Available online
Description
First part of the programme stresses the importance of knowing the exact form of an AC signal which is being measured. The second part deals with power factor correction.
First part of the programme stresses the importance of knowing the exact form of an AC signal which is being measured. The second part deals with power factor correction.
| Module code and title: | TS282, Electromagnetics and electronics |
|---|---|
| Item code: | TS282; 09 |
| First transmission date: | 20-05-1972 |
| Published: | 1972 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:22:41 |
| + Show more... | |
| Producer: | Tony Jolly |
| Contributors: | Gary Alexander; John Sparkes |
| Publisher: | BBC Open University |
| Keyword(s): | Average full wave rectifier meter; Capacitor; Fluorescent lamp; Peak reading meters; RMS voltage reading meters; True RMS |
| Footage description: | Professor Sparkes introduces the programme. He shows three different rms volt meters being fed with a pure sine wave signal. Readings are the same, but when fed with a square wave signal, all read differently. Sparkes explains that the meters respond to true rms, peak values, and the average of the full wave rectified signal, respectively. It is therefore essential to know the form of the AC signal being measured. He feeds the meters with another wave form and asks students to note down the readings in connection with the CMA for Unit 9. Gary Alexander uses an inductive load to demonstrate that average power is not always the product of rms voltage and current. He explains this with graphs. John Sparkes and Gary Alexander show the wave forms of the input voltage, power in the circuit and power being dissipated. By placing a ferrite rod in the coil used in the circuit, Sparkes explains power factor and shows how it can be reduced by placing a capacitor across the input. Gary Alexander shows the parts and circuit of a fluorescent tube utilising power factor correction. Finally Sparkes repeats the data for the CMA. |
| Master spool number: | 6LT/70496 |
| Production number: | 00521_2109 |
| Videofinder number: | 703 |
| Available to public: | no |
