What the 40 A AC-1 rating means for fit
The 3RF3340-3AA06 is a 1-pole SIRIUS 3RF33 solid-state contactor rated 40 A in AC-1 duty at 40 °C — that's the resistive load curve, so it handles heaters, lighting banks, and transformer primaries up to that current. The 48-600 V switching range covers common low-voltage line supplies across global sites. Control is 24 V DC, which is standard for PLC-driven panels and safety circuits.
Packaged individually, dimensions 105 x 27 x 122 mm — fits a standard DIN-rail footprint with 27 mm width, leaving room for adjacent contactors or overload relays in the same row. Ring cable lug connection means the power terminals accept ring terminals, not fork or pin; factor that into your wire-prep step. The 1-pole construction switches one phase; for three-phase loads you stack three units or use a 3-pole variant.