What this starter does in a panel
The 3RA2120-0KA23-0AP6: This is a non-fused motor starter from the Siemens SIRIUS family, built as a direct starter — meaning it combines a contactor and a thermal overload relay in one assembly, ready to snap onto a DIN rail or screw-mount with the included push-in lug. The supplied contactor is a 3RT2023-1AP60, and the link module 3RA2921-1AA00 ties the contactor to the overload block — no extra wiring between them, which saves panel space and cuts down on termination errors.
Rated voltage and motor power — what it handles
Rated at 690 V, with an AC-3 maximum of 690 V, this starter covers common three-phase systems at 400 V, 480 V, 500 V, and 600 V without derating the voltage class. Motor power ratings are 370 W at 400 V, 550 W at 500 V, and 750 W at 690 V — so it's sized for small motors, fractional-horsepower loads like pumps, fans, and conveyors in a control panel. The control coil accepts 176–242 V at 50 Hz and 192–264 V at 60 Hz, which means it works on standard 230 V control transformers in most regions.
Trip class and overload protection
The overload release is thermal bimetallic, CLASS 10 — that's the standard trip class for standard-duty motors, giving enough time for the motor to start without tripping, but fast enough to protect against sustained overloads. Because it's thermal, it doesn't need an external power supply for the overload function — it responds to motor current heating the bimetal strip, which is simple and field-proven.
Mounting and panel fit
Snap-mounted to DIN rail or screw-mounted with an additional push-in lug — the mounting position is vertical, and the clearances are 30 mm upwards, 10 mm forwards, 10 mm downwards, and 9 mm at the side. Dimensions are 97.1 mm deep, 45 mm wide, and 193.1 mm high — the S0 size load feeder footprint is compact enough for a crowded panel but leaves room for finger-safe wiring.