due to high starting torque and droping charactristics
DC Voltage
if you power an ac motor with dc or a dc motor with ac you will likely start smelling smoke and the motor will be damaged. If the motor is marked "3-phase", "shaded pole", or "induction" it is an ac motor! BTW, there are ac/dc motors that will run on both, they are wound very much like dc motors but a bit differently.
it maintains a constant speed under varing load
The easiest way would be to convert the AC power to DC by using a rectifier diode and a filter capacitor. In that way you can now run your DC motor on DC.
In its simplest form, the starter of a dc motor is a variable resistance in series with the armature circuit of dc motor to reduce the high starting current so that the armature winding does not get overheated and burnt while the motor isgetting started. As the rotating armature of dc motor picks up speed, the starter resistance is gradually reduced so that the motor is able to attain its full speed when the starter is not expected to offer any additional resistance in series with the armature winding of the dc motor. At full speed the motor starts running normally, of course, without the help of starter. In other words, the starter offers resistance to armature current during starting of dc motor only. Under normal working condition of dc motor , the starter is electrically out of armature circuit of the motor. The starter protects the armature of dc motor from getting damaged. The electromotive force (emf) induced in the armature winding during starting builds up from zero value to max value to restrict the armature current within the permissible value at full speed. As the speed of armature/motor build up, armature induced emf also starts building thus reducing the role resistance offered by the starter, hence requiring it to gradually reduce as the motor picks up full speed.
dc series motors
shunt type dc motor use in train fans
dc series motor used in metro train.
fast start low speed
An electric train uses electric motors. Modern trains have many motors, they are mounted on the axles, one motor per axle. Some axles will be powered and have motors on them, some will not.
dc series motor
what are the advanced applications of dc series motor
we can either use dc series motor or induction machine ,but dc supply is not easily available so we use induction motor ,
electric motors
A dc series motor can work on dc and ac because dc motors are totally reversible.
becoz of high starting torqe to move train
dc series motors are used because of torque vs speed characteristics.