What does a transformer actually do?

The transformer is not a car that turns into a robot. You should still respect him when you meet him. About its key role in our everyday life


  • definition
  • species
  • Functions
  • Turns ratio
  • Today’s use
  • Galvanic separation

The transformer: definition and origin

This word is derived from the Latin “transform” and means to transform or transform. It is also affectionately referred to as a “transformer” by fans and users. Synonymous is a transformer. Since its invention by Lucien Gaulard and John Dixon Gibbs (London) in 1881, the transformer has spread and can now be found all over the world.

What is a transformer?

The transformer is a technical system of energy technology. The component consists of coils, copper wire and core: the multi-wound wires are immediately noticeable; they are a bit reminiscent of coiled sewing thread. In most use cases, the transformer’s job is to increase or decrease electrical voltages. Transformers convert an incoming alternating voltage in a certain ratio (e.g. 20 to 1, that depends on the coil windings) into an outgoing alternating voltage b. So that’s what a transformer does: it transforms AC voltages (not DC voltages). Transformers are hidden in small, free-standing buildings or in the small rooms of large buildings: It is relatively shy and not entirely harmless when it is life. A transformer can give you a huge electric shock if you get too close without warning or precautions. That’s why he wants to keep most people away with the following label:

The transformer only allows selected people to visit. Then it can also be that he can switch off properly and all the tension of everyday life falls away from him.
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Different transformers.

The transformer is available in a wide variety of sizes, designs and colours. Many electrical devices or electricity consumers in our household have a small transformer, as the required operating voltage often differs from the mains voltage. There are chargers for cameras, smartphones, tablets and laptops in every household – there are transformers in every single one.
The big brother of the device transformer, on the other hand, is used for power distribution in industry and by the Electricity network operators used. It is called a distribution. In its largest form, the transformer lives in the substation. There he is the link between the tension levels of Power grids. It is also called a network transformer.

The capabilities and inner values ​​of the transformer

The main area of ​​application for transformers is to increase or decrease alternating voltages. What enables the transformer to convert voltages? In order to be able to answer this question, we have to dive deeply into the field of electrical engineering. If this is too technical for you, you can skip the following paragraph. 
The principle of operation of the transformer is based on the law of induction. In terms of construction, the transformer usually consists of a ferrite or iron core and electrical conductors that are wrapped around this core several times. It basically has an input side or primary side and an output side or secondary side. The windings are called the primary and secondary coils. There is also a sketch of the transformer for illustrated reflection:

The iron core of the transformer is wrapped in two coils in which current flows (electrical energy source on the primary side: I1). The windings are isolated from each other. The functioning of it is based on the induction law and Ampère’s law.

An alternating voltage applied to the primary side causes an alternating magnetic flux in the iron core of the transformer in accordance with the law of induction. This means that a magnetic field is created that changes its polarity cyclically due to the applied alternating voltage. The changing magnetic flux in turn induces a voltage on the secondary side of it.

What is a turns ratio?

If the number of copper windings on the primary and secondary sides is the same, the voltage on both sides of the capacitors is the same (in the no-load case, ie without load). In this case, the so-called “winding ratio” is equal to one. If the winding ratio is different, the voltage on the secondary side of the transformer changes. It, therefore, transforms the voltage on the input side to a defined voltage level on its output side. This is called stress transformation

Alternating Current and Ampere’s Law.

If an electrical consumer is now connected to the secondary side of the transformer, an alternating current flows in the secondary winding. So electricity is drawn. According to Ampère’s law, this current also causes an alternating current in the primary winding. The amperage, in turn, depends on the turns ratio. One speaks here of a current transformation.

The transformer in today’s energy technology

Transformers are indispensable for the power supply since electrical energy can only be transported economically over long distances using high-voltage lines. As you already know, the public power grid has different voltage levels. Size Power plants work with high voltages, but at home, we work with relatively low voltages. The link between these voltage levels.

The transformer converts the high voltage into low voltage – or vice versa.

A transformer is used to feed electrical energy from a higher voltage power grid into a lower voltage power grid. Since the transformer is a tolerant guy, it also works in the opposite direction. You can also feed generated electricity back into a higher voltage level.
Physically or mathematically, voltages and windings are calculated using the formula: U1: U2 = N1: N2 (voltage ratio for an ideal transformer). U1: voltage in volts at the first coil; U2: voltage in volts at the second coil; N1: number of turns of the first coil; N2: number of turns of the second coil.

Galvanic isolation.

The transformer gets a big plus point for its technical possibility for “galvanic separation” from Circuits. That sounds rather sad, but it isn’t.
Galvanic isolation rather means that two circuits are not connected to one another via an electrical conductor. The energy transfer takes place exclusively by induction in the magnetic field of the transformer core.
This offers every user increased safety, even if they are freed from any knowledge of the dangers of electrical current. If there is a short circuit in the device, the resulting fault current can flow through the human body upon contact with the device. That can be life-threatening. When using a transformer with galvanic isolation, this fault current remains very low and relatively harmless. 

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