Capacitor switching duty — not a general-purpose contactor
The 3RT2617-1BF43 is a dedicated capacitor contactor from the Siemens SIRIUS family, Size S00. It is designed for switching capacitor banks for power factor correction, where the inrush current can exceed the rated current by a factor of 20 or more. The contactor's construction — including the arcing time of 10...15 ms — is optimised for this repetitive, high-peak duty, not for motor starting or resistive loads.
DC coil at 110 V — control circuit integration
The coil is rated 110 V DC with screw-type terminals, and the operate/release time is 7...13 ms. The DC coil draws no continuous holding current after the initial surge, so it runs cooler than an equivalent AC coil and is suited for PLC-driven control panels where the 24 V DC bus is not available.
DC switching ratings — what they mean for capacitor bank selection
These are the maximum DC-1 (resistive) or DC-3 (motor) currents the main poles can interrupt. For capacitor switching, the relevant rating is the AC-6b category (not listed here directly), but the DC figures confirm the contactor's capability to break the DC link of a capacitor bank after the AC side has opened. The instantaneous contact (1 NO) provides a fast make/break for the capacitor discharge resistor circuit.