Sepam - HV/MV Protection and control units (ENG) - Trinet

RestartBlock diagramlogic input I1 closedlogic input I17 drawn outtime-del. pos. seq. U/V set point 1(load shed. set point)inst. pos. seq. U/V set point 2(correct voltage)&pos. seq. U/V set point 2(correct voltage)(=1 if load shedding)≥1&t 0T90 tT6 = 200 mscircuit breakerdiagram:closing order T6:pulse calibrationinst. pos. seq. U/V set point 1(load shed. set point)≥1t 0T8&&contactor diagram:closing orderT8: maximum voltage sag duration enabling restart.T9: restart staggering time delay.ApplicationThis function is used for automatic motor restart aftera shutdown brought about by a voltage sag(load shedding).PrincipleThe restart function is combined with the load sheddingfunction. It enables staggered restart of process motorswhen the voltage sag that triggers load shedding is ofshort duration.OperationAfter tripping caused by a voltage drop in the mainspower supply, detected by set point 1 of the positivesequence overcurrent protection, 2 situations mayoccur:c the duration of the voltage drop is greater than timedelay T8; tripping is final. External action is required forrestart,c the duration of the voltage drop is less than timedelay T8; a restart order is given. Time delay T9enables motor restart orders to be staggered in orderto avoid overloading the network.Restart enabling is detected after set point 2 of theundervoltage protection (function F382) drops out.This set point enables the return of voltage to bedetected regardless of the load shedding set point(typical setting: 85% Un).The restart order transmitted by this function fits into the open / close controlscheme.For circuit breaker control schemes, a 200 ms pulse is obtained on the closing coilby using time delay T6.For contactors, the pulse on the closing coil is calibrated using time delay T2.Please noteThis function may not be activated with the control scheme for latched ordercontactors (see open / close control function).CommissioningThe restart function is available on Sepams that include positive sequenceundervoltage protection. The function is linked to the load shedding function.Settings to be enteredc load shedding set point: time-delayed set point 1 of the positive sequenceundervoltage protection (F381) (typically: 30 to 70% Un),c restart enable: instantaneous set point 2 of the positive sequence undervoltageprotection (F382) (typically: 85% Un),c time delay T8: maximum voltage sag duration,c time delay T9: restart staggering time delay (setting range: 0.05 s to 655 s, defaultsetting: 200 ms), the T9 setting must be greater than T the time delay between startsof the "number of starts" protection (0.5 s by default),c time delay T6 to 200 ms (for circuit breaker control diagrams only),c To disable the restart function, inhibit set point 2 of the positive sequenceundervoltage protection (F382): set to 999 kV (default setting).Settingsc via the pocket terminal:v P SEQ U/V1 F381 and P SEQ U/V2 F382 headings in the protection menuto set the set points,v timer heading in the program logic menu for T6,T8 and T9.c via the communication link.mains UUnUs2Us1Ttload shedding restart if T < T81/22 Control and monitoring functions