Product Description:

The PST6100.680-L thyristor power unit is manufactured by Bosch Rexroth Indramat and belongs to the PST Thyristor Power Units series. This solid-state assembly regulates current to resistance-welding transformers and other intermittent loads, giving precise power control inside automated production cells. By switching pairs of SCRs in a two-phase configuration, the unit modulates the primary side of medium-frequency transformers, enabling repeatable heat profiles while remaining compact enough for IP20 control cabinets. This control method helps maintain consistent weld energy during repeated production cycles.

It is designed for cabinet environments where a maximum power dissipation of 70 W must be removed by forced airflow, so the module uses an air-cooled heat sink and is limited to inlet temperatures of 45 °C. With a continuous output of 110 A, it can drive the secondary currents demanded by mid-range welding heads while matching a transformer capacity of 76 kVA. The firing circuit synchronizes to mains at 50/60 Hz, allowing installation in international plants. An enclosure rating of IP20 indicates finger-safe terminals but no liquid sealing. Air turbulence and device stress are monitored by integrated temperature sensors, and metal-oxide varistors provide overvoltage suppression on the incoming two-phase supply.

For cyclical applications, the power stage operates at a 50% duty cycle under defined thermal limits. Operation is permitted up to 2000 m altitude without current derating, making the unit suitable for elevated production sites. Power connections accept copper conductors up to 50 mm², simplifying low-impedance links to bus strips. Control electronics use a 24 V DC logic supply and exchange timing commands through the DeviceNet interface to coordinate weld impulses with robot motion. This communication method supports synchronized operation without separate analog timing lines.