Current Transformers
Current transformers are tools that are used to measure the current (or flow of electricity) in electrical transmission lines.
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Current transformers are important parts of power grid flow measurement. They can be found in large volumes on all power grids at specific intervals. They are also found mounted on homes and businesses for the purposes of measuring electricity flow. They are fitted with meters that can be easily read by utility workers. Because of the role current transformers play in the measurement and control of the flow of electricity, they are an essential part of all electricity control and access systems.
Understanding a current transformer requires an understanding of electrical current. Electrical current is measured in amperes, and one ampere is equal to the movement of 6.241 × 1018 electrons passed a given point per second. While power transformers control voltage, current transformers can measure and control movement for measuring purposes and help control the flow of electricity to electronic devices. Current transformers are used to obtain the measure of current in an AC power transducer. Current transformers also retain the ability to transform current to a value suitable for measurement or control. These transformers provide isolation and a step-down current output.
The simplest form of a current transformer consists of two coils of wire, electrically insulated from one another and arranged so that a change in the current in one coil (the primary) will produce a change in voltage in the other (the secondary). The transformers are designed to provide a current in its secondary, which is accurately proportional to the current flowing in its primary.
There are several types of current transformers including protective, measuring, air-gapped, anti-remanence, wideband, and linear current transformers as well as differing styles including split core and clamp-on current transformers. As is true with all other electricity control and measuring equipment, extra care must be taken when servicing or inspecting current transformers in order to avoid injury or equipment damage.
The accuracy and cost of current transformers depend on core materials. In a current transformer, the wire to be gauged is placed within the opening of the device and a measure of either alternating voltage or alternating current is produced.