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Can you explain why there is an armature voltage even the field current is zero?
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What are the factors that influence the speed of the direct-current shunt motor with increasing load?
.The magnitude of the voltage and current of both the armature and shunt field coil. To decrease the speed when the load is increasing then increase the shunt field current while decreasing the armature voltage or current. To increase the speed while the load is increasing then increase the armature current while decreasing the shunt field current. The decreasing and increasing of these currents and voltages can be done by connecting a variable resistor in series or parallel with each of the armature and/or shunt field coil.
Why does voltage increase with current with separate excitation?
More current in the field coils means a stronger magnetic field for the armature to rotate in. This causes the output voltage for a generator to increase. For a motor, more magnetic field means that the supply voltage can be matched at a slower armature rotation speed, so the motor runs more slowly but can supply more torque.
What is the working principle of a DC shunt motor?
To ensure that the Lathe machine's motor working properly, DC motor starter is added in which it used to protect motor against damage from: • short-circuit, • long term overload, • excessive starting current, and yet to made the operating speed of motor easily to be control by operator. During starting, the motor is not turning, hence there is no internal voltage .The internal resistance is very low and thus the current flow through is very high. This condition may cause damage to the motor Hence, a staring resistor is added in which connect in series with the armature to limit the current flow until the internal voltage of motor is increasing to do the limiting. In order to prevent losses as the speed of the motor is build up; the starting resistor should be removed
What is Comparison of armature controlled and field controlled DC servo motor?
Difference between field controlled and armature controlled is that field control is open loop and armature current is closed loop.
How speed increases when flux decreases in dc shunt motor?
Increasing flux, torque of the dc motor will be increased and speed of the dc motor will be decreased as speed of the dc motor is inversely proportional to that of the flux and the torque of the dc motor is directly proportional to the flux.
What are the factors that influence the speed of the direct-current shunt motor with increasing load?
.The magnitude of the voltage and current of both the armature and shunt field coil. To decrease the speed when the load is increasing then increase the shunt field current while decreasing the armature voltage or current. To increase the speed while the load is increasing then increase the armature current while decreasing the shunt field current. The decreasing and increasing of these currents and voltages can be done by connecting a variable resistor in series or parallel with each of the armature and/or shunt field coil.
What is the function of field winding in DC generator?
The motor needs the current and magnetic flux to create motion The magnetic field is created by field winding where as armature carries the current resulting into the rotation of armature
How does a small generator produce current?
It doesn't! It produces voltage. It does this by the relative movement between an armature (winding into which a voltage is induced) and a magnetic field (set up by field windings). Either the armature rotates inside a fixed field (small generators) or the field rotates within a fixed armature (larger generators).Current is only supplied when a load is connected to the generator.
What is the difference between shunt generators and series generators?
1. In Shunt generators armature current is equal to sum of field current and load current whereas in series generators field current and load current is same. 2. Shunt generators field winding has high resistance and large no of turns as compared to series generators. 3. Shunt generator field winding has thin conductor and series generator has thick.
What is mean by armature reaction?
armature reaction means when load is added to the armature then current is passed through armature conductors then in armature creates flux. It is demagnetize and cross magnetize the main field flux. in other ward it is effect of armature field on main field.
Why does voltage increase with current with separate excitation?
More current in the field coils means a stronger magnetic field for the armature to rotate in. This causes the output voltage for a generator to increase. For a motor, more magnetic field means that the supply voltage can be matched at a slower armature rotation speed, so the motor runs more slowly but can supply more torque.
What is the excitation system in a generator used for?
The excitation system is used to control the excitation of the rotating field in the armature. By increasing the armature current, it in turn increases the magnetic flux in the armature coil. This has the effect of increasing the voltage output of the generator. By lowering the armature current this in turn lowers the generator output voltage. The generator's voltage regulator automatically adjusts the output voltage continuously as the applied load on the generator changes.
What is short circuit ratio of an alternator?
Short circuit ratio is the ratio of field current required for the rated voltage at open circuit to the field current required for the rated armature current at short circuit
What is the working principle of a DC shunt motor?
To ensure that the Lathe machine's motor working properly, DC motor starter is added in which it used to protect motor against damage from: • short-circuit, • long term overload, • excessive starting current, and yet to made the operating speed of motor easily to be control by operator. During starting, the motor is not turning, hence there is no internal voltage .The internal resistance is very low and thus the current flow through is very high. This condition may cause damage to the motor Hence, a staring resistor is added in which connect in series with the armature to limit the current flow until the internal voltage of motor is increasing to do the limiting. In order to prevent losses as the speed of the motor is build up; the starting resistor should be removed
Can you explain why there is an armature voltage even then the field current is zero in case of separately-excited dc generator?
if this happened it will be due to residual magentism and as soon as this magentism vanishes no voltage will be available , what iam saying can be interpreted mathematically first the generated emf across the armature is given by E= k* flux* speed it is clear due to this equation the emf is directly prportional to the flux which means if the flux is reduced so does the emf and the revers is true, the reduction may be lead to zero flux value and thus the emf (zero field current) secondly this emf covers the terminal voltage and the drop in armature winding if other possiple drops are ignored as E= terminal voltage + armature drop in this equation as E drops down as a result of reducing the flux and which in turn because of reduction in the field current , then right hand components will also drop down until both get zero values , so theoreyically no voltage will be exist at generator terminals when the field current comes to zero value, so the persistance of voltage is due to the residual field and will not last long
What is the use of magnetization curve of DC shunt generator?
The armature voltage is a critical parameter in the determination of performance characteristics for the DC machine. The armature voltage has been shown to be proportional to the magnetic flux density per pole and the armature speed. Thus, the armature voltage will also exhibit nonlinear behavior when saturation occurs. The analysis of DC machine performance typically requires that the characteristics of the armature voltage saturation be known. This information is typically provided in a plot of the armature voltage vs. field current (magnetization curve) for a given operating speed
Would a DC motor turn if only the armature were supplied DC voltage?
if there are magnets on the stator and the commutator is phased properly this is known as a permanent magnet dc motor the starting torque is dependent on armature current and the strength of the magnet the speed is directly proportional to the armature voltage a shunt motor needs the field energized for starting. more field more starting torque
