SIRIUS S3 contactor, 20-33 VDC coil, screw terminals
The Siemens 3RT2545-1NB30 is a SIRIUS-branded contactor in the S3 frame size, built for switching loads up to the rated current of its coil voltage range. The coil is rated 20-33 VDC with a pickup threshold of 0.8x rated value and a dropout of 1.1x full-scale value — meaning it pulls in reliably at 16 V and drops out above 36 V, giving clean margin on a nominal 24 VDC control bus.
Switching capacity at common control voltages
The contactor's switching current varies sharply with the load voltage — a key detail for BOM fit. At 24 VDC rated value it switches 10 A; at 48 VDC that drops to 2 A, and at 125 VDC it handles 0.9 A. These numbers define the usable load envelope, not just a single maximum. Inrush current peaks at 6.5 A, so the control transformer must be rated for that surge without voltage sag.
Mechanical endurance and operating cycle limits
Rated for 10 million mechanical operations typical, with a maximum switching rate of 900 operations per hour in AC-1 duty. The operating times are 38-57 ms for both AC and DC coil supply, and the arcing time is 10-20 ms — consistent with a standard S3 contactor designed for frequent cycling in conveyor or pump control.
Termination, clearance, and environmental limits
Main power terminals accept stranded wire from 6 mm² up to 70 mm² (single conductor) or 2x 16 mm². Auxiliary terminals take solid or stranded 0.5-2.5 mm². All are screw-type — no spring-cage option on this variant, so plan for screwdriver access during termination. Clearance requirements: 10 mm above and below, 10 mm to the side, 0 mm forward and backward. The auxiliary switch is included as standard — no separate add-on needed for basic status feedback.
This means the part is still available through standard Siemens distribution channels. For volume or project-buy requirements, submit an RFQ for a firm lead-time and price-break quote.