What it is and what it does
The Siemens SENTRON 3VA2140-7JQ32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current. It's built for line protection — meaning it guards cables and busbars against overloads and short circuits, not motor starts. The key number here is the breaking capacity: 330 kA at 240 V AC. That's high enough for most low-voltage main distribution boards, so it can sit downstream of a large transformer without worrying about through-fault current exceeding the breaker's interrupt rating.
Breaking capacity across voltages
This MCCB's interrupt rating drops as voltage rises: 242 kA at 415 V and 440 V, 187 kA at 500 V, and 3.7 kA at 690 V. That steep drop at 690 V means it's not the right choice for a 690 V distribution board unless the available fault current is well under 3.7 kA. For 400 V-class panels, the 242 kA figure gives plenty of headroom for selective coordination with downstream breakers.
Thermal derating and ambient temperature
The continuous current rating holds at 40 A from 40 °C all the way up to 70 °C ambient. That's unusual — most MCCBs start derating above 40 °C. No derating means you can pack this breaker into a warm panel without recalculating the load. The operating range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
Physical fit and panel integration
Dimensions are 105 mm wide, 181 mm tall, and 86 mm deep — a standard 3-pole MCCB footprint that drops into most SENTRON distribution boards and panel-mount bases. The 105 mm width is the same as the 3VA2 family, so if you're swapping out an older 3VA2 or a 3VA1, the mounting holes and busbar connections should line up without re-drilling.
Communication and monitoring
This breaker includes a communication function — it can report status, current draw, and trip events over a bus system. That's useful for energy monitoring or remote troubleshooting. It does not have an undervoltage release or a trip indicator, so if you need those, you'd look at a different variant. The rated insulation voltage is 800 V, which covers most 400 V and 480 V installations with margin.