tUC =5s; Time delay for undercurrent tripUndercurrent feature is blocked by operation of Reconnection inhibitfeature.Reactive power overload feature:Operation QOL =Enabled; to enable this featureUP_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 tripHarmonic voltage overload feature:OperationHOL =Enabled; to enable this featureSettings for definite time delay stepHOL_DT_V =200% (of SCB voltage rating); Voltage level required for pickuptHOL_DT =10s; Definite time delay for harmonic overload tripSettings for IDMT delay stepPU_HOL_DT_V =110% (of SCB voltage rating); Voltage level required for pickup ofIDMT stage. Selected value gives pickup recommended by international standards.k_HOL_IDMT =1.0; Time multiplier for IDMT stage. Selected value gives operate timein accordance with international standardstMax_HOL_IDMT =2000s; Maximum time delay for IDMT stage for very low level ofharmonic overloadtMin_HOL_IDMT =0.1s; Minimum time delay for IDMT stage. Selected value givesoperate time in accordance with international standards7.10.3.1 Restrike detectionOpening 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 crossingafter separation of the CB contacts. Instead current is re-ignited and only braked atSection 7 1MRK 505 337-UUS -Current protection228Application manual
