Abstract: A control system and method for controlling the speed of a PSC motor having an auxiliary winding configured to provide torque for initial motor startup and a run winding configured to provide continuous motor operation. The motor is coupled to a capacitor configured to direct a portion of a current through the run winding when the PSC motor reaches its intended speed. The control system includes a speed control unit coupled between a voltage line and the PSC motor and a bypass circuit coupled between the voltage line and the capacitor via a first path. The speed control unit is configured to variably control the speed of the PSC motor. The bypass circuit is configured to receive a control signal from the speed control unit via a second path and to regulate a chopped voltage wave form generated by the speed control unit such that at least a portion of the chopped voltage wave form is not applied to the capacitor.

Abstract: In the construction of a plug-type, coke oven door, which plug is fitted with an integral flue or duct for venting of gases, the front and side walls of the plug are constructed so as to provide sufficient thermal conductivity, whereby heat entering the duct, primarily by conduction through the front wall, may readily be transferred to the left and right side walls thereof so as to maintain a desirable high temperature boh within the duct and at the exterior surfaces of the side walls to prevent or significantly decrease carbon accumulation.