The Siemens SENTRON 3VA1120-6EF32-0HA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection duty. It carries a rated continuous current Iu of 20 A and delivers a 220 kA interrupting capacity at 240 V — that's the figure that governs fault clearance on a 240 V bus. The interrupting curve drops to 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 690 V, so size the breaker to the available fault current at your system voltage.
Ratings and thermal performance
The TM240 thermal-magnetic overcurrent release holds 20 A continuous from 40 °C up to 50 °C without derating. Above that, it steps down: 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. If this breaker sits in a warm enclosure — say, near a transformer or in a sunlit cabinet — those derated numbers are the ones that matter for avoiding nuisance trips. Rated insulation voltage Ui is 800 V, so the breaker is comfortable on 480 V and 600 V class systems. The front carries IP40 protection — fine for a dry panel interior, but not for washdown areas.
Dimensions and panel fit
This MCCB measures 76.2 mm wide by 130 mm tall by 70 mm deep. That 76.2 mm width — three modules on a standard 25 mm DIN-rail pitch — is what determines how many breakers fit in a row. The 70 mm depth matters when the enclosure backplate has limited clearance to the door or a rear bus. No auxiliary contacts are fitted as shipped; the shunt trip (STL) release is built in, and the integrated auxiliary trip is order code 3VA9688-0BL30 if you need to add indication later.