3 questions - 3 answers

With Kastriot Alijaj

The job of a current transformer

Overall, current transformers play a crucial role in the safe and efficient use of electrical energy by providing critical information that is essential for the operation and maintenance of power grids and electrical systems.

What needs to be considered when choosing the right current transformer?

Kastriot, there are several decisive factors to consider when selecting a current transformer depending on the application. What are they?

Choosing the right current transformer depends on several key factors. Firstly, the maximum current that can flow through the transformer should be taken into account. This determines the size of the transformer and its load capacity. The dimensions of the conductors or copper rails to which the transformer is to be attached are also important to ensure that the transformer can be installed correctly. For new installations, it is particularly important to check whether the installation can be shut down during installation to route the conductors through the transformer or whether special installation procedures are required to maintain operation.

Another crucial point is the size of the transformer itself. It is important to ensure that the primary current and the opening of the transformer are not oversized in order to avoid unnecessary costs and space requirements.

What types of current transformers are there?

There are several types of current transformers that offer different advantages depending on the application:

Closed transformers (RX):
- Suitable for new installations, copper busbars and cables.
- Secondary current is always 5A.
- Advantages: Inexpensive, compact, can be permanently overloaded by 20%.
- Disadvantages: Cannot be opened.
- Available from 50A to 3000A.
Folding transformer:
- Suitable for retrofitting in distribution boards, measurements on copper busbars or conductors.
- Secondary current is always 5A.
- Advantages: Retrofitting without dismantling the copper busbar, good overload capacity.
- Disadvantages: Larger design.
- Available from 100A to 1500A.
Cable conversion transformer:
- Suitable for retrofitting, insulated conductors.
- Secondary current optionally 1A or 5A.
- Advantages: Can be opened for easy installation, pre-existing connection cable up to 3m.
- Disadvantages: Higher price, limited ability to extend connection cables.
- Available from 60A to 1000A.
Rogowski coils with transducer:
- Suitable for retrofitting to copper busbars or conductors.
- Compact design due to the flexible coil.
- Advantages: Enables measurement of several conductors simultaneously, adjustable primary current measurement.
- Disadvantages: Higher price, requires a measuring transducer with voltage supply.
- Measuring range from 100A to 4000A.

These different types each offer specific advantages and disadvantages that should be carefully considered depending on the requirements of your application. The right choice will not only ensure accurate current measurement, but also an efficient and cost-effective installation.

In today's world, energy management is not only a must, but also a clear competitive advantage.

What happens if the right current transformer is not used?

The incorrect selection of the current transformer The measuring accuracy and therefore also on the measured values that are ultimately displayed by the meter at the end. Incorrect measured values can, e.g. with load management for electric charging stations, for example, can lead to an unnecessary Reduce the charging power unnecessarily. In addition, the installation of an excessively current transformers that are too large is often a laborious task, as the transformer then hangs in the the system and cannot be fixed properly.

Thank you Kastriot for answering the questions.

If you would like to find out more about this topic, please contact us directly or watch our video on current transformers. We look forward to hearing from you.

The Optec team answers