What it is and what it does
The Siemens SENTRON 3VA1220-4EF42-0DC0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection — meaning it sits at the incoming feeder or main distribution point, not downstream on a motor branch. It carries a continuous 200 A at 40 °C through 50 °C, then derates linearly to 176 A at 70 °C, which is the thermal limit you design your enclosure around. The 800 V rated insulation voltage gives headroom for 690 V systems without creeping along the margin.
Breaking capacity — what the numbers mean for your fault study
This breaker delivers 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. Those are the interrupting ratings at each voltage level — not a single number you derate. If your service entrance fault current is 100 kA at 480 V, this breaker covers it with margin. At 690 V the 11.9 kA figure is the hard limit; don't push it past that.
Built-in auxiliaries and release
Factory-fitted with 2 auxiliary switches HQ and an undervoltage release (UVR). The UVR trips the breaker when control voltage drops below a threshold — standard for emergency-stop chains or undervoltage protection schemes. No ground-fault monitoring on this variant, so if you need GF protection you either add an external module or spec a different 3VA suffix.
Physical fit and panel layout
Dimensions: 140 mm wide, 158 mm tall, 70 mm deep. That 70 mm depth is the body only — add clearance for the handle throw and cable bending radius. At 44.5 W maximum power loss, you need to account for heat dissipation in the enclosure; don't stack it tight against other high-loss devices without a thermal calculation.