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Is a Line contactor or Isolation contactor ahead of the soft start, required?
Altistart 22, ATS22
All models and serial numbers
The purpose of the line contactor is to provide a means of removing AC line voltage from the softstart. Due to leakage currents through the solid state switches, hazardous voltages can be present on the load side of the softstarter when power is applied to the line side of the softstarter.
A line or isolation contactor such as KM1 shown in wiring diagrams, located in the Annex of the ATS22 Users Manual (BBV51330) is strongly suggested but not required.