Current Transformer Classification based on Four Parameters

One can discern parameters that define their use and function in the electrical circuit or the transformer’s circuit itself among the many features of transformers. We, therefore, identify several factors that characterize the based on the designation of the circuit and the circuit of the transformer for the current transformer classification.

Current transformer Classification

Current Transformer Classification based on circuit

This type of classification helps you to evaluate the functions performed by a specific circuit and can, therefore, be separated into three groups:
Power current transformers are designed to supply alternating current to various machine connections and modules, so it sometimes referred to as power current transformers. This category is the most popular of all accounting for up to 70 percent. These are commonly used to drive a wide range of loads: electric motors, appliances for homes, various amplifiers, rectifiers, lighting, and heating systems.

Pulse current transformers are used in separate sections of the electrical circuit to relay voltage and current pulses. A feature of these allows pulses of different duration, from microseconds to nanoseconds, to pass through themselves. Most often, the form of the impulse is rectangular, but any other is possible: triangular, sawtooth, bell-shaped, etc.

Current Transformer Classification based on Winding

In addition to the circuit designation, they are classified according to the transformer circuit and allow you to distinguish the following types:

Autotransformer winding

It is characterized by the fact that there is a magnetic and electrical connection between the primary (input) and secondary (output) winding. Taps from the common winding determine the primary and secondary winding.

Double-winding transformer

unlike a single winding transformer, with two winding that is electrically unconnected. This type of transformer is a basic and theoretical analysis is fundamental and the primary winding’s electrical parameters are uniquely related to the secondary winding electrical parameters.

Multi-winding transformers

It has several secondary windings that are electrically unconnected, the number of which exceeds ten, but most often four to five. In this type of transformer, several relationships with the current of secondary windings dictate the current of the primary winding is the most common type of transformer.

Current transformer Classification

Current Transformer Classification Based on Design Parameters

The transformer specification parameters specify the characteristics of their center and winding.

Building form.

One of the most important design features defining based on the design style. The determining factor here is the core form that can be described as:


The Unicore has three rods, the main rod wider than the extreme rods and the windings on it, and the side rods only serve for magnetic flux flow. The rectangular core has two rods of the same width and the windings are evenly placed on it.

Toroidal core,

Rendered in the shape of a rectangular toroid or (rarely) a circular cross-section, and the windings are evenly distributed throughout the core.

Types of Core.

This feature characterizes the transformer key manufacturing technology. It is possible to distinguish the following categories:

Laminated cores

The core assembly is from stamped plates of one type or another. However, another type of core is used due to the lack of manufacturability of stamping plates for high-power current transformers.

Wounded Cores

Cores of this kind are shaped or wound on machines from bent tape segments. They are locked, detachable, and split depending on the transformer’s assembly principle. Structural tapes vary only in the presence of rounded corners.

Powdered Core

By the name, both the core halves and their integral variant are made by pressing from powder materials. In connection with the need to use ferrite powder materials as magnetic cores of the corresponding structures, the need for pressed cores emerged. As almost any shape can be set by pressing, so many shapes are created in the form of cores.

Classification of Tactical and Technical Parameters

As transformers are most commonly used in electronic devices operating under different conditions, they are suitable for specific conditions and must, therefore, be defined.

Transformer scope.

This signature will determine the scope and requirements in this area:

Domestic applications.

They are characterized by insignificant operating conditions requirements under domestic (home) conditions and are used in broadcast equipment.

Commercial applications

This type usually works in measuring equipment, control equipment for different machines, etc.

Special applications.

As a rule, these are used in military and special-purpose equipment. The specifications for them depend on the specific area of use, and special-purpose transformers are classified into the following categories for use in equipment: onboard equipment (aircraft and missiles), ship equipment (for surface and submarine vessels), shore stationery equipment.

Service Life.

This element is related to the previous parameters since specific criteria are specified by the scope. The average time of use of the transformer in the on-state is known in the service life. It is possible to distinguish the following

Temperature Conditions

Temperature Conditions and transformer functions often depend on their application conditions. The following values are determined by these conditions:

  1. Ambient temperature
  2. winding operating temperature and
  3. Winding overheating.

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