What this MCCB is and what it does
The Siemens 3VA1150-5EF36-0KC0 is a SENTRON molded case circuit breaker (MCCB) for line protection — the primary disconnect and fault interrupter in a distribution panel, motor control center, or switchboard. It's a 3-pole unit rated for 50 A continuous current at 40 °C, and it holds that same 50 A rating all the way up to 50 °C before it starts to derate. That thermal curve matters: at 55 °C it's still good for 48 A, at 70 °C it's 45 A, so you get full nameplate capacity in most ventilated enclosures without having to oversize.
Breaking capacity — what the numbers mean for your fault duty
This breaker carries a 187 kA interrupting rating at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. Those are high-end figures for a 50 A frame — it'll clear a bolted fault on a large transformer secondary without the arc flash escalating. The 690 V rating is the one to watch if you're on a 600 V class system; 17 kA is still respectable but you need to verify the available fault current at that voltage. The insulation voltage is rated 800 V, so the breaker itself is built for 690 V line-to-line service.
Panel fit and mounting
Mounts on a DIN rail or direct to a backplate. Dimensions: 130 mm tall, 76.2 mm wide, 70 mm deep. The 70 mm depth is the key number for enclosure depth clearance — it's shallow enough for most 200 mm deep wall-mount enclosures. Front protection is IP40, so it's fine for a clean indoor panel but not for washdown areas. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.