The Siemens 3VA1120-4EF46-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 20 A continuous rating across ambient temperatures from 40 °C to 55 °C, derating to 19 A at 60 °C and 65 °C, and 19 A at 70 °C — so the full 20 A holds through typical panel ambient conditions, with a small derate only above 55 °C.
Breaking capacity and selectivity
Rated breaking capacity reaches 121 kA at 240 V AC, dropping to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. The 121 kA figure at 240 V means this breaker handles very high fault currents on low-voltage distribution — typical for transformer-fed main or sub-main positions where the available fault current is high. At 415 V the 75.6 kA still covers most industrial panelboards. The 11.9 kA at 690 V is the limiting value for higher-voltage installations.
Overcurrent release and ratings
Fitted with a TM240 thermal-magnetic overcurrent release — the thermal element handles overloads, the magnetic element handles short-circuits. The 4-pole configuration suits three-phase plus neutral or three-phase with switched neutral applications. Insulation voltage is rated 800 V, which gives headroom for 690 V systems. Maximum power loss is 12 W, a figure to consider for thermal dissipation in a sealed enclosure.
Physical fit and environment
Dimensions are 70 mm depth, 101.6 mm width, 130 mm height. Front protection is IP40.