How to identify relays
A relay uses a small control signal to switch a separate, usually higher-power, circuit.
Have one in front of you? Photograph it and get an evidence-backed identification.
Identify from a photoIdentification clues
- —Coil voltage and type (AC/DC) printed on the housing
- —Contact rating (e.g. amps at a stated voltage) and contact form (SPDT, DPDT)
- —Pin count and pitch, or socket base style
- —Wiring diagram moulded on the side of the case
- —Manufacturer logo and series code
Common types
- —PCB signal relay
- —Plug-in / ice-cube relay
- —Automotive relay
- —DIN-rail interface relay
- —Solid-state relay
- —Safety relay
Typical failure modes
- —Welded or pitted contacts
- —Open coil
- —Contact bounce or chatter from low coil voltage
- —Overheated socket
- —Mechanical wear past rated cycles
What a replacement must match
- —Match coil voltage and AC/DC
- —Match or exceed contact rating for the load type
- —Match pinout and socket
- —Check approvals required for the application
Photos that help identification
- —Photograph every printed face
- —Show the pin side square-on
- —Include the socket if plug-in
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Related guides
General reference information. Always verify against the manufacturer’s documentation before ordering or installing.