What it is and what it does
The Siemens SENTRON 3VA1220-4EF42-0BH0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection — the primary overcurrent protective device for a feeder or main in a distribution panel. It carries a continuous current of 200 A at 40 °C and derates predictably through 70 °C. The breaking capacity at 240 V is 121 kA; at 415 V it is 75.6 kA; at 440 V it is 52.5 kA; at 500 V it is 17 kA; and at 690 V it is 11.9 kA. That means it can safely interrupt very high fault currents on a 240 V or 415 V system without the arc flashing over — critical for protecting downstream switchgear and cables.
Key ratings and what they mean for fit
The 200 A frame at 40 °C is the continuous current the breaker can carry without tripping under normal load. If your panel ambient runs higher, the derating curve is explicit: 194 A at 55 °C, 188 A at 60 °C, 182 A at 65 °C, 176 A at 70 °C. The rated insulation voltage is 800 V, so the breaker is suitable for 690 V systems with margin. The undervoltage release (UVR) lets you trip the breaker on loss of control voltage — common in safety circuits or remote shutdown schemes. The auxiliary switch complement is 2 auxiliary switches plus 1 trip alarm switch HQ, giving status feedback for the open/closed and tripped conditions. Power loss at rated current is 44.5 W — factor that into enclosure thermal rise.
Panel integration and mounting
The 3VA1220-4EF42-0BH0 mounts on a DIN rail or can be screw-fixed to a backplate. Dimensions: width 140 mm, height 158 mm, depth 70 mm. The 70 mm depth is the projection from the mounting surface to the front of the breaker — important for gland-plate clearance and door swing. The 4-pole configuration means it switches all three phases plus neutral, so it is the right choice for a 3-phase + N distribution board.