What this part is and what it does
The Siemens 3RT1647-1AP61 is a SIRIUS capacitor contactor — a three-pole switching device purpose-rated for AC-6 duty, specifically for switching capacitor banks for power factor correction. Its headline rating is 50 kVAr at 400 V, meaning it can switch a capacitor bank of that reactive power without excessive inrush or contact welding, per the AC-6 utilization category in IEC 60947-4-1. The coil is wound for 220 V AC at 50 Hz and 220…240 V AC at 60 Hz, so it pulls in reliably on a standard 220 V control supply. The contactor carries three normally-open main poles and one normally-open auxiliary contact, all screw-type terminals.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm DIN rail per DIN EN 50022. The 70 mm width matches the SIRIUS S3 frame footprint, so it occupies one standard 70 mm slot in a panel. Side-by-side mounting is permitted with no additional spacing, which keeps the panel fill factor tight. Dimensions are 167 mm high by 70 mm wide by 183 mm deep. The front achieves IP20 only when the supplied cover or box terminal is fitted; the terminal area itself is IP00, so the contactor expects enclosure protection for the wiring zone.
What the ratings mean for your selection
The AC-1 rating of 90 A at 400 V tells you the contactor can handle 90 A of resistive load continuously. That is not the capacitor-switching rating — the AC-6 rating of 50 kVAr is the one that governs capacitor bank duty, because capacitor switching imposes higher inrush and requires specific contact materials and arc-chamber design. Operating ambient temperature range is -25 to +60 °C, which covers most indoor panel environments. The substance prohibitance date of 05/01/2012 indicates RoHS compliance from that date forward.