Interrupting capacity and thermal derating
The Siemens SENTRON 3VA1120-4EF32-0JH0 is a 3-pole molded case circuit breaker rated for line protection with a TM240 thermal-magnetic overcurrent release. Its interrupting capacity hits 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V — the SCCR headroom you need at the service entrance or in a high-fault panel feed. The rated continuous current Iu is 20 A, and it holds that rating flat from 40 °C through 50 °C; above 50 °C it derates linearly to 18 A at 70 °C. That 18 A floor at the top of the operating range matters when the breaker sits in a hot enclosure alongside other heat sources.
Panel fit and auxiliaries
Dimensions are 76.2 mm wide, 130 mm high, 70 mm deep — a standard SENTRON 3VA footprint that drops into existing DIN-rail or screw-mount panel layouts without re-drilling. The front face carries an IP40 protection class, adequate for enclosed distribution boards. Auxiliary contact configuration is 2 auxiliary switches plus 1 trip alarm switch (HQ type); a shunt trip release (STL) is fitted as the auxiliary release. The integrated auxiliary trip order code is 3VA9688-0BL32. No undervoltage release, no ground-fault monitoring, no communication function, no phase-failure detection — this is a pure line-protection device, not a multifunction power monitor.
Environmental range
Operating temperature spans -25 °C to 70 °C; storage range is -40 °C to 80 °C. Mechanical endurance is rated at 15 000 cycles. The rated insulation voltage Ui is 800 V. Reference code per DIN EN 81346-2 is Q.