ELECTRIC POWER CONVERSION EQUIPMENT-NAMELY, ADJUSTABLE VOLTAGE MOTOR DRIVES, VARIABLE FREQUENCY CYCLOCONVERTERS, BATTERY CHARGERS, [ ELECTRO CHEMICAL POWER SUPPLIES, ] FREQUENCY CHANGERS, [ THYRISTOR AMPLIFIERS, ] PHASE CONTROLLED POWER RECTIFIERS FOR CONVERTING ALTERNATING VOLTAGE TO DIRECT VOLTAGE OF VARIABLE OR CONSTANT MAGNITUDE, AND LINE-VOLTAGE COMMUTATED INVERTERS