3. AC Series Motor: Many single phase ac motors have been developed for traction purposes but only compensated series type commutator motor is found to be best suited for traction. Single phase induction motors have been abandoned as they are not capable of developing high starting torque.
Which type of DC motor is used for electric traction?
The synchronous motor has been used in electric traction – the most well-known application being by the French in their TGV Atlantique train. This used a 25 kV AC supply, rectified to DC and then inverted back to AC for supply to the motor.
Why is dc series motor is suitable for 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.
Why induction motor is used in traction?
An Induction motor works as a generator if mechanical speed is more than the synchronous speed. … Maximum value o regenerative tractive effort is limited to 25T and so is negative torque of the traction motor.
Which traction system has high efficiency?
The electric traction system is the most efficient of all other traction system such as steam and internal combustion (IC) engine type systems.
Are locomotives AC or DC?
Modern AC locomotives tend to have better traction and offer better adhesive to the tracks than earlier models. AC diesel-electric trains are most commonly used for carrying heavier loads. However, DC diesel-electric trains are still very popular as they are relatively cheaper to manufacture.
Which motor is most suitable for electric traction work?
Explanation: DC motors are used for traction as, according to the characteristics of DC motors speed is inversely proportional to torque and square of armature current as well, if linear magnetization is concerned. Thus, DC motors are perfectly suitable for traction.
Which motor is used for high torque?
Series wound DC motors are best for applications that require high startup torque, without the need for speed regulation. Like a shunt motor, as a load is applied to a DC series motor, the motor speed decreases, which reduces the back EMF and increases the net voltage.
Why the DC motors are preferred over AC motor?
DC motors have the advantage of: higher starting torque, quick starting and stopping, reversing, variable speeds with voltage input and they are easier and cheaper to control than AC. AC motor advantages include: lower power demand on start and minimal maintenance.
Which motor is used in tramways?
The DC motor was the mainstay of electric traction drives on electric and diesel-electric locomotives, street-cars/trams and diesel electric drilling rigs for many years. It consists of two parts, a rotating armature and fixed field windings surrounding the rotating armature mounted around a shaft.
Which induction motor is used in traction?
Several drives employing squirrel cage induction motors and synchronous motors are in use for traction. Variable frequency control is used both for induction motors and synchronous motors. Modes of operation of an induction motor traction drive are shown in figure 2.
Why 25kV is used in railway traction system?
The main reason for 25kV voltage used in railway is, that 25 kV AC more economical than 1.5kV DC voltage system. … Since 25kV voltage system has higher voltage, the higher voltage reduces the current flow through conductor; this reflects to reduce the conductor size.
How do traction motors work?
Traction motor refers to a type of electric motor. A traction motor is used to make rotation torque on a machine. It is usually changed into a straight line motion. Traction motors are used in electrically powered rail vehicles such as electric multiple units and electric locomotives.
Which traction system is best?
In case of heavy trains that require frequent and rapid accelerations, DC traction motors are better choice as compared AC motors. DC train consumes less energy compared to AC unit for operating same service conditions.
What is ideal traction system?
The requirements of an ideal traction system are. The locomotive should be self-contained and able to run on any route braking should be such that minimum wear is caused on the brake shoes if possible the braking energy should be regenerated and returned to the supply. Speed control should be easy.
What are the disadvantages of electric traction?
Disadvantages of Electric Traction (i) High initial expenditure (ii) Failure of supply is a problem (iii) Electrically operated vehicles have to move only on electrified track (iv) For braking & control, additional equipments required (v) Interference with telegraphs and telephone lines.