SIRIUS timing relay, ON-delay only, adjustable 0.5–10 s
The Siemens 3RT1926-2CH21 is a SIRIUS timing relay providing a single-function ON-delay with an adjustable time range of 0.5 to 10 seconds. It accepts a universal control supply of 90–240 V AC (50/60 Hz) or DC, making it suitable for panels fed from standard 120 V or 230 V control transformers without needing a separate DC power supply. The recovery time between cycles is 50 ms, which governs how quickly the relay can be re-triggered after a reset — relevant for rapid-cycle applications like conveyor indexing or pump alternation.
Mounting and panel fit
The relay clips onto a 35 mm DIN rail and occupies a 45 mm wide slot — one standard modular device width. Height is 26 mm, depth 50 mm. Mounting position is unrestricted, so it can be placed horizontally or vertically inside a cabinet without derating. The compact footprint leaves room alongside contactors or overload relays in a motor starter bucket.
Environmental and wiring
Operating temperature range is –25 to +60 °C; storage and transport tolerate –40 to +85 °C. Degree of pollution 3 means it is rated for the conductive-dust and humidity conditions typical of industrial control panels. Screw terminals accept 2x (20–14) AWG solid or 18–14 AWG stranded. Basic insulation suits it for installation in grounded metal enclosures.