Series motors have poor speed regulation because a reduced load causes the speed to rise, which causes the current to drop, which causes the speed to rise more because there is less field.
Series motors are usually used to drive massive loads such as trams, where their high starting torque is a big advantage, and the speed cannot go out of control.
No load speed is the speed that the motor run when it has no load, i.e., the motor is separated from the engine, that speed is than greater than the rated speed, because the rated speed is the speed whwn the motor are linked to the load and it is the full load.
A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series DC motor
In series motor, At no Load Condition the flow of Armature Current is low, then the Flux is also low. Flux is inversely proportional to speed. If flux is decrease the speed is rapidly increase it spoil the rotor parts...... so SERIES MOTOR is start with LOAD.....
high torque
If a DC series motor is started without load, the armature winding (winding that doesn't spin) current will be at a minimum, resulting in the motor going to maximum speed / runaway, which can cause things to fly apart. As Armature current increases, the speed of the motor will decrease. The armature current will be forced to increase / speed of the motor will be forced to decrease as more and more load is applied.
Speed regulation in the series motor is quite poor.
A series motor can run away and reach a high speed on no-load, which happens because it accelerates until the back emf generated in the rotor is nearly equal to the supply voltage. On no-load the current and therefore the field are both small, so the motor speed has to rise to equalise the generated voltage.
The speed of a dc motor can be regulated by the following means:By varying the supply voltage and byUsing a variable rheostat.
you can control the speed of a motor by changing frequency, increase or decrease the field winding or by voltage regulation. in these method you can controle the speed of athree phese motor SANDEEP SARKAR
If they are connected in series the voltages will add and, theoretically, proportionally speed up the motor.
No load speed is the speed that the motor run when it has no load, i.e., the motor is separated from the engine, that speed is than greater than the rated speed, because the rated speed is the speed whwn the motor are linked to the load and it is the full load.
In any DC motor the speed depends inversely on the flux. Consider when starting a series motor the current flowing will be high, but the flux that the motor produces will be moderate since the series winding has less number of turns. If u start the motor without load the speed will increase. as speed increases the back emf increases. this decreases the current through the series winding and hence flux decreases and the speed further increases. Theoretically speaking the speed becomes infinite. But practically the motor will accelerate to very high speed , which will damage the motor. But if you start the motor with the load, you are actually reducing the starting speed hence the motor runs safely. Since series motors has this property it is used in trains to pull high load.
A dc series motor with speed control can be connected on ac supply because dc machines are totally reversible.
A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series DC motor
A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series DC motor
The DC series motor is a high torque motor. so that it can pull heavy loads such as traction, lifts etc., the control of speed of a DC series motor is very smooth and easy.
In series motor, At no Load Condition the flow of Armature Current is low, then the Flux is also low. Flux is inversely proportional to speed. If flux is decrease the speed is rapidly increase it spoil the rotor parts...... so SERIES MOTOR is start with LOAD.....