Classification of Current Transformers

Current transformer by insulation medium classification

1. Dry-type current transformer: by ordinary insulating material by dipping paint treatment as insulation.

2. Cast current transformer: the current transformer with epoxy resin or another resin mixed material casting molding.

3. Oil-immersed current transformer: insulated by insulating paper and insulating oil as insulation, generally for the outdoor type.

4. Gas-insulated current transformer: the main insulation consists of gas.

Current transformer classification according to the installation method

1. Through the current transformer: used to pass through the screen plate or wall current transformer.

2. Pillar type current transformer: installed in the plane or pillar, and do the primary circuit conductor pillar with the current transformer.

3. Casing type current transformer: no primary conductor and primary insulation, directly set on the insulated casing of a current transformer.

4. Busbar type current transformer: no primary conductor but has primary insulation, directly set on the busbar use of a current transformer.

Current transformer according to the principle of classification

1. Electromagnetic current transformer.

A current transformer that realizes current conversion based on the principle of electromagnetic induction.

2. Electronic current transformer.

For example

(1) Optical current transformer refers to the use of optical devices as the measured current sensor, and the optical devices are composed of optical glass, all-fiber, etc.

(2) Hollow coil current transformer, also known as Rogowski coil type current transformer. A hollow coil is often made of enameled wire evenly wound in the ring skeleton, the skeleton is made of plastic, ceramic, and other non-ferromagnetic materials, its relative permeability and the relative permeability of air, which is a hollow coil are different from the current transformer with an iron core of a distinctive feature.

(3) Iron core coil type low power current transformer (LPCT), which is a development of the traditional electromagnetic type current transformer.

Its design is according to the high impedance resistance, the saturation characteristics are improved at very high primary currents, expanding the measurement range and reducing power consumption.

It can measure overcurrent up to short-circuit current and full offset short-circuit current with high accuracy without saturation. Measurement and protection can share a core-coil type low-power current transformer, and its output is a voltage signal.