4PDT mechanical timer, 0.1 sec to 10 min window
The Omron H3YN-4 AC24 is a multi-function mechanical-relay timer in the H3YN series, giving a buyer four form-C contact sets in one plug-in package — useful when a single timer has to drive independent circuits from one timing source, like a coil plus an indicator plus an interlock. The 4PDT (4 Form C) layout keeps wiring centralised on one base rather than chaining two DPDT timers together. Delay runs from 0.1 sec to 10 min on a hand-dial adjustment, which covers the bulk of panel-builder timing duties — star-delta staging, purge delays, conveyor dwell, and pulse-stretching — without forcing the integrator out to a separate longer-range model. Timing is initiated by input voltage, so the timer starts the moment the coil is energised rather than waiting for a separate trigger contact.
Coil, contacts, and the 250 VAC ceiling
Coil voltage is fixed at 24 VAC — that pins the part to a 24 VAC control transformer or PSU, and excludes 24 VDC or 120 VAC installations from a drop-in swap. The 3 A at 250 VAC contact rating on each of the four poles governs what the timer can switch directly; for higher-current motor or heater loads the output should feed an interposing contactor rather than carrying the load itself. Socketable plug-in mounting is the practical hook for the field — the timer drops onto an 8-pin octal or compatible base, so a failed unit on the line is a two-minute swap with the hand dial and DIP switches pre-set on the replacement. The 0.1 sec lower bound is what makes the same part usable as a short pulse generator, not just a long on-delay.
Production status and the BOM decision
The H3YN-4 AC24 carries an Active product status with a mature lifecycle stage, meaning the part is still on the manufacturer's book but is no longer the newest generation — a common pattern where Omron continues to ship an established timer because the installed base and socket pinout are locked into existing panel designs. For a new panel, this is a fit-and-forget line item; for a maintenance BOM, it is a long-tail spare that is still orderable.