Integrator note: 3VA1120-3GF42-0AA0
The Siemens 3VA1120-3GF42-0AA0 is a SENTRON-series 4-pole molded case circuit breaker (MCCB) with a 20 A continuous rating and a TM240 thermal-magnetic release — the '240' indicates the fixed trip unit's thermal calibration, so no field-adjustable overload pickup. Breaking capacity runs 75.6 kA at 240 V AC, 52.5 kA at 415 V, and 32 kA at 440 V; at 500 V and 690 V it holds 11.9 kA. That's a strong interrupt rating for a 20 A frame — useful for high-fault panels where a cheaper MCB would need upstream fuses.
Panel fit and thermal derating
Footprint is 101.6 mm wide by 130 mm tall by 70 mm deep — standard 4-pole MCCB envelope for a 100 A frame. Front protection is IP40, so it's fine inside a closed panel but not for washdown areas. The breaker carries its full 20 A from 40 °C through 55 °C; at 60 °C and 65 °C it derates to 19 A, and at 70 °C it's still 19 A. That's a shallow derating curve — good for a crowded enclosure with limited airflow.