Product Description:

The PST625-EW thyristor power unit is manufactured by Bosch Rexroth Indramat as part of the PST Thyristor Power Units series. It uses a two-phase thyristor design with water cooling and is installed between a grounded industrial power bus and a step-down transformer to regulate current through phase-angle control. This arrangement lets the module deliver repeatable electrical pulses for automated welding or heating processes that require closely controlled energy delivery. With a mass of 9.1 kg, the unit is intended for cabinet-mounted systems where stable power regulation and compact integration are important.

Power conductors connect through a terminal that accepts up to 95 mm², helping reduce resistive loss at the supply connection. Under rated conditions, the silicon stack carries a nominal line current of 230 Arms, and the primary circuit can reach 400 A for short bursts. Control circuitry limits conduction to a maximum of 50 %, while a regulated +24 VDC logic rail powers the gate drivers and digital electronics. Sixteen discrete inputs handle enable, trigger, and parameter selection signals, and twelve discrete outputs return ready, fault, and cycle-complete status signals to the higher-level controller.

Program storage inside the controller holds 64 machine programs, and it also includes 8 manual weld programs for quick setup changes. During production, the controller maintains an output duty cycle of 30 % to keep average power within the thermal range of connected tooling. The power unit is matched with transformers up to 155 kVA, making it suitable for medium-capacity resistance welding or heating applications. Its enclosure is rated IP20, so it helps prevent accidental finger contact while still requiring installation inside a protected electrical panel on TN or TT grounded networks.