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In D.C Shunt motor, the field winding is connected parallel with the armature winding.. If you remove the supply to armature winding, the motor will stop after some time.
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What motor must be never run without a load connected to them?
DC Series motor should never run without load connected to it because starting torque for DC series motor is infinite and running it on no load will damage the motor due to overspeeding.
What happens when a curcuit is closed?
To close a circuit in electrical terminology is to close any open devices that are in series with a connected load. Once this happens the current will flow through the load and the load is then termed as energised. In the case of a motor circuit the motor will operate. In the case of a lighting circuit the lamps in the circuit will energise and light the area in which they are installed.
Why speed regulation does not apply in dc series motor?
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.
Why can we start a shunt motor under no load but why can't a series motor?
The torque on a series motor is determined by the square of the armature current and, so, is very large -much larger than that of a shunt motor. Consequently, on starting, with no back-emf being generated, the torque on a series motor can be dangerously high if the machine has no mechanical load.
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.
What is the kind of circuit in which an electrical load may be disconnected without affecting other loads?
In a parallel circuit an electrical load may be disconnected without affecting other loads.
What motor must be never run without a load connected to them?
DC Series motor should never run without load connected to it because starting torque for DC series motor is infinite and running it on no load will damage the motor due to overspeeding.
What happens when load is removed from an operating series DC motor?
The speed will increase possibly to the point that it throws out the coils from the armature & self destructs.
What happens when a curcuit is closed?
To close a circuit in electrical terminology is to close any open devices that are in series with a connected load. Once this happens the current will flow through the load and the load is then termed as energised. In the case of a motor circuit the motor will operate. In the case of a lighting circuit the lamps in the circuit will energise and light the area in which they are installed.
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.....
Why speed regulation does not apply in dc series motor?
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.
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 dc series motor is always runs at loads?
At no load, the flux is only due to the residual flux, which is very small. the no load speed of dc series motor is very high. so the rotating part of the motor are damaged. hince dc series motor should never be run without motor.
Why can we start a shunt motor under no load but why can't a series motor?
The torque on a series motor is determined by the square of the armature current and, so, is very large -much larger than that of a shunt motor. Consequently, on starting, with no back-emf being generated, the torque on a series motor can be dangerously high if the machine has no mechanical load.
What would the power loss be if the series field winding of dc motor connected directly across the 240 V dc supply?
Detailed Solution. For a constant back emf, flux is inversely proportional to the speed of the motor. If field winding is disconnected accidentally, the speed would dangerously increase in order to maintain the back emf of the motor
Why no load-speed of a dc series motor is very high?
high torque
Why dc series motor cannot be start without any load?
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.
