The Siemens SENTRON 3VA1112-5EF36-0DC0 is a 3-pole molded case circuit breaker (MCCB) rated for 125 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. It's a line-protection device — meaning it's sized to protect cables and busbars, not motor loads, so don't try to hang a motor starter off it without checking the coordination study.
Breaking capacity — what the numbers mean for your fault level
This MCCB delivers 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. At 415 V — common for industrial distribution in many markets — 121 kA means it can interrupt a fault current up to that level without the arc re-striking or the case rupturing. That's a high-interrupting-capacity (HIC) class breaker; you'd spec it at the main distribution point where fault currents are highest, not downstream where 25–50 kA is usually enough. The 690 V figure of 17 kA is still respectable for a 125 A frame — some competitors drop to single digits at that voltage.
Thermal derating — the real continuous current depends on your panel temp
Rated 125 A continuous from 40 °C through 50 °C ambient. At 55 °C it's 120 A, at 60 °C it's 117.5 A, at 65 °C it's 115 A, and at 70 °C it's 112.5 A. That's a shallow derating curve — you lose only about 10 % from 40 °C to 70 °C — which is better than many older MCCB designs. If your panel runs at 55 °C (common in sealed, sun-exposed enclosures), you still get 120 A out of it. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C.
Panel fit — dimensions and mounting
Width is 76.2 mm, depth is 70 mm, height is 130 mm. That width — roughly 3 inches — is standard for a 125 A frame in the SENTRON 3VA platform. It's a screw-mount breaker, not a plug-in; you'll need busbar or cable connections. Front IP40 protection means it's fine for a clean indoor panel but not for washdown areas. The 2 auxiliary switches (HQ type) are integrated — good for status feedback to a PLC or a remote indication lamp.
Auxiliary releases and accessories
Comes with an undervoltage release (UVR) — part of the design, not an add-on. That means if control voltage drops, the breaker trips. The integrated auxiliary trip is order code 3VA9608-0BB25 — if you need to replace just that module, that's the part number to order separately. No voltage trigger, no communication function, no phase failure detection, no ground fault monitoring. This is a basic line-protection MCCB with UVR and aux contacts — nothing fancy, but reliable for the job.