Power system for a high-power burst mode pulsed load

A novel power system, recently completed and commissioned, is described. Operating directly from an ll-kV, 50-Hz public supply, it provides the electrical energy for a burst mode, pulsed load. In each burst, the minimum energy delivered by the power system is 100 kJ at a rate of 330 kW. The pulse modulator operates at a peak charge of 105 kV and is capable of switching 200 MW over a range of pulse lengths and repetition rates. The high-voltage, high-current thyratrons used as the charge, discharge, and PFN energy dump switches were specially developed, four-gap, double-ended CX 1199B thyratrons. Supply voltage stepup transformers were designed to operate over bursts of variable pulse number, length, and rate, with the rectified unfiltered transformer output directly feeding the modulator charging circuit at up to 65 kV. Polarizing effects in the transformer core caused by the use of repetition rates equal to, or harmonically related to, the supply frequency were analyzed and effectively eliminated. Special winding techniques were developed to provide the strength and insulation for withstanding fault transients. While the power supply is capable of limiting fault currents occurring in the modulator and load, normal full system protection is provided by PFN energy dumping and, in the ac supply, by fast-acting vacuum contactors. Comprehensive control, monitoring, and mode selection are based on micrologic elements. By using direct, high-voltage modulation considerable flexibility is possible. The various alternative arrangements which derive from this design concept are explained. In addition, factors which determined the major features of the equipment are reviewed. The construction, layout, and performance are illustrated.