQOL =60s; Time delay for reactive power overload trip
Harmonic voltage overload feature:
OperationHOL =Enabled; to enable this feature
Settings for definite time delay step
HOL_DT_V =200% (of SCB voltage rating); Voltage level required for pickup
tHOL_DT =10s; Definite time delay for harmonic overload trip
Settings for IDMT delay step
PU_HOL_DT_V =110% (of SCB voltage rating); Voltage level required for pickup of
IDMT stage. Selected value gives pickup recommended by international standards.
k_HOL_IDMT =1.0; Time multiplier for IDMT stage. Selected value gives operate
time in accordance with international standards
tMax_HOL_IDMT =2000s; Maximum time delay for IDMT stage for very low level of
harmonic overload
tMin_HOL_IDMT =0.1s; Minimum time delay for IDMT stage. Selected value gives
operate time in accordance with international standards
Restrike detection
Opening of SCBs can be quite problematic for certain types of circuit breakers (CBs).
Typically such problems are manifested as CB restrikes.
In simple words this means that the CB is not breaking the current at the first zero
crossing after separation of the CB contacts. Instead current is re-ignited and only
braked at consecutive current zero crossings. This condition is manifested as high
current pulses at the moment of current re-ignition.
To detect this CB condition, the built in overcurrent feature can be used. Simply, any
start of the overcurrent feature during breaker normal opening means a restrike.
Section 3 1MRK504116-UUS C
IED application
500
Application manual
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