Inverter Action on Reversing of Thyratron Motor Control

Thyratron control of d-c motors offers a fast and smooth braking or reversal which is finding wider application in industry as the characteristics become better known. With proper control the rectifier circuit, which normally supplies power to the armature of the motor, can be operated as an inverter to decelerate the motor by regenerating the rotational energy of the motor and its load into the a-c system. The circuit then shifts to rectifier operation to accelerate the motor and load to the preset speed in the reverse direction. The motor-armature current can be held very nearly constant over the full reversal operation of deceleration and acceleration at a value which can be made less than the rated motor current. Test results and theory show that the motor´s inherent reactance is sufficient for inverter operation, and, that during normal inversion, commutation of the tubes is not difficult. In addition, inversion can be utilized to bring the motor to a stop more efficiently than by plugging and more rapidly and efficiently than by dynamic braking.