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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.
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What is the main disadvantage of series generator?
Speed regulation in the series motor is quite poor.
Why induction motor speed is always less then synchronous speed?
induction motor never runs at synchronous speed, if it does so there would not be any relative speed between stator flux and rotor and no emf will induce in rotor and we can not apply motor principle as we need current carrying conductor in magnetic field.
Why does the speed of the DC series motor rise to a run away condition if full voltage is applied while there is no load?
At no load, the speed of a series motor rises to a run-away condition if the full voltage is applied because the applied voltage appears directly at the terminals of the motor and drives it to a run-away condition since speed is proportional to the voltage.
Why the series motor is started with some initial load?
In dc motors Speed is directly proportional to back emf and inversely proportional to flux i.e N∝(Eb/φ) In series motor back emf is practically constant. So if we start motor without any load Flux will be small and so speed will be very high. if we start motor without any load it will gain very high speed and may get damaged due to centrifugal forces. Series motor have very high starting torque and used where high starting torque is required.
The device which disconnects the start winding in some split-phase motor circuits after a preset speed is obtained is the?
It is called a centrifugal switch. The switch is in series with the start winding. When the RPM of the motor reaches a certain speed the switch drops the start winding of the motor out of the circuit.
What is the main disadvantage of series generator?
Speed regulation in the series motor is quite poor.
Why the speed regulation does not apply to series motor?
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.
What are 2 mathod of speed regulation in DC motor?
The speed of a dc motor can be regulated by the following means:By varying the supply voltage and byUsing a variable rheostat.
What are the various method of speed control of 3 phase induction motor?
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
Does the number of batteries affect the speed of a motor?
If they are connected in series the voltages will add and, theoretically, proportionally speed up the motor.
What is the speed of DC series motor at no load?
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.
Why should a series motor always start with a 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.
Can a DC series motor with speed control be connected on AC supply?
A dc series motor with speed control can be connected on ac supply because dc machines are totally reversible.
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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
What is DC shunt 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
What is Advantages of using 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.
Why the series motor is started with some minimum load?
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.....
