The Siemens SENTRON 3VA1112-1AA42-0AH0 is a 4-pole switch disconnector rated at 125 A continuous current (Iu) in an IEC frame 160 package. This is a load-break disconnect, not a circuit breaker — it has no overload or short-circuit protection elements built in. It is designed for manual isolation and switching of circuits where overcurrent protection is handled upstream or by a separate device. Rated operational voltage goes up to 690 V AC 50/60 Hz and 600 V DC, with an insulation voltage (Ui) of 800 V.
What the ratings mean for fit
The 125 A rating is the uninterrupted current the disconnector can carry continuously without exceeding a 38 W maximum power loss. That 38 W is the heat you need to manage inside the enclosure — at 125 A steady load, the switch will dissipate that much. The IP40 front protection means it is suitable for dry indoor panels; it keeps tools and fingers out but is not rated for washdown or outdoor exposure. The 4-pole configuration (switching all three phases plus neutral) is typical for TN or TT systems where the neutral must be isolated when the disconnect is open.
Integration and mounting
The disconnector measures 70 mm deep, 101.6 mm wide, and 130 mm high. Main circuit connections are via front-facing busbar terminals — the busbar connection type means it is designed to bolt directly onto a busbar system inside the panel, not to accept lugged cables. The auxiliary contact configuration is 2 auxiliary switches plus 1 trip alarm switch, all HQ (high-qualified) type, giving three CO contacts total. A nut keeper kit is included for the busbar mounting hardware.
The closest peer in the SENTRON family is the 3VA2116-5HL32-0AK0, a 3-pole molded case circuit breaker rated at 160 A with an ETU320 electronic trip unit. That part provides both overload and short-circuit protection (LI characteristic) and has a higher interrupting capacity — up to 187 kA at 240 V. The 3VA1112-1AA42-0AH0, by contrast, is a switch disconnector with no trip unit and no overcurrent protection. It is the correct choice when the protective function is already covered upstream and only a visible-break isolation switch is needed. It will not drop into a panel designed for the 3VA2116 without rewiring: the 3VA1112 is 4-pole versus the 3VA2116's 3-pole, and the busbar connection arrangement differs.