Magnet Current Bypass Shunt

A precision active shunt has been developed for fine tuning of individual magnet fields in a series magnet string operated from a single power supply. The shunt uses power transistors operated in linear mode to regulate the bypass current in the range 0 to 50 A with precision of ±10 mA. Communication with and control of shunt which may be floating 1000 V or more above earth ground, is by means of transformer coupled isolation amplifiers. Because of reliability requirements, 7 transistors, mounted on demountable water cooled copper plate are used. Low level electronics and current sensing resistor are mounted on the same plate. This paper presents system description and preliminary results.