Start with the job the relay needs to perform: switching, timing, monitoring, motor overload protection or a safety function. Then check the control voltage, contact configuration, load ratings and mounting requirements. For plug-in relays, confirm the socket compatibility. Compare the exact Schneider Electric product references before ordering.

An electromechanical relay uses a coil to operate moving contacts. A solid-state relay uses electronic components to switch the load without moving contacts. Solid-state relays suit frequent, quiet switching, while electromechanical relays offer a range of contact arrangements. The right choice depends on the load, switching frequency and heat dissipation requirements.

Choose a relay rated for the control supply that operates it, including whether that supply is AC or DC. For example, a relay rated for a 24 V DC coil requires the specified DC control supply. Coil voltage and switched-load voltage are separate ratings. For a relay-and-socket assembly, check the assembly’s input rating as well.

NO means normally open; NC means normally closed. For a conventional non-latching relay, these describe the contacts when the coil is not energized. SPDT means single-pole, double-throw: one common contact switches between two connections. DPDT means double-pole, double-throw: two changeover contacts operate together. Match the contact arrangement to your circuit requirements.

Start with the full part number printed on the existing relay. Check its function, coil or input voltage, contact arrangement, load ratings and socket compatibility against the replacement datasheet. A matching shape or pin count is not enough. If the reference has been discontinued, contact your local Guillevin branch for help identifying a suitable replacement.