Product Description:

The PSI61C0.751-L1 medium frequency inverter is manufactured by Bosch Rexroth Indramat as part of the PSI Frequency Inverters series. It converts three-phase supply power into high-frequency output suited for resistance welding guns, allowing accurate energy dosing and repeatable nugget formation. Integrated sequencing and fieldbus communication make the device a compact drive element for automated body-shop stations where controlled current pulses are required at every weld cycle.

The power section is sized for demanding welding duty. The inverter accepts an input of 400 - 480 VAC and draws a steady-state line current of 110 A. The output stage can supply up to 400 A for brief weld strokes without derating. Welding operations are timed at 1000 Hz sequence frequency, giving one millisecond resolution between successive spots. Internal logic runs from a dedicated 24 VDC control supply, isolating process electronics from power disturbances. Production cells exchange commands and status through the PROFINET/IO interface, while an Ethernet-based timer aligns the 144 serial inputs with the 144 serial outputs. This architecture supports as many as 1024 weld programs that can be recalled by the higher-level controller.

Thermal performance depends on efficient air movement. Cabinet electronics dissipate 69 W under nominal load, and total cooling losses can reach 360 W at maximum duty. The design remains functional up to 55 °C ambient, with an enclosure rating of IP20, so filtered cabinet air is sufficient. When paired with a PSG3100 transformer, the inverter can deliver secondary peaks of 20 kA, providing the headroom needed for thick sheet assemblies. Power terminals accept conductors up to 50 mm², while auxiliary wiring falls within a 35 mm² range, matching common industrial cable sets.