Supercomputers, fishing for information

All 370's ran off 415 Hz 3-phase power. The mid-sized ones had the motor-generator set built into the back of the machine. The 415 Hz (regulated) power was transformed to low voltage and run through an inductor-input filter and then series pass regulated. They had a circuit they called an "electronic capacitor" that pulled extra current through the inductor during the voltage peaks, so the inductor carried enough current during the voltage valleys. This reduced the ripple current on the capacitor banks. The 360s ran off single-phase 120 V 2500 Hz power, produced by a "converter-inverter" unit in the back, that converted utility 3-phase power to DC, then inverted it with an SCR inverter. This made the DC power supplies in the machine quite small. Since they ran off regulated 2500 Hz power, they dropped only a very small voltage across the series-pass transistor. Jon