As a result, the DF200's total transportation time was reduced by more than 30 minutes per 300 km due to its faster acceleration and top speed.
(3) Equipment
* Diesel engine
Two identical MTU model 12V396TE14 diesel engines are used in one locomotive. This type of diesel engine is relatively lightweight and compact as long as the system is designed and operated within the specified rotational speed and output power. The engine is a water-cooled, four-stroke, twelve-cylinder V-type. It has direct fuel injection, an inter-cooler and two exhaust superchargers. Its maximum output power is rated at 1250 kW at 1800 rpm. The speed control system is based on an electronic governor with microprocessors, which ensures accurate rotational speed and alternator output voltage, in accordance with the notch command.
* Alternator
The alternator is a brushless synchronous unit with a cylindrical rotor. The field exciting current flows through rotor windings from the separated exciter, which is excited from outside the unit, coupled to the rotor axle. The unit is air cooled with self ventilation, and directly coupled to the diesel engine by a Geisslinger elastic joint.
* Main converter
There are two identical converter containers in the locomotive. Inside the container, there are three identical PWM inverter circuits corresponding to three traction motors and one additional three-phase diode bridge rectifier circuit for AC to DC conversion. There are also four microprocessor control units, three of which are for controlling inverters and one for alternator exciter control.
The main switching semiconductor devices are 4.5 kV, 1.5 kA GTO thyristors. They are efficiently cooled by the heat pipe method with forced air ventilation. One cooling unit consists of two GTO thyristors with snubber components, two free wheeling diodes, two gate driving units, capacitors for DC voltage stabilization and a heat pipe cooling device.
* Traction motor
The traction motor is a cage-type three-phase induction unit with a rated output of 320 kW. Every motor is cooled by forced ventilation.
* Auxiliary power supply
The auxiliary power supply is also a three-phase GTO thyristor inverter similar to the traction converter, with a rated output of 170 kVA. The configuration of the semiconductor devices and cooling unit is almost the same as those of the traction converter. However, output frequency and voltage are controlled to remain constant.
