Siemens 3VA1120-6EF36-0AD0 — 20 A SENTRON MCCB with TM240 trip
Breaking capacity is the headline number on this frame. At 240 V it clears 220 kA; at 415 V it's still 154 kA; at 440 V it holds 121 kA. Those figures put it in the high-interrupting category — sized for large transformer secondaries or bus-duct feeds where fault current runs heavy. At 690 V it drops to 17 kA, which is still adequate for most 690 V motor circuits but worth checking against the utility's available fault current. The thermal derating is published stepwise from 40 °C up to 70 °C. It carries the full 20 A through 50 °C ambient; at 55 °C it's 19.2 A, at 60 °C it's 18.8 A, at 65 °C it's 18.4 A, and at 70 °C it's 18 A. That's a shallow slope — the breaker doesn't shed much capacity until you're well above a typical 40 °C panel ambient. Useful if the enclosure sits near a heat source or in a non-conditioned space. Rated insulation voltage is 800 V, so it's rated for 690 V line-to-line systems with margin. The front face carries IP40 protection — fine for a closed panel, not for washdown exposure. Three auxiliary switches (HQ type) are built in, giving you status feedback for a PLC or remote indication without adding a side-mount accessory.
Panel fit and integration
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — standard 3VA frame size for the 20 A rating. It mounts on a DIN rail or can be screw-fixed to a backplate. The 76.2 mm width (three 25.4 mm pole pitches) matches the footprint of other 3-pole SENTRON MCCBs, so swapping in a higher or lower current frame within the same family doesn't require re-drilling the panel.