Product Description:

The PSI63C0.781-W1 from Bosch Rexroth Indramat belongs to the PSI Frequency Inverters series and is a medium-frequency inverter used in resistance-welding cells and other high-current applications in automated production. The device converts three-phase mains power into a regulated medium-frequency output that a welding transformer uses to deliver precise heat during short duty cycles. In an automation line, it serves as the power stage between a PLC and the welding electrodes, synchronizing current pulses with machine motion. This arrangement supports repeatable weld timing where current delivery must track the sequence of clamping and electrode contact.

The inverter connects to mains supplies rated at 400 – 480 VAC and draws a nominal 110 A, so upstream protection must be sized for the electrical demand. Its water-cooled construction removes internal heat through a closed loop, and a minimum flow of 4 l/min with a pressure drop of 0.1 bar keeps turbulence across the cold plate. Under maximum load, the electronics add 110 W of cabinet heat loss while the switch cabinet baseline adds 69 W, which helps determine enclosure cooling requirements. Communication is carried over Ethernet, and an integrated network timer can trigger welding shots that reach a peak of 36 kA.

Inside the inverter, a TriCore processor coordinates current regulation loops in microseconds for the fast response needed during welding pulses. To support spot-weld clamps, the primary side can deliver up to 800 A, and the heat removed from the coolant path is limited to 360 W to keep outlet temperatures within plant water requirements. The unit mounts vertically, and its face width of 239 mm, depth of 280 mm, and height of 448 mm allow direct placement on 19-inch rack rails, while power cabling must be at least 35 mm² to handle repetitive pulses.