The PST Thyristor Power Units are two-phase thyristor power units designed for alternating-current resistance welding, specifically to control welding transformers in industrial welding systems.
The platform integrates control functionality and an integrated weld timer CPU in the power unit, with modular slots for a type-specific I/O interface, an optional fieldbus module for programming, and an optional retrofit quality module to support expanded control and monitoring functions. PST units are built for cabinet installation with an IP20 device rating and are intended to be installed in switchgear cubicles providing at least IP54 protection, with defined mounting clearances and forced-air or water-cooling requirements depending on the variant. The series is rated for 50/60 Hz supply operation in the 400–600 V class and is offered in versions sized by maximum transformer rating, such as air-cooled units for transformer capacities up to roughly 76 kVA and higher-capacity units up to roughly 250 kVA. Operational reliability is supported through integrated monitoring including temperature monitoring via a thermostatic switch that inhibits further welding sequences on overtemperature and guidance for sizing the unit using duty-cycle/load diagrams to avoid overload and thermal shutdown.
