Gearing Up For Improved Accuracy In Current Transformers

By Author: Rosario Berry
Total Articles: 179

Widely used in the monitoring of performance across the power grid, current transformers measure the value of primary current against a secondary current, in ratio. This type of transformer is generally used along with voltage transformers in a step-down manner, measuring the actual current of a primary feed. The accuracy of the measurement is vital for determining power use throughout the grid.

Accuracy Class

For the purpose of metering electricity usage and indicating the correct amount of electricity passing through to specific buildings within the power grid, it’s important for there to be an accurate measure of the ratio between primary and secondary currents measured by current transformers. The degree to which a transformer is accurate is expressed as its accuracy class.

Choosing Current Transformers

Frequently, we will find multiple current transformers stacked together accomplishing various tasks. Sometimes where revenue metering and protection devices are installed, separate transformers are used to isolate the two. These transformers have a variety of characteristics and can be specifically selected to match the particular burden expected, allowing for accurate measurement and monitoring at multiple points.

Transformer Uses

Supplying a reduced value of current to protective relays, revenue meters and other instruments, current transformers provide for the safer handling of the primary current by stepping down the magnitude of the current to be measured. The secondary current remains proportional to the primary current while being grounded for safety and being isolated from the main current.

Elements of a Transformer

Within a current transformer, there are two or more conductor windings, each existing on a magnetic core path. Rolled iron in sheets is treated to ensure that its magnetic conducting quality is high and that this permeates the whole core. The iron sheets are laminated to prevent the core from overheating. The primary coil wound around the core receives the energy. Designed for accuracy, there are only minor losses of energy between primary and secondary coil windings.

Stepping Down

The ability of current transformers to step-down current levels by thousands of amperes is the reason this type of instrument is crucial to accurate monitoring of the power grid. Reducing the level to 5 Amps or 1 Amp, small and accurate control devices can be used with transformers of this type. Insulated from high voltage power supply lines, these transformers allow for safe and easy handling of watt-power meters, protective relays and other useful instruments.

Innovations in Current transformers

Since this type of transformer is constantly under development and often customized for specific applications, there are frequently enhancements being made that substantially alter their capacity for accuracy. Transformers having heat radiation functions, including E-shaped cores, or being integrated with inductors are just some of the modifications allowing for higher accuracy and effectiveness.

About the Author:

Rosario Berry is a professional freelance writer, like to introduce Bumhan Co Ltd . Widely used in the monitoring of performance across the power grid, Current Transformers measure the value of primary current against a secondary current, in ratio.