Microcontroller based Governor MEG-601 uses state-of-the-art technology, for controlling Diesel Engine of Diesel Electric Locomotives. This is a maintenance free alternative to the hydraulic Woodward Governors popularly used for this application. The Governor consists of a Control Unit mounted in the Driver cab, and an Actuator Unit mounted on the Engine. The Actuator Unit can be mounted exactly on the same Engine base as Woodward Governors. The Governor controls the engine speed, based on throttle handle position (popularly known as notch) selected by the Driver on the Driver Desk. Engine RPM is measured from a Tachogenerator or speed sensor mounted on the Engine. Digital PID control is used to calculate desired fuel rack position dynamically, based on the selected notch on throttle handle and measured Engine RPM. A Stepper motor drive is used in the Actuator Unit to control the fuel rack of Diesel Engine. The Governor also controls load on the engine electrically, so as to limit horsepower at each notch to a preset level, through an electrical interface with the excitation system of Locomotive. Booster (Turbo) air pressure is measured through a pressure sensor mounted in the air manifold. Movement of fuel rack is limited as a function of this pressure so as to prevent incomplete combustion of fuel, black smoke, excessive engine temperature, fuel wastage etc caused by lack of air to burn the fuel. Lube oil pressure is continuously monitored and Engine is shutdown if the lube oil pressure is less than the specified pressure at each notch position. This protects the Engine from damage due to malfunction of lube oil pump etc.

More than 500 units have been installed on Diesel Electric Locomotives of various designs on Indian Railways. Indian Railways currently fits Microcontroller based Governors on all new and retrofit Diesel Locomotives. Apart from new built Locomotives, Indian Railways have taken up a healthy retrofit program to upgrade more than 200 locomotives per year with Microcontroller based Governors. Medha is a market leader in these systems with over 99% market share. Medha's Governor has  and can be installed in place of an existing Governor.