Contact layout and response time — what 10 ms means in a safety circuit
The G9SA321T15ACDC24 carries a 3NO main contact set plus a single NC auxiliary (1NC), rated for 5 A switching current on the AC side. That 3NO+1NC arrangement is the standard force-guided mirror contact pair — the NC follows the NO state, so a stuck NO is detectable by the safety controller via the NC feedback loop. Response time is 10 ms from coil de-energisation to contact open. In a Category 3 or 4 safety function (per ISO 13849-1) this sets a floor on the total system reaction — the PLC scan cycle and the actuator response stack on top of this relay's 10 ms window.
Coil supply and mounting — dual-voltage flexibility
Coil accepts both 24 VAC and 24 VDC without jumper changes — one part number covers both control supply types. DIN rail mount with an integral retaining clip — snaps onto 35 mm symmetrical rail per EN 60715. The screw terminals are captive; the relay body is keyed so it cannot be inserted 180° reversed.
Service life and end-of-life planning
Mechanical life is rated at 5 million cycles; electrical life under full 5 A resistive load is 100,000 cycles. The electrical life figure is the procurement-relevant one — at 5 A switching the contact wear from arc erosion sets the replacement interval, not the mechanical cycle count.