DC shunt motors are not suitable for traction purpose, the reasons are given below: 1. The dc shunt motor is a constant speed motor and its speed-torque characteristic does not meet with the requirements of traction. i.e., the power drawn from supply mains varies directly as the load torque.
Which motor is used in traction?
AC traction motors have replaced DC motors in many traction applications. 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.
Which of the following motors is used for traction purpose?
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 type of DC motor is used for 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 motor is more suitable for traction service *?
For electric traction, DC series motors are best suited. DC series motors and AC series motors are very much recommended, as they provide a high starting torque Nowadays three-phase induction motors are also being used.
Are locomotives AC or DC?
All in all, the AC traction locomotive offers about twice the amount of adhesion as a DC unit. Therefore, a modern lightweight AC locomotive such as the RX500 can provide as much or more tractive effort than an old style DC unit like the SW1200 which weighs 60% more.
Why regenerative braking is not possible in DC motor?
In case of DC Series motor, as the speed of Motor increases, the armature current and hence the field flux will decrease and therefore Back emf E can never be greater than the supply voltage V. Therefore, Regenerative Braking is not possible in DC Series Motor.
What are the general features of traction motor?
Salient Features of Traction Motors
- Designs equipped with brush-rocker assembly, terminal box and axle roller suspension bearings.
- Polyimide film covered conductors for armature coils.
- Armatures built with high permeability electrical sheet steel.
- Potted field coils for better heat dissipation.
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.
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 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.
Which motor is not suitable for regenerative braking?
Regenerative braking is not possible in a series motor. Explanation: In regenerative braking, the motor acts as a generator. The back emf is more than the terminal voltage in case of regenerative braking. 2.
What does Traction mean?
1 : the pulling of or tension established in one body part by another. 2 : a pulling force exerted on a skeletal structure (as in a fracture) by means of a special device or apparatus a traction splint also : a state of tension created by such a pulling force a leg in traction.
Which braking method is the best method for obtaining high braking torque?
Which braking method is the best method for obtaining high braking torque? Explanation: Plugging is the best braking method among all braking techniques. In plugging the value of the armature current reverses and the mechanical energy is extracted. A very high braking torque is produced in case of plugging.