A V, 4-pole wave wound DC series motor has conductors on its armature; it has armature and series field resistance of 0. The motor takes a current of 30 A.
Estimate its gross torque developed if it has a flux per pole of 25 mWb. A 4-pole, long shunt lap wound generator supplies 20 kW at a terminal voltage of V. The armature resistance is 0. The brush drop may be taken as 1. Determine the induced EMF. The yoke for large D. Three point starter is used to start. The speed of a D. Motor is directly proportional to. Which feature of D.
The motor used for loads with high starting torque requirement is Overall commercial efficiency of DC motor is If load torque varies with the square of speed and terminal voltage of DC shunt motor is halved, then the speed:. Suggested Test Series. Suggested Exams. More Electrical Machines Questions Q1. An 8-pole, 3-phase induction motor operates from a supply whose frequency is 50 Hz.
Calculate the speed at which the magnetic field of the stator is rotating. In a synchronous motor, the value of coupling angle depends on:.
In which of the following tests, which may be used to measure the synchronous impedance, should the reading be taken in a short time to avoid armature overheating? A 3-phase induction motor has a slot, 9-coil, 4-pole stator. Calculate the number of coils per phase. In a DC motor, the stator provides a rotating magnetic field that drives the armature to rotate. DC controls adjust speed by varying the voltage sent to the motor this differs from AC motor controls which adjust the line frequency to the motor.
Typical no load or synchronous speeds for an AC fractional horsepower motor are or rpm, and rpm for DC fractional hp motors. Begin typing your search term above and press enter to search. Press ESC to cancel. Skip to content Home Research Paper What makes the electrical connection between the power source and the commutator in a dc motor?
Research Paper. Ben Davis April 28, What makes the electrical connection between the power source and the commutator in a dc motor? What is the purpose of commutator?
What are the causes of sparking on the commutator? Which terminal of the commutator is connected to the positive terminal of the current supply? Which applications require high starting torque? Which type of following motors are most efficient?
Which type of load requires large torque at starting? Which DC motor is used for conveyor? What controls the speed of a DC motor? For an excellent visual showing how the current is switched due to the position of the coils and brushes, see this article from the University of Utah. The commutator itself is a split ring, typically made of copper, with each segment of the ring attached to each end of the armature coil. If the armature has multiple coils, the commutator will similarly have multiple segments—one for each end of each coil.
Spring-loaded brushes sit on each side of the commutator and make contact with the commutator as it turns, supplying the commutator segments and the corresponding armature coils with voltage. As the brushes pass over the gaps in the commutator, the supplied electrical charge switches commutator segments, which switches the electrical polarity of the armature coils.
The voltage between brushes fluctuates in amplitude between zero and a maximum value, but always maintains the same polarity.
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