40 lines
1.4 KiB
Markdown
Executable File
40 lines
1.4 KiB
Markdown
Executable File
---
|
|
author: Akbar Rahman
|
|
date: \today
|
|
title: MMME2051 // Transformers
|
|
tags: [ transformers, alternating_current, ac ]
|
|
uuid: 486f441f-14ec-41e5-94f9-06f25c534086
|
|
lecture_slides: [ ./lecture_slides/MMME2051EMD_Lecture8.pdf ]
|
|
exercise_sheets: [ ./exercise_sheets/Exercise Sheet 11 - Transformers.pdf ]
|
|
---
|
|
|
|
Transformers are used to convert between AC voltages.
|
|
|
|
Transmission is always done at very high voltage to reduce copper losses (heat loss, $E = i^2R$).
|
|
|
|
|
|
|
|
A current carrying coil induces a magnet inside the core.
|
|
Another coil is wrapped around the core.
|
|
This coil has a current induced in it by induced magnetic field.
|
|
|
|
|
|
|
|
$$\frac{i_s}{i_p} = \frac{v_p}{v_s} = \frac{n_p}{n_s} = \text{turns ratio}$$
|
|
|
|
**Note that the current fraction is s over p, not p over s like the others.**
|
|
Transformers have very high efficiency so will not be considered for this module and
|
|
has been left out of the equation above.
|
|
Derivation in lecture slides (pp. 12-15).
|
|
|
|
Transformers are usually described as having a ratio $p:s$, where $p$ is the number of primary coils
|
|
and $s$ the number of secondary coils.
|
|
|
|
|
|
|
|
## Referred Impedance
|
|
|
|
$$\frac{Z_P}{Z_S} = \left(\frac{n_p}{n_s}\right)^2$$
|
|
|
|
Derivation in in lecture slides (pp. 19-21).
|