A current transformer
(CT) is a type of electrical transformer that is used to measure alternating current (AC) in an electrical power system. CTs are typically used to provide a reduced current signal to a metering or protective devices, such as an ammeter, relay, or control system.
The CT consists of a primary winding that is connected in series with the electrical conductor carrying the current to be measured, and a secondary winding that provides a reduced current output. The ratio of the primary winding to the secondary winding is referred to as the current transformation ratio (CTR), and it determines the magnitude of the reduced current output.
The CT is designed to be highly accurate and linear so that the reduced current output is proportional to the current in the primary winding. This enables the CT to provide accurate readings of the current in the electrical power system, even when the current is changing rapidly.
CTs are commonly used in a variety of applications, including electric power metering, protection of electrical equipment, and measurement of electrical power in renewable energy systems. They are available in a variety of configurations, including split-core, window-type, and toroidal CTs, to suit different installation requirements.
Features of a current transformer:
High accuracy: Current transformers
are designed to provide highly accurate current measurements, which is critical for maintaining the stability and reliability of power systems.
Wide measurement range: Current transformers are available with a wide measurement range, allowing them to be used for a variety of applications, from low-current to high-current systems.
Isolation: Current transformers are designed to provide electrical isolation between the primary and secondary circuits, which enhances safety and reduces the risk of electrical shock.
Robust construction: Current transformers are typically constructed from high-quality materials, such as aluminum or other metals, which provide durability and long-lasting performance.
Compact size: Many current transformers are designed to be compact, making them easy to install and use in a variety of applications, from industrial power systems to residential electrical systems.
Easy installation: Many current transformers are designed for easy installation and can be integrated into existing power systems without the need for major modifications or upgrades.
Types of current transformers:
Window-Type CTs: These CTs have a split-core design, allowing them to be easily installed around an existing conductor.
Bar-Type CTs: These CTs have a cylindrical shape and are typically used in low-current applications.
Rogowski CTs: These CTs have a flexible coil that can wrap around a conductor, making them well-suited for measuring current in irregularly-shaped conductors.
Wound CTs: These CTs have a primary and secondary winding that are wound onto a core, making them well-suited for high-current applications.
Split-Core CTs: These CTs have a split core that can be opened and closed, allowing them to be easily installed around an existing conductor.
Toroidal CTs: These CTs have a toroidal core, which provides high accuracy and low magnetic leakage.
Burden CTs: These CTs are designed to be used with a specific burden, or load, to provide accurate current measurements.