Switch disconnector in MCCB design — 125 A, no overload protection
The Siemens 3VA1112-1AA36-0CH0 is a SENTRON 3VA1 switch disconnector in MCCB design, rated 125 A continuous across the full operating temperature range from 40 °C to 70 °C — no derating needed up to that ceiling. Three poles, front terminal clamp connection, and an insulation voltage of 800 V make it suitable for panel-mounted isolation up to 690 V AC or 500 V DC. This is a pure disconnector — no overload or short-circuit protection built in. The 125 A rating holds flat from 40 °C through 70 °C, which simplifies panel thermal budgeting: you don't have to recalculate for elevated ambient conditions within that band.
Undervoltage release and auxiliary switch complement
Factory-fitted with an undervoltage release (UVR) rated 120–127 V AC 50/60 Hz. The UVR trips the disconnector when control voltage drops below the dropout threshold — standard for safety isolation in machine control circuits. Two auxiliary switches HQ and one trip alarm switch HQ provide status feedback; the HQ designation indicates high switching reliability for signal integrity. The auxiliary contact block carries three CO contacts. No communication function or leading-contact UVR option on this variant. If motor-drive remote operation is needed later, the product extension supports an optional motor drive.
Dimensions, mounting, and environmental limits
Width 76.2 mm, height 130 mm, depth 70 mm. Front terminal connection accepts clamp-type conductors for the main current circuit. IP40 on the front face — suitable for enclosed panel mounting where no water ingress is expected. Operating temperature range -25 °C to 70 °C; storage from -40 °C to 80 °C. Maximum power loss 38 W.