All current transformers operate in a similar fashion. They are designed to include a primary and a secondary winding around a core. The core can be made of several different options in materials, and there are specific designs of current transformers that use an air core.
The Use of Current Transformers
A high voltage current transformer, as the name implies, is used to meter and to monitor high voltage systems. It is also used to protect the system, transforming the high current that is present on the high voltage side of the system into a low current that can be used with specific types of instruments on the low current side of the transformer. This prevents damage to the equipment, which can include relays or recorders as well as other types of measuring instruments.
This reduction in the current allows for effective monitoring and metering for AC lines by reducing the high voltage current to something of a much lower value, but that still allows accuracy in measurement.
The design of the high voltage current transformer is different from other types of transformers, with only a few turns on the primary winding. The secondary winding is more substantial with a greater number of windings to allow for the step down required.
In electric grids and power systems, the high voltage current transformer is an essential part of the system. These transformers may be designed with several cores to perform different roles within the electrical systems from protection to actually metering of the circuits.
In most applications, customization of these types of transformers to meet the needs of the system is an important consideration. There are also standardized transformers available that may have various options in the design. This can provide a lower-cost option than a full custom transformer but still provide all the features required for the given application.