CN205039036U - Wide -range current transformer - Google Patents

Abstract

The utility model provides a wide-range current transformer, wherein the structure of the transformer includes a primary winding, a secondary winding and an iron core, and the iron core is composed of a fixed iron core and a movable iron core, and the movable iron core is connected from the transformer The air gap is formed by pulling away; the structure is simple and easy to realize; when the primary current of the current transformer is large, the magnetization curve of the iron core can be placed in the linear region by adjusting the length of the air gap, which effectively solves the problem of increasing the error caused by the saturation of the iron core problem, reducing core loss.

Description

A Wide Range Current Transformer

technical field

The utility model belongs to the field of current transformers, in particular to a structure for widening the measuring range of the current transformer by changing the length of the iron core air gap.

Background technique

Current transformers are widely used in electric energy metering in the power generation, transmission, transformation, and distribution of power systems. They convert the large current on the primary side into a unified small current on the secondary side. The performance of the current transformer greatly affects the measurement and measurement and control. accuracy. Due to the great disparity of current in different locations and different time periods of the power grid, ranging from a few amps to tens of thousands of amps, in order to facilitate measurement, protection and control, current transformers often need to formulate different transformation ratios according to the range of the measured primary current. Make the secondary current within the specified range.

If core saturation is not considered, the ratio of the primary side current to the secondary side current is inversely proportional to the number of turns of the primary and secondary windings. Therefore, traditional current transformers often set multiple taps at different positions of the secondary winding, so as to select different transformation ratios for different measurement objects. However, in practice, due to the constraints of iron core materials and other factors, it is often difficult for a current transformer with a fixed iron core structure to ensure that its measurement operating point is in the linear region of the iron core flux density at the same time when the current transformation ratio is large and the current transformation ratio is small. , resulting in inaccurate measurement results and affecting measurement accuracy. Research and analysis shows that when the magnetic density of the iron core is too small or close to saturation, the operating point of the current transformer may enter the nonlinear characteristic area of the iron core, which not only distorts the secondary current waveform, but also affects the current amplitude. produce large errors.

Utility model content

In order to solve the above defects and deficiencies in the prior art, the utility model provides a wide-range current transformer, which can ensure that the magnetic flux density of the iron core does not exceed the saturation value when the primary current is maximum by adjusting the air gap length, and the iron core Features are always in the linear region.

In order to solve the above technical problems, the utility model provides a wide-range current transformer, which includes a primary winding, a secondary winding and an iron core. The iron core is composed of a fixed iron core and a movable iron core. The device is pulled away to form an air gap.

Preferably, the movable iron core includes at least one movable iron core unit, and the movable iron core unit is pulled away from the transformer to form an air gap.

Preferably, the number of movable iron core units is the number of measuring ranges of current transformers minus 1, wherein the number of measuring ranges of current transformers is at least two.

Beneficial technical effects achieved by the utility model: a wide-range current transformer proposed by the utility model has a simple structure and is easy to realize. When the primary current is large, the magnetization curve of the iron core can be positioned at In the linear region, the problem of increased error due to core saturation is effectively solved, and the core loss is reduced.

Description of drawings

Fig. 1 structural representation of the utility model current transformer;

Fig. 2 is a comparison diagram of the secondary current and primary current curves of the current transformer without air gap and the current transformer with air gap of the specific embodiment of the utility model.

detailed description

In order to better understand the technical features, technical contents and technical effects of the utility model, the accompanying drawings of the utility model are now described in more detail in conjunction with the embodiments.

Below in conjunction with accompanying drawing and embodiment the utility model patent is further described.

As shown in Figure 1, the utility model provides a wide range current transformer, including a primary winding 1, a secondary winding 2 and an iron core, the iron core is composed of a fixed iron core 3 and a movable iron core 4, and the movable iron core The length and number of 4 can be set according to actual needs, therefore, the length of the air gap 5 formed by the removal of the movable iron core 4 from the transformer is also changed, ensuring that the core magnetic flux density still does not exceed Saturation values, the core characteristic is always in the linear region. Preferably, the movable iron core 4 includes at least one movable iron core unit 40, so that different air gap lengths can be obtained when different numbers of movable iron core units 40 are removed, the structure is simple, and the operation is convenient.

Specific examples:

In order to verify the effect of a wide-range current transformer provided by the utility model, a current transformer with a non-air gap iron core structure and a current transformer with a certain air gap iron core structure proposed by the utility model were compared by using the finite element method Carry out modeling and simulation, in which the air gap length obtained by extracting the movable core unit of the current transformer with air gap core structure is 5mm, the comparison results are shown in Figure 2, compared with the non-gap core current transformer , using the iron core structure with a certain air gap proposed by the utility model, the linear region of the ratio of the secondary current to the primary current can be made wider, avoiding the saturation of the iron core when the primary current of the current transformer is large. brought about by the non-linear characteristics.

The utility model has been disclosed above with preferred embodiments, but it is not intended to limit the utility model, and all technical solutions obtained by adopting equivalent replacement or equivalent transformation schemes all fall within the protection scope of the utility model.

Claims (3)

1. a wide-range current transformer, is characterized in that: comprise winding, secondary winding and an iron core, described iron core is made up of secured core and movable core, and described movable core detaches formation air gap from instrument transformer.

2. wide-range current transformer according to claim 1, is characterized in that: described movable core comprises at least 1 piece of movable core unit, and described movable core unit detaches formation air gap from instrument transformer.

3. wide-range current transformer according to claim 2, is characterized in that: described movable core unit number is that current transformer range number subtracts 1, and wherein current transformer range number is at least 2.