What the ratings mean for fit
The Siemens 3VA1120-5EF32-0BA0 is a SENTRON molded case circuit breaker (MCCB) rated for 20 A continuous at 40 °C, with a thermal-magnetic overcurrent release (TM240). It carries a full-rated 20 A up to 55 °C, then derates to 19 A at 60 °C through 70 °C — so in a hot cement kiln control room or a packed enclosure, you still get 19 A before the trip curve shifts. The 187 kA interrupting capacity at 240 V means it can clear a massive fault without upstream coordination issues; at 415 V it still breaks 121 kA, and at 690 V it holds 17 kA. That SCCR headroom makes it a solid choice for line-side protection where fault currents are high. The 3-pole design with an undervoltage release (UVR) built in means it drops the load if control voltage is lost — useful for motor circuits where you want a guaranteed stop on power dip. Rated insulation voltage is 800 V, so it's comfortable on 480 V or 600 V class systems. The TM240 trip unit is thermal-magnetic: thermal for overload, magnetic for short circuit, no electronic adjustments.
Panel fit and integration
The MCCB measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard SENTRON 3VA footprint. It mounts on a DIN rail or can be screw-fixed to a backplate. The 70 mm depth means it clears most shallow enclosures without forcing a deeper gland plate. Power loss is 14.5 W maximum, so factor that into your thermal budget if you're stacking several breakers in a sealed panel.