The Siemens 3RT2927-2PR11 is a pneumatically time-delayed auxiliary switch block from the SIRIUS family, designed as an off-delay (delay on de-energization) device. It provides one normally-open and one normally-closed contact, with an adjustable off-delay time spanning 10 to 180 seconds. This block mounts directly onto SIRIUS S0-frame contactors (specifically the 3RT202 series) via a clip-on fastening method, adding timed auxiliary switching without additional panel wiring or a separate timer module.
The contact ratings are voltage-dependent, reflecting real-world switching capability across control circuits: 4 A at 24 V, 2 A at 48 V, 0.7 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, 4 A at 400 V, 0.15 A at 440 V, 2.5 A at 500 V, and 1.5 A at 690 V. The maximum AC-12 rating is 10 A, which governs resistive-load switching in control applications. The off-delay accuracy is ±10% of the set time, which is typical for pneumatic timers and adequate for sequencing tasks like staggered motor start or vent damper closure after a stop command. Mechanical service life is rated at 3,000,000 switching cycles when mounted on a 3RT2.2 contactor, giving a realistic endurance figure for high-cycle applications like conveyor interlocks or press controls.
The block clips onto the front of an S0 contactor, occupying the auxiliary switch position. Its dimensions are 45 mm wide, 45 mm high, and 60 mm deep — matching the contactor footprint so it does not increase the panel width or height beyond the contactor itself. Screw-type terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or ferruled stranded wire, with AWG equivalents of 2x (18 to 14) and 2x (20 to 16).