Everything You Need To Know About Current Transformer

Transformers are appliances that change the voltage and current of electricity. They have two terminals which are either connected to an alternating current supply or a direct current supply, depending on the type of transformer being used.

The idea of transforming electrical current from one voltage to another is not new. It was first implemented long ago in power stations and electric power distribution systems, but it has taken some time for this technology to trickle down to the consumer level.

Here are some things you should know about current transformers so you can be more informed when shopping around for one.

What is a current transformer?

A current transformer (CT) is an electrical device that measures the flow of electric current and then converts it to a lower value to be used in the home or office.

A CT is used in conjunction with a voltage transformer that steps down the voltage of electricity coming into the home or office. A voltage transformer will reduce the voltage to a level suitable for use in lighting, computers, and other appliances.

The reduced voltage supply can then be fed into the building’s wiring system through a circuit breaker.

What does a current transformer look like?

A current transformer is a cylindrical device that is about the size of a quarter (25 mm) and has two terminals on one end. The CT has a high voltage terminal and a low voltage terminal. The terminals are connected to an alternating current supply or a direct current supply, depending on the type of transformer being used.

A CT can be installed in many different ways, depending on the type of transformer being used.

They can be installed outside of buildings or inside houses or offices. They may be installed directly into the wiring system between the voltage transformer and the wiring system, or they may be installed outside of the building’s wiring system but still in close proximity to it.

Components of a current transformer

A typical current transformer comprises different components that work together for the success of the device. Let’s look at each of these components and the role that they play.

Primary winding

The primary winding consists of two separate wires that run around the outside of the core. The two wires are insulated from each other and are connected to the low-voltage terminal and high-voltage terminal on one end.

Primary coil

The primary coil is made up of a few turns of wire that is wrapped around the core. The number of turns in this coil determines the amount of current it will pass for a given voltage.

Core

The core is made up of laminated steel laminations which form an air gap between them. This air gap acts as a magnetic field for inducing a magnetic flux in the secondary winding when current flows through the primary winding.

Secondary Winding

The secondary winding consists of a few turns of wire that is wrapped around the core. The number of turns in this coil determines the amount of voltage it will produce for a given current.

Secondary coil

The secondary coil is made up of a few turns of wire that is wrapped around the core. The number of turns in this coil determines the amount of voltage it will produce for a given current.

Secondary terminal

The secondary terminal is connected to the load. This terminal must be insulated from all other parts to prevent short-circuiting and ground loops.

This figure shows you how all these components are arranged together to form a complete transformer. Each component plays an important role in determining how well it works as one unit.

How does a current transformer work?

Since we have seen the different components let’s now have a look at the working principle of the current transformer (CT).

As we have seen from the definition, the primary role of the current transformer is to reduce the amount of high voltage currents to low currents. So how do the CTs achieve this goal?

In the primary circuit, there is a high voltage source connected to the secondary winding. The anode of this high voltage source is connected to the grid of the secondary coil. This high voltage source will produce a large amount of current in its primary winding.

Since there is no load on it, this current will flow through the primary coil and into the secondary coil.

This process will continue until it reaches the point where it meets its opposite polarity, which is equivalent to saying that it has reached a zero point because there are no other positive or negative voltages present anywhere else in that circuit.

The area where these voltages meet each other is called a node, which produces an electromagnetic field called an emf or magnetic flux.

To reduce the current flowing through the primary coil, we need to create a voltage difference between the anode of the high voltage source and the negative electrode of the secondary winding.

This can be done by putting a resistor in series with this circuit. Since this resistor will absorb some of the energy, it will create a voltage drop across it. This will result in less energy and less current being able to pass through and into the secondary coil.

Types of current transformers

Current transformers are not all the same. Here are the main types of current transformers.

Wound current transformer

This type of transformer has a primary coil and a secondary coil.

The primary coil is held by a spring. The secondary coil is wound around the primary and the two coils are connected together at the center of their respective coils.

The wire that connects these coils is called the winding. This winding is held by another spring which keeps it from unwinding.

The power used to wind the secondary coil can be supplied from either the primary or from an external source, such as an electric motor or generator (if there are no windings in the primary).

The winding in this type of transformer acts as a movable core that can be moved to change its magnetic field strength in relation to its surroundings. The higher its position, the stronger the secondary winding’s field is.

Toroidal current transformer

The toroidal current transformer is a special type of current transformer consisting of two concentric toroidal coils. The outer coil is wound with many turns, usually in the range of 10,000 to 50,000. The inner coil is wound in a smaller number of turns and serves as the core for the transformer.

The output voltage can be easily varied by simply moving one of the coils relative to the other within its own magnetic core.

Bar-type current transformer

A bar-type current transformer consists of two or more soft iron bars, such as a plate and a cylinder. The bars are separated by a gap and are connected to the primary and secondary windings in series. A gap is also provided between the bars to allow for the magnetic flux to pass freely from one bar to another.

Helical current transformer

The helical current transformer consists of two or more helix coils wound around a common axis, with a different number of turns on each coil. The coils are connected in parallel and brought close enough together for the magnetic flux to pass through them without much loss.

The voltage output is proportional to the number of turns in each coil multiplied by the length of each coil element.

What is the difference between a transformer and a current transformer?

A transformer is a device that converts electrical energy from one form to another. In contrast, a current transformer does not change the voltage, but simply changes the amount of current that it carries within itself.

What is the size of current transformers?

The size of the current transformers depends on the voltage and frequency of the applied voltage. The lower the frequency, the larger current transformers will be needed as a large number of turns is required. Similarly, at higher frequencies, a smaller number of turns will be required.

Hand-held current transformers

Hand-held current transformers are used in a variety of electronic applications. They are small and portable and can be used to measure the current drawn from batteries, charge batteries, or as a diagnostic tool. The current transformers are made up of a number of turns of wire wrapped around an iron core with the ends connected to terminals.

The core is made from iron powder coated with nickel or copper. The winding is wound on a mandrel that is cut to length. The winding is then wrapped around the mandrel and secured by soldering the ends together. A handle is attached to one end for ease of use and portability.

Technical specifications of current transformers

Before you buy current transformers, there are several technical specifications that you should consider. Let’s look at some of them:

– The core material: it must be of high quality. The current transformer should be able to withstand high temperatures, and the core must have good conductivity. The core can be made from iron powder coated with copper or nickel.

– The winding material: a copper or nickel wire is used for winding the current transformer.

– The number of turns: it is important that you check the number of turns in your current transformer before purchasing one. It must be suitable for your application and compatible with the battery that you are using.

– The insulation material: it is important to choose a good insulating material. The insulation must be able to withstand high temperatures without breaking down.

– The number of windings: the number of windings in the current transformer is usually 4 or 6. In some cases, you can find a current transformer with more than 6 windings.

– The voltage rating: it is important that you choose a current transformer with the right voltage rating for your application at hand.

– The power rating: this should be compatible with the battery that you are using. If you are using a battery with lower power output, then you should choose a smaller current transformer with a higher power rating to match it up. On the other hand, if you are using a battery with higher power output, then you should choose a larger current transformer with a lower power rating to match it up.

Where are current transformers used?

-In battery chargers: current transformers are used in battery chargers to change the current flowing through the charger. By adjusting the number of windings in a current transformer, you can adjust the voltage and power rating of the charging current.

-In solar panels: are used with solar panels to increase or decrease their output voltage. To do this, you must use a specific number of windings in your current transformer.

-In inverters: they are used in inverters to change the output voltage from an AC input voltage. The main purpose is to be able to charge batteries using AC input voltage but still have higher DC output power than a standard inverter.

-Electrical substations: current transformers are used in electrical substations to change the voltage going through the substation. By adjusting the number of windings in a current transformer, you can adjust the voltage and power rating of the substation.

-Power plants: they are used in power plants to change the voltage going through them. By adjusting the number of windings in a current transformer, you can adjust the voltage and power rating of the plant.

-In robotics: current transformers are used in robotics to increase or decrease their output voltage. In order to do this, you must use a specific number of windings in your current transformer.

Conclusion

I hope you have learned about current transformers, how they work and how to use them. I would like to point out that you should only use a current transformer if you need it, as they are very expensive.

I hope that this article has been helpful and if you have any questions, please leave a comment down below. Contact ICRFQ now.