Motor Starters & Overloads
Contactors, thermal and electronic overload relays, trip classes, and nuisance-trip diagnosis.
Articles
Why Does the Overload Relay Trip When Motor Amps Are Normal?
Diagnose overload relay trips with normal motor amps by checking phase current, settings, phase loss, heating, start time, and the relay.
Contactor Chatter vs. Hum: Telling the Two Faults Apart
Contactor chatter and contactor hum are two different faults with almost no shared causes. Split them by contact state, then meter the coil.
Why Does a Star-Delta Starter Trip When It Switches to Delta?
Diagnose a star-delta starter that trips at delta transition by checking speed, timing, lead sequence, voltage, and overload placement.