S6 Current Elements 469Motor Management RelaySetpointshttp://www.GEindustrial.com/multilin 5–51GE MultilinUndercurrent PATH: SETPOINTS ZV S6 CURRENT ELEM. ZV UNDERCURRENTA trip or alarm will occurs once the magnitude Ia, Ib, or Ic falls below the pickuplevel × FLA for the time specified by the UNDERCURRENT ALARM DELAY. TheUndercurrent element is active only when the motor is running. It is blocked uponthe initiation of a motor start for the time defined by the U/C BLOCK FROM STARTsetpoint (e.g. this block may be used to allow pumps to build up head before theundercurrent element trips). A value of “0” means the feature is not blocked fromstart. If a value other than “0” is entered, the feature is disabled when the motor isstopped and also from the time a start is detected until the time entered expires.The UNDERCURRENT ALARM PICKUP level should be set lower than motor loadingduring normal operations.For example, if a pump is cooled by the liquid it pumps, loss of load may mean thatthe pump overheats. In this case, enable the undercurrent feature. If the motorloading should never fall below 0.75 × FLA, even for short durations, theUNDERCURRENT TRIP PICKUP could be set to “0.70” and the UNDERCURRENT ALARMPICKUP to “0.75”. If the pump is always started loaded, the BLOCK UNDERCURRENTFROM START setpoint should be disabled (programmed as “0”).The UNDERCURRENT ALARM DELAY or UNDERCURRENT TRIP DELAY is typically set as quickas possible, i.e. 1 second. UNDERCURRENT [Z] BLOCK UNDERCURRENTFROM START: 0 sRange: 0 to 15000 s in steps of 1MESSAGE UNDERCURRENTALARM: OffRange: Off, Latched, UnlatchedMESSAGE ASSIGN ALARM RELAYS:AlarmRange: Alarm, Alarm & Auxiliary2,Alarm & Aux2 & Aux3,Auxiliary2, Aux2 & Aux3,Auxiliary3MESSAGE UNDERCURRENT ALARMPICKUP: 0.70 x FLARange: 0.10 to 0.95 x FLA in steps of0.01MESSAGE UNDERCURRENT ALARMDELAY: 1 sRange: 1 to 60 s in steps of 1MESSAGE UNDERCURRENT ALARMEVENTS: OffRange: On, OffMESSAGE UNDERCURRENTTRIP: OffRange: Off, Latched, UnlatchedMESSAGE ASSIGN TRIP RELAYS:TripRange: Trip, Trip & Auxiliary2, Trip &Aux2 & Aux3, Trip & Auxiliary3MESSAGE UNDERCURRENT TRIPPICKUP: 0.70 x FLARange: 0.10 to 0.99 x FLA in steps of0.01MESSAGE UNDERCURRENT TRIPDELAY: 1 sRange: 1 to 60 s in steps of 1
