The motors used are induction or asynchronous motors designed to have characteristics suitable for traction. The speed and torque of the motor are controlled by varying the frequency, voltage and current applied to the stator coils. Motors for a typical locomotive would be in the range 400 to 600 kW.
Why induction motor is used in traction?
This is the most important feature of traction motor provides opportunity for saving on energy but also smoothness in braking, saving on wear and tear in mechanical braking system. An Induction motor works as a generator if mechanical speed is more than the synchronous speed.12 мая 2013 г.
What is traction motor control?
A speed control system of traction motors for electric vehicles comprises a traction motor for causing an electric vehicle to run, a D.C. supply source for supplying voltage to the traction motor, a chopper for chopping the voltage fed from the D.C. supply source to the motor, and a chopper control circuit for …
Why is DC series motor used in traction?
DC series motor has been the most used solution for the traction of locomotives, trolleybuses, trams and others, characterized by a speed and torque control using additional resistances, which means a low efficiency, electromechanical contactors, high maintenance costs, dynamic braking in resistances.
Are locomotives AC or DC?
Depending on the design of the train, it can either produce AC or DC current using a generator powered by the diesel engine. Because of various electrical connections, multiple locomotives can be operated by a single lead until operated by a single crew.
Which motor is used in metro train?
What is the need for traction motor control?
The control of traction motors for starting and for smooth acceleration is very much essential to avoid damage to the motors. The control equipment is provided for manual and automatic operation. Usually a master controller is used for the purpose.19 мая 2017 г.
How do traction motors work?
The DC motor works because, simply put, when a current is passed through the motor circuit, there is a reaction between the current in the field and the current in the armature which causes the armature to turn. The armature and the field are connected in series and the whole motor is referred to as “series wound”.
What is traction inverter?
Traction inverters convert dc power from an on-board high voltage (HV) battery into ac power to drive the main motor or motors of an electric vehicle. In addition, traction inverters perform functions such as voltage boosting, switch protection and regenerative braking.
What type of DC motor is used in traction?
Traditionally, these were series-wound brushed DC motors, usually running on approximately 600 volts. The availability of high-powered semiconductors (thyristors and the IGBT) has now made practical the use of much simpler, higher-reliability AC induction motors known as asynchronous traction motors.
Which DC motor is used in tramways?
This paper compares five different motor types used in variable speed drives: a dc motor with a mechanical commutator and with electromagnetic or permanent magnets excitation, a cage induction motor, asynchronous cascade with a slip‐ring motor and a brushless motor with PM excitation.
Are diesel locomotives AC or DC?
In a diesel–electric locomotive, the diesel engine drives either an electrical DC generator (generally, less than 3,000 horsepower (2,200 kW) net for traction), or an electrical AC alternator-rectifier (generally 3,000 horsepower (2,200 kW) net or more for traction), the output of which provides power to the traction …
Why train engines are not turned off?
Another reason for not turning off diesel train engines, lies in the engine itself. … It is also interesting to know that while diesel locomotives are idling, fuel consumption is more than when the train is moving. This is because, while idling, the batteries are being charged, and the air compression is in operation.
What is more efficient AC or DC?
1. DC power is significantly more energy efficient than AC power. DC motors and appliances have higher efficiency and power to size characteristics. … The greater efficiency resulting from recent developments in DC converter technology allows improvements in electricity delivery over long distances.
Which current is used in railway?