CN113658783A - Medium-voltage low-frequency mutual inductor - Google Patents

Abstract

The invention discloses a medium-voltage low-frequency mutual inductor, which comprises a current-carrying conductor; a first terminal electrically connected to one end of the current carrying conductor; a second terminal electrically connected to the other end of the current carrying conductor; the sensor is sleeved outside the part between the two ends of the current-carrying conductor and is not contacted with the current-carrying conductor; and the insulating medium is arranged between the current-carrying conductor, the periphery of the Hall sensor, the current-carrying conductor and the Hall sensor. The current transformer can monitor medium-voltage (3-35 kV) direct current and low-frequency current such as low-frequency current in the frequency reduction control of a high-power motor, so that the problem that the medium-voltage direct current and the low-frequency current cannot be accurately monitored due to the fact that the existing current transformer is easily saturated is solved.

Description

Medium-voltage low-frequency mutual inductor

Technical Field

The invention relates to a medium-voltage direct-current power supply network and a medium-voltage variable-frequency power distribution and control system, which is used for monitoring direct current and low-frequency current, in particular to a medium-voltage low-frequency transformer.

Background

The existing medium-voltage (3-35 kV) distribution network has the frequency of 50Hz and is 60 Hz abroad, and the current under the condition is monitored by a current transformer generally manufactured by the traditional electromagnetic induction principle similar to a transformer; with the social development and the change of technical conditions, the requirements of high-voltage (3-10 kV) variable-frequency power distribution and control and medium-voltage direct-current power distribution relative to a mains supply (380V) system appear.

The requirement of the former is mainly for frequency reduction power distribution and control of a high-power and high-voltage (3-10 kV) motor, the main purpose is to enable the motor to be started and stopped stably, the impact on a power grid is small or even no impact is caused, and the energy-saving and protection device is embodied. For the current measurement and monitoring under the use condition that the frequency reduction is only a few hertz, the current transformer is easy to saturate, because the working magnetic flux density of the existing transformer is inversely proportional to the frequency, and the magnetic density margin for a magnetic conductive material in the design is very limited; once saturation occurs, the device cannot work normally and current is accurately monitored.

For the existing transformer, the direct current means that the frequency is 0, the transformer is certainly saturated, and the direct current cannot be monitored.

Hall sensors have long been commonly used as low-frequency and direct-current monitoring in low-voltage and electronic circuits, are relatively mature in principle and use conditions, but are not well used in the medium-voltage field, mainly because the insulation of the hall sensor cannot meet corresponding requirements.

Disclosure of Invention

The invention aims to provide a medium-voltage low-frequency transformer which can monitor medium-voltage (3-35 kV) direct current and low-frequency current such as low-frequency current in the frequency reduction control of a high-power motor, so that the problem that the medium-voltage direct current and the low-frequency current cannot be accurately monitored because the existing current transformer is easily saturated is solved.

The technical scheme of the invention for realizing the purpose is as follows:

a medium voltage low frequency transformer comprising:

a current carrying conductor;

a first terminal electrically connected to one end of the current carrying conductor;

a second terminal electrically connected to the other end of the current carrying conductor;

the Hall sensor is sleeved outside the part between the two ends of the current-carrying conductor and is not contacted with the current-carrying conductor;

and the insulating medium is arranged between the current-carrying conductor, the periphery of the Hall sensor, the current-carrying conductor and the Hall sensor.

The insulating medium is epoxy resin.

The insulating medium is insulating gas or liquid.

Further comprising:

a box body, the top surface of which is provided with an opening;

an insulating cylinder, the lower end of which is communicated with the opening;

an insulating plate sealing an upper end of the insulating cylinder;

the first terminal and the second terminal are arranged on the insulating plate, the current-carrying conductor and the Hall sensor are arranged in the box body, and insulating gas or liquid is filled in the box body.

The Hall sensor further comprises a shielding box for accommodating the Hall sensor.

The beneficial technical effects of the invention are as follows:

the Hall sensor is arranged in a medium-voltage low-frequency current loop by taking an insulating medium such as epoxy resin or SF6, transformer oil and the like as a packaging for strengthening insulation, and meets the insulation and related electrical performance requirements of medium-voltage grades under the limited space condition, so that the Hall sensor can monitor medium-voltage low-frequency current and direct current (0-400 Hz), and a novel product is formed.

Drawings

Fig. 1 is a schematic structural diagram of a medium-voltage low-frequency transformer according to the present invention.

Fig. 2 is a sectional view taken along line a-a of fig. 1.

Fig. 3 is a schematic structural diagram of another medium-voltage low-frequency transformer according to the invention.

Fig. 4 is a sectional view taken along line 3B-B.

Fig. 5 is a schematic structural diagram of a medium-voltage low-frequency transformer according to another embodiment of the present invention.

Detailed Description

The following examples are given to illustrate the present invention and it is necessary to point out here that the following examples are given only for the purpose of further illustration of the invention and are not to be construed as limiting the scope of the invention.

The description relating to "first", "second", etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Fig. 1 and 2 illustrate an embodiment of a medium voltage low frequency transformer among many embodiments of the present invention. The medium-voltage low-frequency transformer comprises a current-carrying conductor 1, an insulating medium 2, a Hall sensor 3, a first terminal 8 and a second terminal 9.

The current carrying conductor 1 is substantially U-shaped.

The first terminal 8 is electrically connected to one end of the current-carrying conductor 1. The second terminal 9 is electrically connected to the other end of the current carrying conductor.

The hall sensor 3 is ring-shaped, and is sleeved outside the part between the two ends of the current-carrying conductor 1 and is not contacted with the current-carrying conductor 1. In the embodiment shown in fig. 1 and 2, the hall sensor 3 is mounted on the U-shaped bottom section of the current-carrying conductor 1 without contacting the current-carrying conductor 1.

The insulating medium 2 is provided between the current-carrying conductor 1 and the hall sensor 3 and between the current-carrying conductor 1 and the hall sensor 3. In the embodiment shown in fig. 1 and 2, the insulating medium 2 is an epoxy resin, which serves as an insulating filling, forms a fixed structural part and doubles as a housing.

Fig. 1 and 2 present embodiments that also include a mounting insert 4, an operating power terminal 5 and a signal output terminal 6. The mounting insert 4 is used for the mounting fixing of the invention. The operating power supply terminal 5 is used to supply operating power to the hall sensor 3. The signal output terminal 6 is electrically connected to the hall sensor 3 for outputting an electrical quantity parameter signal proportional to the current flowing in the current carrying conductor 1.

When a medium-voltage level direct current or low-frequency current (0-400 Hz) flows through the current-carrying conductor 1 from the first terminal 8 and then flows out from the second terminal 9, a magnetic field is generated by taking a current flowing path as a center and is directly related to the magnitude of the current. The hall sensor 3 sleeved outside the current-carrying conductor 1 senses the size and the change of the magnetic field in the magnetic field, and outputs a small signal (only hundreds of milliamperes of current or only a few volts of voltage) corresponding to the size and the change of the magnetic field from the signal output terminal 6 to be supplied to a measuring instrument so as to identify the size of the current to be measured, thereby realizing the measurement of medium-voltage direct current or low-frequency current passing through the current-carrying conductor 1.

In the invention, the epoxy resin plays a role in enhancing insulation, and the limited space between the current-carrying conductor 1 and the Hall sensor 3 is used for meeting the requirement of corresponding voltage grade insulation. Meanwhile, the epoxy resin also serves as a support for fixing the respective members and also as an insulating case.

The embodiment presented in fig. 3, 4 differs from the embodiment presented in fig. 1, 2 in that: the embodiment presented in fig. 3 and 4 further comprises a shielding box 7 for accommodating the hall sensor 3, and the shielding box 7 can enhance the anti-electromagnetic interference capability of the present invention, so that the present invention has better performance. Otherwise, the embodiments presented in fig. 3 and 4 are the same as the embodiments presented in fig. 1 and 2.

Fig. 5 illustrates yet another embodiment of a medium voltage low frequency transformer among many embodiments of the present invention. The embodiment presented in fig. 5 differs from the embodiments presented in fig. 1 and 2 in that: the insulating medium 2 is insulating gas or liquid which plays a role in enhancing insulation, and the limited space between the current-carrying conductor 1 and the Hall sensor 3 is used for meeting the requirement of corresponding voltage-class insulation; the device also comprises a box body 10, an insulating cylinder 11 and an insulating plate 12; the top surface of the box body 10 is provided with an opening; the lower end of the insulating cylinder 11 is communicated with the opening of the box body 10; the insulating plate 12 seals the upper end of the insulating cylinder 11; the first and second terminals 8, 9 are arranged on the insulating plate 12, the current-carrying conductor 1 and the Hall sensor 3 are arranged in the case 1, and the insulating gas or liquid is filled in the case 1. Otherwise, the embodiment shown in fig. 5 is the same as the embodiments shown in fig. 1 and 2. The hall sensor 3 is supported by a holder 13 provided on the bottom surface of the case 1, and is provided in the case 1.

The shielding box 7 in the embodiment presented in fig. 3 and 4 can also be applied to the embodiment presented in fig. 5, and the shielding box 7 in the embodiment presented in fig. 5 is arranged in the same manner as the shielding box 7 in the embodiment presented in fig. 3 and 4, and will not be described here, specifically referring to the embodiment presented in fig. 3 and 4.

It should be noted that the various features described in the foregoing embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in any further detail in order to avoid unnecessary repetition.

The present invention has been described in detail with reference to the embodiments, which are illustrative rather than restrictive, and variations and modifications thereof are possible within the scope of the present invention without departing from the general inventive concept.

Claims (5)

1. A medium voltage low frequency transformer, comprising:

a current carrying conductor;

a first terminal electrically connected to one end of the current carrying conductor;

a second terminal electrically connected to the other end of the current carrying conductor;

the Hall sensor is sleeved outside the part between the two ends of the current-carrying conductor and is not contacted with the current-carrying conductor;

and the insulating medium is arranged between the current-carrying conductor, the periphery of the Hall sensor, the current-carrying conductor and the Hall sensor.

2. The medium voltage low frequency transformer according to claim 1, characterized in that said insulating medium is epoxy.

3. The medium voltage low frequency transformer according to claim 1, characterized in that the insulating medium is an insulating gas or liquid.

4. The medium voltage low frequency transformer according to claim 3, characterized in that it further comprises:

a box body, the top surface of which is provided with an opening;

an insulating cylinder, the lower end of which is communicated with the opening;

an insulating plate sealing an upper end of the insulating cylinder;

the first terminal and the second terminal are arranged on the insulating plate, the current-carrying conductor and the Hall sensor are arranged in the box body, and insulating gas or liquid is filled in the box body.

5. The medium voltage low frequency transformer according to any one of claims 1 to 4, characterized in that it further comprises a shielding box housing the Hall sensor therein.

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