The Schneider A9E21183 is an Acti9 iRCC compressor control relay — a dedicated device that prevents a compressor from restarting too quickly after a power loss or fault, protecting the motor and pressure system from short-cycling. It's rated for 8 A at 250 V AC (cos φ = 1) on a single C/O contact set, with a 230 V AC 50/60 Hz control supply. The adjustable time delay covers 3 to 6 minutes, set via a rotary knob, with a separate wiring selection for the measurement range.
The 8 A rated operational current at 250 V AC covers the control circuit of most small-to-mid-size compressors — the relay switches the contactor coil or the compressor's own control logic, not the motor power directly. The 3–6 minute adjustable delay is the key parameter: set it to match the compressor manufacturer's minimum off-time to avoid restarting against head pressure. The tripping threshold is ±5 % of Us for undervoltage and ±15 % of Us for overvoltage, so it responds to supply sags that could stall the compressor but tolerates normal line fluctuations. Mounting is on a 35 mm symmetrical DIN rail, 4 pitches wide (36 mm), with a fixed mounting mode — no clip-on adapter needed. The tunnel-type terminals accept up to 6 cables of 1.5 mm² rigid, which is adequate for the control wiring in a typical compressor panel. Local signalling is via a green LED for power on and a red LED for fault, plus a control power supply indicator. This helps during commissioning and fault-finding — you can see at a glance whether the relay has power and whether it's tripped on an undervoltage or overvoltage condition.
Deployment context
This relay is designed for compressor control panels — typically in HVAC, refrigeration, or compressed-air systems where a timed restart delay protects the compressor from short-cycling. It sits on a DIN rail inside the panel, wired between the control supply and the compressor contactor coil. The accuracy error of ±10 % on the time delay is acceptable for this application; the delay is a safety margin, not a precision timing function.