Product Description:

The PST6250.255-L is a thyristor power unit manufactured by Bosch Rexroth Indramat for the PST Thyristor Power Units series. It modulates high-current AC lines in industrial automation so that heating zones, rectifier stages, and other power-intensive loads receive controlled energy. By combining triggering electronics and power semiconductors in one recessed assembly, the device provides a compact interface between a control system and the main transformer bank without requiring additional active cooling hardware. This type of power section is suited to applications where large electrical loads must be regulated smoothly instead of being switched only fully on or fully off.

The unit operates from a control supply of 24 V DC, and its thyristor stack carries a nominal system current of 200 A. It can feed transformers rated up to 250 kVA while limiting cabinet heat loss to 70 W. The enclosure has an IP20 rating for touch-safe panel installation, and operation is permitted at ambient temperatures up to 55 °C. The unit is air cooled, so heat is removed by convection across the heat sinks, and Class F insulation supports use in moist airflow at installation altitudes up to 2000 m. Its recessed mounting style lets the chassis sit flush with panel cutouts while keeping the power connections accessible inside the cabinet.

For intermittent processes, the device allows a maximum duty cycle of 50% when incoming cooling air remains below 45 °C. Screw terminals accept conductors up to 95 mm², and the housing weighs 12.5 kg for panel mounting. Overvoltage is limited by an MOV network, which helps protect the thyristor stage during line disturbances. Control links can be established through parallel, serial, or fieldbus channels, giving the unit flexibility in different control architectures. The internal timer is preset for PROFIBUS communication so firing-angle control can be coordinated with the PLC cycle.