Starting device for direct current motors

Claim 1

A STARTING DEVICE FOR A DIRECT CURRENT MOTOR COMPRISING A DIRECT CURRENT MOTOR HAVING AN ARMATURE AND A SERIES FIELD WINDING JOINED AT A FIRST JUNCTION POINT; A STARTING RESISTOR CONNECTED IN SERIES WITH SAID FIELD WINDING; A PLURALITY OF CONTROL RESISTOR BRANCHES, EACH BRANCH INCLUDING A CONTROL RESISTOR, A JUNCTION POINT AND A CONTROLLED RECTIFIER ELEMENT, SAID BRANCHES BEING CONNECTED IN PARALLEL WITH SAID STARTING RESISTOR SO THAT BY A FIRST SEQUENTIAL ENABLING OF THE CONTROLLED RECTIFIER ELEMENTS, SAID CONTROL RESISTORS BECOME SEQUENTIALLY ELECTRICALLY CONNECTED IN PARALLEL WITH SAID STARTING RESISTOR TO PROGRESSIVELY REDUCE THE RESULTANT RESISTANCE VALUE THEREOF; A FIRST CONTACTOR FOR SHORT CIRCUITING SAID STARTING RESISTOR AFTER ALL OF SAID CONTROL RESISTORS ARE ELECTRICALLY CONNECTED IN PARALLEL WITH SAID STARTING RESISTOR; A SECOND CONTACTOR, ONE END OF WHICH IS CONNECTED TO THE FIRST JUNCTION POINT; PLURALITY OF FIELD SHUNTING RESISTORS, EACH BEING CONNECTED BETWEEN THE OTHER END OF SAID SECOND CONTACTOR AND ONE OF SAID SECOND JUNCTION POINTS IN ONE OF SAID BRANCHES, AND, A RECTIFIER ELEMENT BETWEEN EACH OF SAID SECOND JUNCTION POINTS AND THE CORRESPONDING FIELD SHUNTING RESISTOR, SAID FIELD SHUNTING RESISTORS BEING ELECTRICALLY CONNECTED ALL AT ONE TIME IN PARALLEL WITH SAID FIELD WINDING THROUGH THE CORRESPONDING CONTROL RESISTOR WHEN SAID SECOND CONTACTOR IS SHORT CIRCUITED, AND ARE THEN SEQUENTIALLY ELECTRICALLY CONNECTED IN PARALLEL WITH SAID FIELD WINDING TO BYPASS THE ARMATURE CURRENT AROUND THE FIELD WINDING TO WEAKEN THE MAGNETIC FIELD INTENSITY BY A SECOND SEQUENTIAL ENABLING OF SAID CONTROLLED RECTIFIER ELEMENTS, SAID CONTROLLED RECTIFIERS BEING USED BOTH FOR REDUCING THE RESULTANT RESISTANCE VALUE OF THE STARTING RESISTOR AND WEAKENING THE MAGNETIC FIELD INTENSITY OF THE FIELD WINDING.