Product Description:

The PST6250.323-L is a thyristor power unit manufactured by Bosch Rexroth Indramat within the PST Thyristor Power Units series. Installed in automation cabinets, it functions as a solid-state switch that modulates high current sent to welding or heating transformers, providing fast and repeatable power control that mechanical contactors cannot achieve. The design targets installations where reliable phase-angle or burst-firing control must be integrated into a distributed plant network without adding excessive thermal load to adjacent equipment.

In service, the unit conducts a continuous thermal current of 200 A, enabling it to supply transformers rated up to 250 kVA while staying within its heat sink limits. A maximum duty cycle of 50% applies, so the gating strategy must leave equal off-time for heat dissipation during cyclic operation. The trigger electronics are energized by a 24 V DC control supply that can be sourced from common cabinet auxiliaries, and overvoltage protection is handled by an MOV network that clamps incoming surges. The enclosure has an IP20 rating, indicating finger-safe construction for mounting inside closed switchgear panels. Synchronization with higher-level controls is provided by the built-in INTERBUS timer interface, allowing precise firing-angle commands from a PLC.

The assembly is air cooled, so cabinet airflow must remain below 45 °C to keep internal heat sink temperatures stable, even when the surrounding ambient reaches 55 °C. Recessed mounting with M6 hardware secures the chassis while maintaining clearance for access. Line terminals accept conductors up to 95 mm², supporting low-loss connections at full load, and typical switchgear cabinet dissipation is limited to 70 W, which helps simplify thermal management in compact enclosures. Integrated temperature monitoring disables gate pulses if heat sink thresholds are exceeded, preserving device integrity and preventing unplanned shutdowns.