125 A MCCB with TM240 release — interrupting capacity across the voltage range
The Siemens SENTRON 3VA1112-5EF36-0BH0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current Iu of 125 A, configured for line protection duty. Its TM240 thermal-magnetic overcurrent release handles both overload and short-circuit conditions without an external trip unit. The interrupting capacity scales with system voltage: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V — so the same breaker can be specified across multiple distribution voltage levels as long as the available fault current stays under the applicable rating. Rated insulation voltage Ui is 800 V, which covers 480/277 V and 600 V nominal systems with margin. The breaker carries an IP40 protection class on the front — suitable for enclosed panel mounting where the front face is accessible but the interior is protected from tool entry and solid objects larger than 1 mm.
Thermal derating and ambient temperature profile
The 125 A rating holds flat from 40 °C through 50 °C ambient. Above that, the breaker derates linearly: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. If the panel ambient runs hot — say, near a drive cabinet or in a non-conditioned enclosure — the continuous load must be sized against the derated figure, not the nameplate 125 A. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Integrated undervoltage release and auxiliary contact block
This variant includes an undervoltage release (UVR) as the integrated auxiliary release — designated design type undervoltage release (UVR). When line voltage drops below the release threshold, the breaker trips, which is standard for applications requiring under-voltage protection on motor feeders or safety circuits. The auxiliary contact version is 2 auxiliary switches + 1 trip alarm switch HQ, giving three separate signal paths: two for status (open/closed) and one dedicated to trip indication. A mechanical trip indicator is also present on the front.
Dimensions and panel fit
Width is 76.2 mm (roughly 3 inches), depth is 70 mm, height is 130 mm. The 3-pole footprint matches the standard SENTRON 3VA family spacing, so a panel laid out for a 3VA125 A frame accepts this unit without re-drilling the mounting plate or re-routing bus bars. The 76.2 mm width is the critical dimension for multi-breaker grouping on a DIN rail or busbar stack — verify that the adjacent breaker or blanking plate leaves at least that pitch.