Instrument Transformer

In this article we will discuss about the instrument transformer . we learn about type of instrument transformer

The transformer which is used with measuring instrument and used to measure the high voltage and high current is called instrument transformer.

There are mainly two types of instrument transformer

1. Current transformer

2. Potential transformer

The current transformer is used for measuring the current of high tension and extra high tension lines.it is a step-up transformer. It has a primary winding of few turns of even a single turn to carry the current to be measured and is connected in series with the main circuit. The secondary winding consists of more turns of thinner wire and connected across the ammeter terminals as shown in diagram.

Hence, the electric current of 100-200 A of primary circuit, is converted into the electric current of 1-2 A and this current is measured by the ammeter which is connected with the secondary as shown in figure below.

This type of transformer is used for measuring the voltage of high tension lines. It is a step-down transformer and is connected in parallel with the circuit. It has a primary winding of large number of turns of fine wire connected to the line whose voltage is to be measured. The secondary winding consists of few numbers of turns of thick wire and is connected across the low range voltmeter. For safety, secondary winding should be completely insulated from the high voltage primary and shoud be additionally grounded for providing protection to the worker.

When primary winding of transformer is connected with an AC supply, then due to the flow of alternating current, a magnetic flux or field of alternating nature is developed which completes its path through the common magnetic core. Hence these principle working on instrument transformer.

The conductors of secondary windings cross the magnetic field lines which were set up by magnetic field of primary windings, these results in producing field of primary windings, these results in producing the magnetic flux of alternating nature in secondary windings.

This flux induces and electromagnetic force according to the faraday’s law of electromagnetic induction.

In this way, without any connection or touch, an electrical energy is transferred between the primary and secondary winding, this action is called the transformer action. If now load is connected to the secondary winding, the induced EMF drives a current though it.

1. it is a static device and there is no movable parts in it and hence, no tear and wear of it.

2. it requires very little care and maintenance.

3. No attention or little attention is required for its operation so its maintenance cost is low.

4. its life is more.

5. the Voltage can be easily stepped up and stepped down according to the requirement.

6. it has a high efficiency.

7. transmission and distributing become cheaper, as a result aluminum or copper is saved.

Hence it is the instrument transformer if you will find any incorrect above please comment below.

For knowing more about instrument transformer you must watch this video.