SIRIUS 3RT2037-3NE34 — Size S2 Power Contactor with 48-80 V Coil
The Siemens 3RT2037-3NE34 is a SIRIUS-brand power contactor in the Size S2 frame, designed for switching motor loads and resistive circuits in industrial control panels. Its coil is rated for 48 to 80 V, with a pickup threshold of 0.8 times the rated value and a dropout of 1.1 times the full-scale value — meaning the coil pulls in reliably at 38.4 V and drops out at 88 V, giving a clean hysteresis band for noisy DC supplies. The main contact configuration is 18 normally open contacts and 1 normally closed contact (18 NO + 1 NC), arranged for three-pole motor switching with an auxiliary mirror contact for feedback. No separate auxiliary switch block is fitted as standard, so the built-in NC is the only signal contact on the device. Mechanical life is rated at 10 million operations typical, with switching frequencies that depend on the duty class: 800 cycles per hour in AC-1 (resistive), 700 in AC-3 (squirrel-cage motors), 400 in AC-2 (slip-ring motors), and 200 in AC-4 (plugging/inching). The AC-3e rating also allows 700 cycles per hour, matching the standard AC-3 figure for modern energy-efficient motors.
Coil and Timing Characteristics
Coil holding power is 2 VA at both 50 Hz and 60 Hz, with an inrush current peak of 1 A at 24 V, tapering to 0.3 A at 220 V. The intermediate values — 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V — show the coil's impedance rise as voltage increases, which keeps the thermal load manageable across the operating range. Opening time (from coil de-energization to contact separation) is 30 to 55 ms for both AC and DC supplies, and the arcing time is 10 to 20 ms. These figures matter for coordination with upstream short-circuit protection — the total break time of roughly 40 to 75 ms must be within the let-through energy curve of the selected fuse or MCCB.
Mounting and Integration
Fastening is by screw or snap-on mounting onto 35 mm standard mounting rail per DIN EN 60715. The mounting position allows +/-180° rotation on a vertical surface and can be tilted forward/backward by +/-22.5° on a vertical surface — useful when the contactor must fit into a tight gland-plate area or alongside busbars. Dimensions are 114 mm high, 55 mm wide, and 178 mm deep. Clearance distances: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side. The 55 mm width is the critical panel-space dimension — it occupies three 18 mm module positions on a DIN rail, so plan for three adjacent slots in the enclosure layout. Coil terminals are spring-type (cage clamp), accepting 2 x 0.5 to 2.5 mm² solid or stranded wire. Strip length for spring terminals is typically 8-10 mm; the spring mechanism eliminates the need for retorquing during thermal cycling, which is a maintenance advantage in high-vibration environments like compressor skids.
Environmental and Lifecycle
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The storage limit exceeds the operating range because it governs handling and transit, not running conditions — the contactor can sit in a cold warehouse at -55 °C but must be warmed to at least -25 °C before energizing.