MCCB for line protection with UVR — 20 A, 121 kA at 240 V
The Siemens SENTRON 3VA1120-4EF36-0CA0 is a 3-pole molded case circuit breaker (MCCB) rated 20 A at 40 °C, designed for line protection in distribution panels. Its interrupting capacity hits 121 kA at 240 V AC, dropping to 75.6 kA at 415 V and 52.5 kA at 440 V — still strong enough for high-fault industrial feeds. At 500 V and 690 V it holds 11.9 kA, so this breaker handles low-voltage main or sub-feed duty where fault levels are substantial. An undervoltage release (UVR) is built in, tripping the breaker when supply voltage drops below a set threshold — standard for safety circuits that need to drop load on power loss. Insulation voltage is rated 800 V, so it's comfortable on 400/480 V systems with margin. Power dissipation at full load is 14.5 W — panel cooling and adjacent device spacing should account for that. The TM240 overcurrent release (thermal-magnetic, fixed) provides the 20 A trip curve.
Breaking capacity by voltage — selectivity planning
At 240 V the breaker clears 121 kA; at 415 V it's 75.6 kA; at 440 V it's 52.5 kA; at 500 V and 690 V it's 11.9 kA. These numbers govern upstream-downstream coordination — if the fault current at your secondary bus exceeds the MCCB's rating at that voltage, you need a current-limiting upstream device or a higher-rated frame.
Dimensions and panel fit
The 3VA1120-4EF36-0CA0 measures 70 mm deep, 76.2 mm wide, and 130 mm high. The 76.2 mm width (3 in) is the standard 3-pole MCCB footprint for this SENTRON frame — it fits existing 3VA panel cutouts and busbar arrangements without modification.