What this breaker is and what the ratings mean for fit
The Siemens 3VA1110-5GE42-0AA0-ZD00 is a 4-pole IEC frame 160 molded-case circuit breaker with a TM220 thermal-magnetic trip unit set at In=100A, overload adjustable Ir=70A..100A, and instantaneous short-circuit pickup Ii=10 x In. The breaking capacity class M gives Icu=55kA at 415 V AC — that is the maximum fault current it can safely interrupt without damage. For a 100A feeder, 55kA SCCR at 415V provides generous headroom for most industrial distribution panels, meaning selectivity coordination with downstream breakers is easier to achieve. The ATFM designation indicates a fixed thermal-magnetic trip with adjustable thermal (Ir) and fixed magnetic (Ii). The N-conductor protection is set to 100%, so the neutral pole is fully rated — important for systems where neutral current can approach phase current, such as in nonlinear loads or 4-wire distribution. The nut keeper kit and DC Power OEM in China note suggest this variant is configured for a specific OEM assembly — the nut keeper secures the breaker in a panel or enclosure where vibration or repeated access could loosen standard mounting. If you are replacing an existing unit in a DC Power OEM cabinet, this is the exact fit.