What this MCCB carries and where it fits
The Siemens 3VA2040-8HN42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 40 A continuous current at 40 °C, with a 4-pole configuration and an ETU350 electronic trip unit. It's designed for line protection — the primary overcurrent safeguard on a feeder or distribution branch in an industrial panel. The 800 V rated insulation voltage and 440 kA interrupting capacity at 240 V give it headroom for high-fault service-entrance or sub-distribution applications where short-circuit current runs high. IP40 on the front means it's suited for enclosed panel mounting, not open washdown areas.
Breaking capacity across voltage levels
Interrupting ratings drop as line voltage rises: 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. That 52.5 kA at 690 V is still well above typical industrial SCCR requirements for 600 V class panels, so this breaker doesn't force an upstream current-limiting fuse for most installations.
Dimensions and panel fit
The breaker measures 86 mm deep, 140 mm wide, and 181 mm high. That 140 mm width is the standard 4-pole MCCB footprint for this SENTRON frame size — it occupies four 35 mm DIN spaces if mounted on a DIN rail, or bolts into a panel-mount base. Verify the busbar or lug kit spacing against your existing panel layout, but the form factor matches the 3VA2 frame family.
Trip unit and thermal performance
The ETU350 electronic trip unit provides adjustable overload and short-circuit protection without the thermal drift of a bimetal strip. Rated current holds flat at 40 A from 40 °C through 70 °C ambient — no derating needed across that range, which simplifies panel design in warm enclosures. Maximum power loss is 1.2 W per pole, negligible for ventilation planning.
Environmental and storage limits
Operating temperature range is -25 °C to 70 °C; storage range extends from -40 °C to 80 °C. The wider storage limits matter if this breaker sits in an unheated warehouse or on a shelf in a plant that cycles temperature — it's fine for cold storage, just not energized below -25 °C.