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Difficulty Beginner Intermediate Advanced. Explore Documents. Uploaded by Nikhil Dixit. Document Information click to expand document information Description: abstract. Original Title Did you find this document useful? Is this content inappropriate? Report this Document. Description: abstract. Flag for inappropriate content. Download now. Save Save Original Title: Related titles. Carousel Previous Carousel Next. Sizing and Costing of Electrostatic Precipitators.
Jump to Page. Search inside document. AIM: The main aim of the project is to design a system which controls the speed of the uni ersal motor! Documents Similar To Nikhil Dixit. Sushil Kumar. Prashant Upadhyay. Anitha Prabakar.
In other words, separate closed loops encircle the stator yoke between the field poles. Both these arrangements of FIGS. The theory of operation is thought to be equivalent to the conductor loops or coils 26 and 28 in dampening or "soaking up" some of the generated energy. The closed conductor coils 26 and 28, located as shown in FIGS. The voltage across the coils and current through them causes the coils to impose a light electromagnetic load on the armature.
As the armature turns it creates its magnetic field even during a half cycle when the voltage is off because of the residual magnetism in the iron. That magnetic field sweeps past the closed conductor coils 26 and 28 inducing current flow in the closed coils and the combination results in an energy loss in the damper coils 26 and It appears that the coils simply act as a drain for the armature energy or in other words, the coils are soaking up some energy under the half sine wave. Thus, the energy which is not being used in the load is being consumed in the damper windings so that the closed conductors provide a means of getting rid of some of the energy without the speed of the motor rising perceptibly.
In effect, the energy is abstracted as heat in the damper windings so that as the current goes through another cycle, the SCR fires properly. While both arrangements of FIGS. The above is an attempt to explain the operation of the invention although there may be further and additional explanations.
It is necessary that the conductors 26, 28 be secured closed, preferably copper loops simply twisted together at 32 and 30 respectively and while no given size is necessary to improve operation, it has been found that copper wire smaller than No.
Obviously, any suitable means to secure the wire ends together may be used such as soldering, welding, staking, conventional connectors, or simply plain twisting as shown. As shown in FIGS. It should be apparent that the invention resides in both the specific apparatus by modifying a universal motor as described and in the method of providing smooth speed control at all settings of an SCR circuit controlled universal motor wherein the method comprises winding at least one metallic conductor loop wire around the stator magnetic flux path as shown in FIGS.
In both cases of winding the stator, the wire thus forms a closed loop generally parallel to the axis of rotation of the motor armature. While we have attempted to explain the operation of this successful means and method of controlling speed in an SCR controlled universal motor at all speeds and especially at low speed, low load settings, it may be that there are other explanations as to the theory of operation.
The method of control and the modification to a universal motor for this control has proved effective by the use of the closed loops as described. While there have been described preferred forms of the invention, equivalent variations may be possible in light of the above teachings.
It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described, and the claims are intended to cover such equivalent variations.
I claim: 1. In an SCR circuit controlled universal motor, means for providing smooth speed control at all speed settings comprising, a series wound stator field in said motor, and.
Apparatus as described in claim 1 wherein said conductor is a closed copper loop. Apparatus as described in claim 2 wherein said copper loop is 10 gauge or greater. Apparatus as described in claim 1 wherein the conductor loop encircles the poles of the motor at each end thereof. Apparatus as described in claim 1 wherein separate closed conductor loops encircle the stator yoke between the poles.
Apparatus as described in claim 1 wherein the conductor loop is generally parallel to the axis of rotation of the motor armature. The method of providing smooth speed control at all speed settings of an SCR circuit controlled universal motor comprising, winding at least one metallic conductor wire around the stator magnetic flux path, and. The method of providing smooth speed control at all speed settings of an SCR circuit controlled universal motor comprising, winding at least one copper wire conductor of 10 gauge or greater around the stator magnetic flux path, and.
The method described in claim 8 wherein the winding is done around first one portion of the stator yoke between the field coils and then a separate second wire is wound around the opposing portion of the stator yoke between the field coils, and securing each wire separately at its respective ends forming separate closed coils.
The method of claim 8 wherein the winding is done in a direction generally parallel to the axis of rotation of the motor armature. DE DEA1 en USA en. JPSA en. DEA1 en.
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