The performance and design of direct current machines pdf
The performance and design of direct current machines ( edition) | Open LibraryWhile some may claim that direct-current DC motors are no longer relevant, that is definitely not the case. Alternating-current AC motors have certainly decreased DC motor sales, and they do confer advantages in some applications. Understanding the differences between AC and DC motors reveals where each works best and helps guide selection and specification. The basic operation of all these designs is similar. A current-carrying conductor is placed in a magnetic field, and applying power through these conductors causes motor rotation. The difference among the designs is how the electromagnetic fields are generated and where — in either the rotor or stator.
DC Motor, How it works?
Performance and design of direct current machines by clayton pdf
To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. Desibn this reason, lamination thickness should be kept as small as possible. Click here to sign up. The other terminals of the armature and shunt field windings are connected to the negative terminal of the supply.
The motor with presence of 7th harmonics is to have a tendency to run the motor at one seventh of its normal speed! Permissible losses and range of efficiency 8. Single phase Induction Motor: Design of running and dirdct windings for capacitor start induction motor. The length of the rotor can be kept small and diameter can be made higher 2.
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Define stacking factor. Therefore, the average value of current through any particular coil is the same. Forming the constraint functions for the pedformance 4! It is because a voltmeter cannot read the e?
Induction eliminates the need for brushes which is usually a weak part in an electric machine. If the temperature of a material is raised above its critical temperature its superconductivity disappears. Space factor: Window space factor Kw Window space factor is defined as the ratio of copper area in the window to the area of the window. Other electromagnetic machines include the AmplidyneHysteresis!
This book deals with principles and with the practice of electrical design. In the actual design of any apparatus the designer will naturally work in terms of units which in his view are best suited from all considerations. Thus some leading designers of electrical machinery have used the inch; others including the author have used metric units expressing dimensions chiefly in centimeters but using the larger and smaller units-the metre kilometer and millimeter-freely where circumstances warranted their use. It is simplicity itself to modify fundamental formulae and data developed either with m. Certified Buyer , Jodhpur. Explore Plus.
In this case curtent finished designs of machines must be produced in groups ,where all designs with in a group are independent. Current density: Higher current density reduces the volume of copper but increases the losses and temperature. Note that full lines represent the top machnes sides or conductors and dotted lines represent the bottom coil sides or conductors. They are electromechanical energy converters: an electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. Its shape is practically the same for all generators whether separately or self-excited.
What is askarel. Therefore, this method of speed control is employed for large size motors where efficiency is of great importance. These are having the advantage of rugged and simple in construction and comparatively cheaper. Iron losses occurring in desigb stator can be computed as given below.
We can examine this here. Electromagnetic fields Both the fields stores some energy. However in induction motors the flux density in the airgap should be such that there is no saturation in any part of the magnetic circuit. For choice of no.Maximum value of flux density that can be used is about 1. The results of analysis method are highly acceptable by designers. This necessitates frequent shifting of brushes. There are now two parallel paths into the brush as long as the short-circuit of coil A exists.
The armature control method is a very common method for the speed control of d. Give an expression for the heating time constant of transformer. The armature flux distorts o weakens the main flux posing problems for the proper operation of the d? Generators with fairly higher speeds are built with horizontal shaft and the generators with higher power ratings and low speeds are built with vertical shaft design.