A.-c. switch speed control system for a.-c. motors

Claim 1

IN A DEVICE FOR CONTROLLING THE SPEED OF MOTORS OF THE INDUCTION AND SYNCHRONOUS TYPES, THE COMBINATION OF: A SOURCE OF AN A.-C. POTENTIAL; A PAIR OF INPUT TERMINALS TO WHICH SAID A.-C. POTENTIAL IS APPLIED; A FIRST SILICON CONTROLLED RECTIFIER HAVING AN ANODE, A CATHODE, AND A GATE ELECTRODE; A SECOND SILICON CONTROLLED RECTIFIER HAVING AN ANODE, A CATHODE, AND A GATE ELECTRODE; MEANS CONNECTING THE FIRST SILICON CONTROLLED RECTIFIER ANODE AND THE SECOND SILICON CONTROLLED RECTIFIER CATHODE TO ONE OF THE A.-C. INPUT TERMINALS; MEANS CONNECTING THE FIRST SILICON CONTROLLED RECTIFIER CATHODE AND THE SECOND SILICON CONTROLLED RECTIFIER ANODE TO THE MOTOR; A FIRST TRANSFORMER HAVING A PRIMARY WINDING AND A SECONDARY WINDING; MEANS CONNECTING THE FIRST TRANSFORMER PRIMARY WINDING ACROSS THE SOURCE OF A.-C. POTENTIAL; A FIRST POTENTIOMETER HAVING AN OUTPUT TERMINAL; MEANS CONNECTING THE POTENTIOMETER IN PARALLEL WITH THE FIRST TRANSFORMER SECONDARY WINDING; MEANS CONNECTING THE FIRST POTENTIOMETER OUTPUT TERMINAL TO THE FIRST SILICON CONTROLLED RECTIFIER GATE ELECTRODE; A SECOND TRANSFORMER HAVING A PRIMARY WINDING AND A SECONDARY WINDING; MEANS CONNECTING THE SECOND TRANSFORMER PRIMARY WINDING ACROSS THE MOTOR BETWEEN THE A.-C. POTENTIAL SOURCE AND THE FIRST SILICON CONTROLLED RECTIFIER CATHODE; A SECOND POTENTIOMETER HAVING AN OUTPUT ARM; MEANS CONNECTING THE SECOND POTENTIOMETER ACROSS THE SECOND TRANSFORMER SECONDARY WINDING AND TO THE SECOND SILICON CONTROLLED RECTIFIER CATHODE; MEANS CONNECTING THE SECOND POTENTIOMETER OUTPUT ARM TO THE SECOND SILICON CONTROLLED RECTIFIER GATE ELECTRODE; A SATURABLE REACTOR HAVING A REACTANCE WINDING AND A CONTROL WINDING; MEANS CONNECTING THE SATURABLE REACTOR REACTANCE WINDING ACROSS THE FIRST TRANSFORMER SECONDARY WINDING; AND MEANS FOR PERIODICALLY PASSING A CONTROL CURRENT THROUGH THE SATURABLE REACTOR CONTROL WINDING TO CYCLICALLY SATURATE FOR A SELECTED VARIABLE PERIOD SAID SATURABLE REACTOR.