Available online
Description
This programme expands the basic principles behind the induction motor and goes on to show how industry develops a simple concept to build a sophisticated machine. The programme is presented by Pro...fessor John Sparkes and Dr David Blackburn. First of all the basic motor and generator principles are demonstrated and a loud speaker is then used to show how the two principles can be demonstrated in the same piece of equipment. The concept of a rotating magnetic field is explained using oscilloscope traces and a demonstration induction motor described. Finally, an industrial induction motor is used and its similarities to and differences from the demonstration motor discussed.
This programme expands the basic principles behind the induction motor and goes on to show how industry develops a simple concept to build a sophisticated machine. The programme is presented by Pro...fessor John Sparkes and Dr David Blackburn. First of all the basic motor and generator principles are demonstrated and a loud speaker is then used to show how the two principles can be demonstrated in the same piece of equipment. The concept of a rotating magnetic field is explained using oscilloscope traces and a demonstration induction motor described. Finally, an industrial induction motor is used and its similarities to and differences from the demonstration motor discussed.
| Module code and title: | T100, The man-made world: a foundation course |
|---|---|
| Item code: | T100; 07 |
| First transmission date: | 27-02-1972 |
| Published: | 1972 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:17 |
| + Show more... | |
| Producer: | David Nelson |
| Contributors: | David Blackburn; John Sparkes |
| Publisher: | BBC Open University |
| Keyword(s): | Concept; Generator; Induction motor; Industrial induction motor; Loud speaker; Oscilloscope; Production; Rotating magnetic field |
| Footage description: | Shots of a simple electric induction motor in operation. John Sparkes discusses the two fundamental electromagnetic principles operating in an induction motor. 1. Motor principle. Sparkes demonstrates using a magnet and a piece of electrified aluminium foil. Foil moves according to Fleming's Left Hand Rule. 2. Generator principle. A magnet and a copper coil are used to demonstrate this principle. Movement of the coil in a magnetic field generates an electric current. Motor effect and generator effect demonstrated. A search coil is mounted on a set of horseshoe magnets. Current is passed through the coil. The coil moves. Current is switched off and coil is moved over the magnets. Current is generated and monitored. The two principles are shown in practical operation. Motor effect creates vibrations in a loudspeaker (i.e. sound). The speaker can also be used as a transmitter by allowing sound vibrations to create an electric current. Sparkes explains the principle of generating a current in a conductor by a magnetic field, where the conductor moves with respect to the field and can react again with the same field to produce a force. He uses a simple coil and a bar magnet to illustrate. D. Blackburn demonstrates a method by which a rotating magnetic field is produced without rotating the magnet. He uses a pair of electromagnets. Variations in the magnetic field are shown on an oscilloscope screen. Blackburn shows that a rotating magnetic field of constant magnitude is produced by timing an alternating current in such a way that maximum magnetic force in one magnet corresponds to zero force in the other (and vice-versa). A modern industrial induction motor is examined by D. Blackburn. He looks at its components (Rotor and Stator) in detail and explains their functions. Blackburn shows how the motor works by placing a small model rotor inside a large stator. |
| Master spool number: | 6LT/70478 |
| Production number: | 00521_2551 |
| Videofinder number: | 2151 |
| Available to public: | no |
