What it is and what the ratings mean for fit
The Siemens 3VA2040-8HN36-0AA0 is a SENTRON molded case circuit breaker (MCCB) with a 40 A continuous current rating, three poles, and an ETU350 electronic trip unit. The 40 A rating is the full-load current it carries continuously at ambient temperatures from 40 °C up to 70 °C without derating — so it holds steady in a warm cabinet where a thermal-magnetic breaker might need to be oversized. The ETU350 is an adjustable electronic trip unit that gives selectivity tuning for coordination studies, which is the main reason to choose this over a fixed-trip MCCB. Breaking capacity is 330 kA at 415 V, meaning it can safely interrupt a fault current up to that level on a 400 V-class distribution system without upstream fuses or a current-limiting reactor. At 690 V the rating drops to 52.5 kA — still high enough for most industrial secondary feeders. Rated insulation voltage is 800 V, so the breaker is suitable for 690 V line-to-line systems with margin. The IP40 front protection means the breaker face is protected against solid objects over 1 mm, but not sealed against moisture — standard for indoor panel mounting.
Panel integration and dimensions
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep. The 105 mm width is the standard 3-pole MCCB footprint for the 3VA2 frame — it occupies the same panel cutout as other 3VA2 breakers, so swapping between ratings within the frame size requires no re-drilling. Depth of 86 mm includes the handle and terminal covers; allow clearance for cable bending radius below the line and load lugs.