Types and Applications of Current Transformer

Current Transformers play a crucial role in power systems by converting high current into low current, ensuring the safe operation of measuring and protection devices. This article will delve into the types of current transformers and their wide applications.

Types of Current Transformers

Classified by Installation Method

Types of current transformers are numerous. Based on different installation methods, they can be categorized as follows: through-type current transformers, post-type current transformers, bushing-type current transformers, and busbar-type current transformers. The through-type current transformers are used to pass through panels or walls, while post-type current transformers can also serve as supports for primary circuit conductors. Bushing-type current transformers are directly mounted on insulated bushings, suitable for spaces with limited room. Busbar-type current transformers are used for direct installation on busbars, providing efficient and accurate current measurement for power systems.

Classified by Purpose

Based on their purpose, current transformers can also be divided into two main categories: measuring and protective types. Measuring current transformers are mainly used to provide grid current information for measurement and metering devices within the normal working current range; protective current transformers provide fault current information to relay protection devices during grid faults. This classification ensures the applicability and safety of current transformers in different situations.

Classified by Insulating Medium

Current transformers can also be categorized based on their insulating media. Common insulating media include dry-type, cast-type, oil-immersed, and gas-insulated. Dry-type current transformers use general insulating materials and are suitable for indoor use. Cast-type current transformers are formed using epoxy resin or other resin materials, offering good insulation performance. Oil-immersed current transformers are widely used outdoors, using insulating paper and oil as insulating media. Gas-insulated current transformers achieve insulation through gas and are suitable for special situations.

Applications of Current Transformer

Current transformers are widely used in power generation, transformation, transmission, and distribution processes. During these processes, due to the diversity of electrical equipment, current sizes range from tens of amps to tens of thousands of amps, and these circuits may also be accompanied by high voltage. In these scenarios, current transformers play a crucial role by proportionally converting high current to low current, enabling monitoring and measurement of the circuits. Additionally, current transformers feature electrical isolation, effectively ensuring the safety of measuring devices and operators.

Current transformers have core functions in current transformation and electrical isolation. The primary winding is usually made of thick wire with only one or a few turns, connected in series with the load of the measured current. The secondary winding is connected to measuring devices, and the size of the secondary current is entirely determined by the load current of the measured circuit, unaffected by the primary current. To ensure safety, the secondary side of current transformers must be reliably grounded to prevent high voltage from being transmitted to the secondary side in case of insulation breakdown, causing accidents. Moreover, the secondary side of current transformers should not be open-circuited; otherwise, it may lead to equipment damage or high voltage electric shock hazards.

Through the above introduction of the types and applications of current transformers, we believe everyone has a deeper understanding of this important device. Current transformers play an irreplaceable role in power systems and have vast application prospects in the future.

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