I had once stayed six months in a blackout because the transformer supplying our region got bad. If you are in Nigeria, it is common talk to hear about transformers (especially when it's faulty), you may likely see it along the road as you walk or drive by. What is a transformer? Why is that piece of electric equipment important?
Let us start with the former question.
Source: A Power Transformer in an Electric Power Station
An electric transformer is a static (no moving parts) electrical device that transfers electrical energy between two or more circuits through the process of electromagnetic induction.
Electromagnetic induction is simply the production of electromotive force (emf) or voltage due to a change in the magnetic field.
The transformer basically works through the principle of electromagnetic induction.
There are three basic components of a transformer:
The Primary Winding: This receives energy from the power source.
Secondary Winding: This delivers energy received from primary windings to the output (load).
The Core: That is the magnetic circuit which provides a path for the flow of magnetic field (magnetic lines of flux) around it.
The Enclosure: This is the protective part of the transformer that shields the above-listed components from mechanical damage, moisture, and dirt.
An alternating current applied to the primary coil, a magnetic field (an invisible magnetism pattern) is generated. This magnetic field is sometimes referred to as magnetic flux. The strength of this generated magnetic flux is dependent on the size of current applied to the primary coil. Through the principle of electromagnetic induction, a fluctuating, magnetic field around a piece of wire induces current on the wire. This current is referred to as primary current, denoted by Ip. If a second coil (secondary winding) is placed next to the primary coil, an electric current is induced in the secondary coil. This current is known as the secondary current and is denoted by Is.
It is important to note that the primary and secondary coils of a transformer are not physically connected, current only moves from one winding to the other via electromagnetic induction.
There is another important aspect of a transformer that determines the type and/or function of the transformer. It is dependent on the transformer turns ratio (TTR).
This is the ratio of the number of turns of wire in the primary winding denoted by Np, to the ratio of the number of turns of wire in the secondary winding denoted by Ns.
To calculate the TTR, you would use the following equation:
Vp/Vs = Np/Ns= Is/Ip
Vp = Voltage on the primary winding
Vs = Voltage on the secondary winding
Np = Number of turns of wire in the primary winding
Ns = Number of turns of wire in the secondary winding
Is = Current on the secondary winding
Ip = Current on the primary winding
Ns < Np
In step down transformer, the secondary voltage is always smaller than the primary voltage.
But as you could see the power in this example (2000w) never changes. Transformer only changes current and voltage but never frequency and power (though there may be some power loss due to eddy current or I2R losses).
In step up the primary winding is smaller than the secondary winding.
Np < Ns
The input primary voltage Vp is always smaller than the secondary voltage Vs
It is important to mention another type of transformer known as isolation transformer. The ratio of the primary to secondary windings respectively is 1:1. Theis means that both the number of turns in the primary winding Np is same as the number of turns of the secondary windings Ns.
Vp = Vs
The transformer has got a very wide application in both electrical and electronics systems. The functions of a transformer include:
2. Electric Distribution: A step down transformer is needed for distribution of the high voltage coming in from the transmission station.
These are the types you commonly see hanging from electric utility poles and besides street corners.
3. Protection: Isolation transformers protects us from dangerous voltages and isolates circuits from damage.
4. Measurements: We have different types of electrical measures. Examples include current, voltage, power, etc. So there are special transformers such as current transformers, potential transformers, etc.
5 Filter: A transformer could serve as a block or filter that prevents the direct current (DC) from passing a particular point since only alternating current (AC) could pass through the transformers.
These are some of the uses as this is not an exhaustive list just something for us to use to gain some insights on the transformer. Thank you for reading.
