S SPANG POWER CONTROL

ELECTRICAL POWER CONVERSION AND CONTROL SYSTEMS AND EQUIPMENT-NAMELY, POWER REGULATORS, INVERTERS, CONVERTERS, FREQUENCY MODIFIERS, REGULATED POWER SUPPLIES, TRANSFORMERS, AND SATURABLE REACTORS; TRANSDUCTORS, MAGNETOMETERS, AND MAGNETIC MEASURING INSTRUMENTATION-NAMELY, SHUNT AMPLIFIERS AND D.C. CURRENT TRANSFORMERS