What the ratings mean for fit
The Siemens SENTRON 3VA1120-6EF36-0AF0 is a 3-pole molded case circuit breaker (MCCB) rated 20 A continuously at up to 55 °C ambient, derating to 19 A at 60–70 °C — so in a warm panel you lose 1 A of headroom above 55 °C. The TM240 overcurrent release provides fixed thermal-magnetic protection for line (cable/feeder) duty, not motor or generator protection. Breaking capacity is the standout: 220 kA at 240 VAC, 154 kA at 415 VAC, 121 kA at 440 VAC, and still 17 kA at 500/690 VAC. That 220 kA at 240 V means it can interrupt very high fault currents typical near large transformers or in high-capacity distribution — a standard 10 kA or 25 kA MCCB would fail to clear that fault. The 800 V rated insulation voltage (Ui) confirms the internal clearances support 690 V system use. Power loss is 12 W maximum, which matters for thermal budgeting in a sealed enclosure — a panel with several breakers at full load needs to account for that heat. The auxiliary switch configuration (1 auxiliary + 1 trip alarm, HQ design) allows remote status feedback for the breaker's position and trip condition without an external relay.
Integration and mounting
Dimensions are 70 mm deep, 76.2 mm wide, 130 mm tall — a 3-pole MCCB that fits standard panel-mount cutouts. The 76.2 mm (3 in) width per pole is typical for SENTRON 3VA frames; verify the existing bus-bar spacing if replacing another brand. The trip indicator is present, undervoltage release is not, and no communication function is built in — this is a straight line-protection breaker with no remote trip or metering.