What the ratings mean for fit
The Siemens 3VA1220-5GF42-0AC0 is a SENTRON molded case circuit breaker (MCCB) rated for continuous current of 200 A across ambient temperatures from 40 °C to 50 °C, derating to 176 A at 70 °C. The TM240 thermal-magnetic release provides fixed thermal and magnetic trip settings for line protection. Interrupting capacity is 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V — these are the fault currents the breaker can safely clear at each voltage level without welding or rupturing. The 4-pole construction (3 phases + neutral) suits three-phase systems where the neutral needs overcurrent protection. Rated insulation voltage is 800 V, covering most low-voltage distribution panels. Mounting dimensions are 140 mm wide, 158 mm high, 70 mm deep — a standard 4-pole MCCB footprint for panel mounting. The breaker includes 2 auxiliary switches (HQ design) for status feedback to a PLC or indication lamp. Maximum power loss is 42 W at rated current, relevant for enclosure thermal calculations.