What it is and what it does
This Siemens 3VA1140-5GF42-0AA0-ZD00 is a 4-pole IEC frame 160 molded case circuit breaker with a 40 A thermal-magnetic trip unit (TM240). Its breaking capacity class M delivers an Icu of 55 kA at 415 V, which means it can safely interrupt a fault current of that magnitude without welding its contacts or rupturing the case — essential for high-fault panels downstream of large transformers or parallel-fed busways.
Overload and short-circuit settings
The TM240 trip gives you an adjustable overload protection band (Ir) from 28 A to 40 A, so you dial it in to the exact continuous load of the feeder — no need to swap breaker frames for a small load change. Short-circuit pickup (Ii) is fixed at 5 to 10 times In (200 A to 400 A), which keeps the breaker selective with downstream branch devices while still clearing hard faults fast. The nut keeper kit on this variant secures the breaker in a DC Power OEM cabinet built in China; the 100% N conductor protection means the neutral pole is switched and protected identically to the phase poles, critical for 4-wire systems where an open neutral can float voltages.