1 / 16

Group 3

TYLEEN JOHNSON LUKE WILSON JOSE CHAVEZ

pdxgoofy
Download Presentation

Group 3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GT 107 WINTER 2012 Combined group 3 presentation

  2. MOTORS Shaded-pole Wound-rotor • Just a basic induction motor • Shaded-pole refers to the method of starting • Weak starting torque • Unique ability to gradually bring up to speed large loads easily and smoothly. • Can develop high starting torque at standstill

  3. MOTORS SHADED POLE

  4. Reliable and Cheap • There are probably more single-phase A/C induction motors in use today than the total of all the other types put together. • It is logical that the least expensive, lowest maintenance type of ac motor should be used most often. The single-phase A/C induction motor fits that description. • Shaded-pole AC drives are usually found in fans, whether in your computer, ceiling, window, or air-conditioning system

  5. Basic Induction Motor Voltage is induced in the rotor as a result of magnetic induction, and a magnetic field is produced around the rotor. This field will always be in opposition to the stator field (Lenz's law applies). The interaction between the rotor and stator fields will not produce rotation, JUST PUSH OR PULL (Along the center yellow arrows) Stator changes polarity with A/C polarity changes

  6. Because the two fields continuously alternate, they will never actually line up, and the rotor will continue to turn once started • Shaded pole motors are used where low torque is acceptable (such as fans) and are usually less than 1/4 HP. Due to their very low efficiency, shaded pole motors should only be used in applications where the motor is either very small or operates for very short periods of time (e.g. shower fan motor).

  7. Basic Induction Motor Add rotation by any outside force, the push-pull along the center line is disturbed. At this instant the south pole on the rotor is being attracted by the left-hand pole. The north rotor pole is being attracted to the right-hand pole. The pull that now exists between the 2 fields becomes rotary force TURNING THE MOTOR

  8. Shaded-pole version The shaded-pole motor's start winding consists of a copper band across one tip of each stator pole . This copper band delays the magnetic field through that portion of the pole. When ac power is applied, the main pole reaches its polarity before the shaded portion of the pole. This action causes the shaded poles to be out of phase with the main poles and a weak rotating magnetic field is produced. This is the “outside force” that starts the shaded-pole motor!

  9. (You might need to click the black box) (http://youtu.be/PmNcRsxSovs

  10. MOTORS Wound rotor

  11. Variable Resistance offers unique applications • You can control the speed, torque, and resulting heating • Incorporates brushes and slip rings • Typical applications include conveyer belts, hoists and elevators.

  12. A wound-rotor motor is a type of induction motor where the rotor windings are connected through slip rings to external resistances The wound-rotor induction motor is an A/C electrical motor that is powered by three-phase AC voltages.

  13. Instead of a series of rotor bars, a set of insulated rotor coils is used to accept external impedances. The rotor windings are similar to those found on a DC armature, with the coils connected together to a set of rings that make contact with brushes. The circuit is completed by connecting the brushes to a set of impedances such as a resistor bank or liquid rheostat.

  14. By modifying the resistance, the speed-torque characteristics can be altered. This allows for the torque to remain high, the inrush low, and the speed varied.

  15. Used with permission from www.wisc-online.com

  16. GROUP3 GT107 is TYLEEN JOHNSON LUKE WILSON JOSE CHAVEZ

More Related