How to identify contactors
Contactors switch motors and other heavy loads under the control of a coil circuit.
Have one in front of you? Photograph it and get an evidence-backed identification.
Identify from a photoIdentification clues
- —Rating plate with AC-3 current/kW
- —Coil voltage label (often colour coded)
- —Terminal markings 1/L1–6/T3, A1/A2, auxiliary 13/14 etc.
- —DIN-rail or panel mount footprint
- —Fitted auxiliary blocks or overloads
Common types
- —AC motor contactor
- —DC contactor
- —Reversing pair
- —Capacitor-duty contactor
- —Mini contactor
Typical failure modes
- —Contact erosion
- —Coil burn-out
- —Humming from dirty pole faces
- —Mechanical interlock failure
- —Loose terminals overheating
What a replacement must match
- —Match AC-3 rating and pole count
- —Match coil voltage and frequency
- —Check accessory compatibility (aux blocks, overload)
- —Match mounting and terminal type
Photos that help identification
- —Photograph the full side label
- —Show the coil terminal label
- —Include any fitted accessories
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Related guides
General reference information. Always verify against the manufacturer’s documentation before ordering or installing.