What this MCCB is and what it does
The Siemens SENTRON 3VA1220-5MH32-0CC0 is a 3-pole molded case circuit breaker (MCCB) in the starter protection version, rated for 200 A continuous current (Iu). Its 187 kA breaking capacity at 240 V and 121 kA at 415 V tell you it can safely interrupt very high fault currents on the secondary side of a distribution transformer or in a high-capacity industrial panel — not every MCCB at this frame size carries that level of interruption. At 440 V it still holds 30 kA, and at 690 V it manages 17 kA. The thermal-magnetic release is designated TM120M, and the breaker ships with an undervoltage release (UVR) and two HQ auxiliary switches (order code 3VA9608-0BB24 for the integrated auxiliary trip). This configuration is aimed at motor starter protection, where a UVR drops the load on loss of control voltage and the aux contacts report breaker status back to the PLC or safety relay.
Thermal derating — what the numbers mean for panel design
The breaker carries its full 200 A from 40 °C through 50 °C ambient. At 55 °C it derates to 192 A, at 60 °C to 188 A, at 65 °C to 184 A, and at 70 °C to 180 A. If your panel ambient runs at 60 °C — common in a sealed enclosure with drives — you lose 12 A of headroom. Plan the load side accordingly; the rated insulation voltage is 800 V, so the thermal limit, not dielectric, is the binding constraint at elevated temperatures.
Mounting and footprint
Dimensions are 158 mm high, 105 mm wide, 70 mm deep. It mounts on a DIN rail or directly to a backplate via the screw terminals. The IP40 rating on the front means it is protected against tools and wires >1 mm — fine for a closed panel, but not for washdown or outdoor exposure without an enclosure.
What to verify before you buy
The breaker does not include a trip indicator, voltage trigger, phase failure detection, ground fault monitoring, or communication function. If your application requires any of those, this is not the variant. The operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. Latching endurance is rated at 15 000 operations.