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A 220volts series motor takes 15amperes and runs at 700rpm the armature resistance of the series winding is 0.8 ohms at what speed will it run if resistance is connected in series with supply voltage?
It will run slower because the resistance in series with the motor will take some of the voltage and thereby reduce the current to the armature windings (less magnetic field).
What unit contains a hold-in winding and a pull-in winding?
A relay unit typically contains both a hold-in winding and a pull-in winding. The pull-in winding is energized to initially attract the relay armature and close the contacts, while the hold-in winding is activated once the armature is in place to maintain contact. This design allows for energy efficiency, as the hold-in winding usually requires less power to keep the relay engaged.
Why dc series motor should start with load?
In DC Series Motors the field is in series with Armature. When the motor starts at no load, the armature current is very low and so is the field current. As the speed of DC Motor is inversely proportional to field current, the motor will try to shoot up to very high speed at no load and it can be dangerous for the motor itself and for this reason, any DC Motor should always be started on load.
Does a starting winding has more or less turns than a running winding?
Starting winding has more resistance and less induction than main winding, this means has smaller diameter and less turns.
Why shunt field resistance is high incase of dc shunt motor?
Back emf is proportional to the flux in the field winding.Flux in the field winding is proportional to the mmf in the winding.mmf = current passing through the winding * no of turns in the windingTo attain the required mmf we can use more current and less turns ( or ) less current and more turns .As the power loss in the field winding is considered it isPower loss = Square of voltage / resistanceAs the voltage is constant for a high resistance it is possible to have less losses. So we prefer for high shunt field resistance.As the field resistance is high current is less , so no of turns in the shunt field will be more to attain the required mmf.Answer'Shunt' is an archaic term for 'parallel', so the shunt winding is in parallel with the supply voltage which means its resistance must be relatively high to limit the current passing through it.Incidentally, the back-emf. is not proportional to the flux, but to the rate of change of flux.
Why armature resistance is less than 1 Ohm?
why armature resistance is very low as compare to field resistance in dc motor
A 220volts series motor takes 15amperes and runs at 700rpm the armature resistance of the series winding is 0.8 ohms at what speed will it run if resistance is connected in series with supply voltage?
It will run slower because the resistance in series with the motor will take some of the voltage and thereby reduce the current to the armature windings (less magnetic field).
What unit contains a hold-in winding and a pull-in winding?
A relay unit typically contains both a hold-in winding and a pull-in winding. The pull-in winding is energized to initially attract the relay armature and close the contacts, while the hold-in winding is activated once the armature is in place to maintain contact. This design allows for energy efficiency, as the hold-in winding usually requires less power to keep the relay engaged.
Why dc series motor should start with load?
In DC Series Motors the field is in series with Armature. When the motor starts at no load, the armature current is very low and so is the field current. As the speed of DC Motor is inversely proportional to field current, the motor will try to shoot up to very high speed at no load and it can be dangerous for the motor itself and for this reason, any DC Motor should always be started on load.
Does a starting winding has more or less turns than a running winding?
Starting winding has more resistance and less induction than main winding, this means has smaller diameter and less turns.
Why shunt field resistance is high incase of dc shunt motor?
Back emf is proportional to the flux in the field winding.Flux in the field winding is proportional to the mmf in the winding.mmf = current passing through the winding * no of turns in the windingTo attain the required mmf we can use more current and less turns ( or ) less current and more turns .As the power loss in the field winding is considered it isPower loss = Square of voltage / resistanceAs the voltage is constant for a high resistance it is possible to have less losses. So we prefer for high shunt field resistance.As the field resistance is high current is less , so no of turns in the shunt field will be more to attain the required mmf.Answer'Shunt' is an archaic term for 'parallel', so the shunt winding is in parallel with the supply voltage which means its resistance must be relatively high to limit the current passing through it.Incidentally, the back-emf. is not proportional to the flux, but to the rate of change of flux.
Is the resistance in the start winding greater or less than the resistance in the run winding?
The resistance in the start winding is greater because it is longer and thinner and has the greatest resistance to current flow
Why does the field winding of a series dc machine has less number of turns than that of a dc shunt machine?
The series winding takes the full load current of the generator. So it require only a few turns to produce the required magnetic field and so the resistance is lower.
Which winding has the higher resistance start or run in single phase motors?
start winding is thicker with less number of winding whereas run winding is less thicker than start winding but with more number of winding. As we know inductance depends upon numbers of turns of winding so run winding will have more inductance.
How you determine the starting and running winding of a capacitor start single phase motor?
I think the resistance value of starting winding is less than the running winding of the single phase motor
Why does motor speed increase with the increase of field resistance?
Motor speed increases with an increase in field resistance because higher field resistance reduces the current flowing through the field windings, which in turn decreases the magnetic field strength. A weaker magnetic field results in less counter-electromotive force (back EMF), allowing the motor to draw more armature current and thus operate at a higher speed. This behavior is particularly evident in shunt and compound motors where field resistance plays a significant role in speed regulation.
What are probable causes for not have build up voltage in a shunt generator?
1. Field Flashing. 2. Resistance of the filed winding should be less than critical field resistance. 3. Speed of the motor should be greater than critical speed. 4. Interchange the field connections. 5. Check the commutator surface and brush.
