The Different Types of Transformers
Transformers either ‘step up’ or ‘step down’ AC voltage. They do do by magnetic induction.
Step Down types reduce the voltage coming out, compared to the voltage going in. These are the most common type.
Step Up types have a higher output voltage than an input voltage. These are used for example at power stations to boost up the voltage that is fed onto the pylons. Higher voltage reduces losses over distance. It is then reduced again as it approaches towns where the users are located.
There are both ‘Single Phase’ Transformers, and ‘Three phase’ Transformers.
Single Phase Transformers have one ‘Primary’ coil, and one ‘Secondary’ coil. The Alternating Current is fed into the Primary, and comes out of the Secondary.
Three Phase types have three Primary coil windings, and yes you guessed it correctly, three secondary (output) coil windings.
Transformers are available in a wide variety of voltage and current outputs, ranging from a few volts up to thousands of volts, for high voltage electricity distribution.
Are Transformers AC or DC?
Transformers work by electromagnetic induction.
To generate electricity you need to move a varying magnetic field within a coil of wire.
This can be done in two ways:-
Firstly you could get a coil of copper wire and move a magnet in and out of the coil, which would generate electricity.
As the magnetic would be moving in and out of the coil, the magnetic ‘field strength’ would be continually changing.
If a suitable meter was connected to each of the two ends of the coil wires, then it would be showing a variable voltage.
This variable voltage is AC.
The second way to generate Alternating Current is to substitute the moving magnet used in the first method, with an alternating voltage.
Transformers work by this method, and an Alternating Voltage is run through the first coil (known as the ‘Primary Winding’), which induces a (normally) different voltage in the second coil (known as the ‘Secondary Winding’).
By varying the ratio of coil windings between the Primary Winding and the Secondary Winding, you can alter the output voltage to the desired level.
The transformer output is usually fixed at the time of manufacture, though some transformers have ‘tapped windings’ which are physical connection at different points along the transformer winding, allowing different voltages to be selected.