Electronic Governor is a maintenance free alternative to the mechanical 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 mechanical 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, to limit horsepower at each notch to a pre-set 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 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.

Vigilance Control Device (VCD) is a microcontroller based safety device which will automatically apply penalty brakes in case the driver is incapacitated. Similar operation is available in older locomotives in the form of Deadman’s Lever.

Operating Principle

Installed on locomotive, VCD gives cyclic warning to the driver. Based on drivers reaction to this warning (in terms of any of the pre-defined sets of actions to be done by the driver), the system automatically resets the alerting cycle. In case, the driver fails to acknowledge the initial alert signals, a set of additional alert indications are given. Even failing to respond to these additional alert signals also will result in automatic application of penalty brakes.

Medha is one of the leading manufacturers of Speed Recorders for Railway applications. These recorders are used on Locomotives and are similar in function to Black boxes in aeroplanes. Speed Recorders are used for monitoring the performance of Loco Driver and especially in the event of an accident the recorded data becomes vital for establishing the cause of accident.

Medha supplies driver consoles in ready to install condition with TFT LCD displays, master controller, brake controller, electrical switches, gauges, lamp indications and other required components and sub-assemblies. Modular panels are used for easy changes/modifications including provisions for future additions.

Driver's display console for Locomotives / EMUs / Metro Cars for showing running data (status information), historical data (Event / Fault logs), maintenance related data and for data entry.

Medha supplies PA/PIS system and LED display boards for trains and coaches Audio system is designed so that the passengers receive relevant information at appropriate times LED displays are customized using different LED sizes, spacing between LEDs, colors (multi/mono), matrix size, mounting requirements etc. LCD display boards are also available as per customers requirements and specifications.

Vehicle remote monitoring solution is an Internet based system connecting all locomotives in the field with centralized Locomotive Management System through CDMA and / or GSM network communication. This solution consists of:

Railways world-over can increase throughput by running longer freight trains which require more motive power. More locomotives when bunched together cause unacceptably high coupler forces. This situation can be overcome by distributing locomotives throughout the consist of the train, which will require a means of synchronizing actions on all locomotives based on driver inputs in the lead locomotive.

Medha's Distributed Power Control (DPC) system, when installed can provide real-time communication between lead and remote locomotives through wireless data radio to synchronize all locomotives in the train. Additional benefits are achieved by applying brakes simultaneously from all locomotives, reducing the braking distances.

Medha offers HEP units from 300kVA-500kVA and higher (1000kVA – 2x500kVA), utilizing capacities of alternator / transformer to meet auxiliary power requirements such as lighting, fans, HVAC, heating, battery charging etc. of complete train. HEPs are IGBT based converters, using sine filters at inverter output to minimize harmonic distortions. Protections for output overload, short circuit and power ground are provided. The converters are designed to suit wide range of inputs.

Both Diesel and Electric locomotives use DC auxiliary power supply and small DC motor used for various applications. These DC machines are failure prone (many times leading to failure of complete locomotive) and hence need more maintenance. To increase the reliability of these motors, Medha has developed 3phase AC motor with inbuilt inverter, so that they can directly replace existing DC motors in use. These replacement motors are compatible with input DC voltage and are within the physical space constraints.