Siemens SENTRON 3VA1040-4ED32-0BA0 — 40 A MCCB for Line Protection
The Siemens 3VA1040-4ED32-0BA0 is a SENTRON molded case circuit breaker (MCCB) built for line protection in distribution panels. It's a 3-pole unit rated at 40 A continuous current (Iu) through 50 °C, with the TM210 thermal-magnetic release handling the overcurrent and short-circuit tripping. The breaking capacity hits 121 kA at 240 V AC — that's serious fault-clearing for a 40 A frame, meaning it can interrupt a high-energy short without welding its contacts or cascading upstream. This MCCB includes an undervoltage release (UVR) as standard — designated as design of the auxiliary release. That UVR drops the breaker if supply voltage falls below a threshold, which is useful for motor starters or safety circuits where you want the load to drop out on a brownout. The integrated auxiliary trip order code is 3VA9608-0BB11, so if you're building a panel and need that auxiliary contact wired in, that's the add-on part number to source alongside this main breaker.
Current Ratings and Thermal Derating — What They Mean for Your Panel
The 3VA1040-4ED32-0BA0 carries 40 A from 40 °C up to 50 °C ambient without derating. At 55 °C it drops to 38.4 A, at 60 °C to 37.6 A, at 65 °C to 36.8 A, and at 70 °C to 36 A. That's a gentle slope — only 10% loss at the top end — so if you're stuffing this breaker into a tight panel with other heat sources, you've got headroom. The rated insulation voltage is 800 V, which covers 480/600 V systems with margin. Mechanical endurance is listed at 15,000 operations — that's the latching endurance, meaning the number of open-close cycles the mechanism is rated for before wear. For a line-protection MCCB that sees infrequent switching (maybe a few dozen operations a year), that's effectively a lifetime supply. The front protection is IP40, so it keeps tools and fingers out but isn't sealed against dust ingress — mount it inside a panel enclosure.
Breaking Capacity Across Voltages — Coordination Reality
This breaker's interrupting rating drops as voltage climbs: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. Those numbers matter for selectivity studies — if your fault current at the panelboard is 65 kA at 415 V, this MCCB handles it cleanly. At 690 V you're limited to 11.9 kA, so on a 690 V system you'd need to verify the available fault current doesn't exceed that, or move to a higher-rated frame.
Physical Fit — Panel Integration Notes
Dimensions are 130 mm height, 76.2 mm width, and 70 mm depth. That 70 mm depth is the body depth behind the panel — it fits standard MCCB cutouts in distribution boards. The width at 76.2 mm is a 3-pole frame, so if you're replacing a 3-pole MCCB from another manufacturer, check your existing cutout width; many 3-pole MCCBs land in the 75–80 mm range. No trip indicator on the front, so fault indication relies on the undervoltage release or external annunciation.