Field of Invention

This invention relates to the current transformer performing the functions to measure and protect the current in the high-tension wire of over lOkV.

Background and purpose of the Invention

The current transformer measuring the current in the high-tension wire is very important equipment in operating and controling the electric power system.

The current transformer of electromagnetic induction has merits of simple making and high reliability, but it has limitations of requiring a large volume ofjnsulating material, copper, piercing mandrel, insulator, and materials for outer cases essentially and being equipped with install structure certainly.

And when using, it has also deadly weak points that the 1 ^st and 2 ^nd coiling short-circuit by dielectric breakdown can make a ground fault accident of the system.

The current transformer using laser beam has merits of hardly using copper, piercing mandrel, and insulators, and never having system accident by transformer destruction which is the main fault of induction current transformer and it ensures the high insulation. The current transformer using laser beam has merits of hardly using copper, piercing mandrel, and insulator, and never having the system accident by transformer destruction which is the main fault of induction current transformer, and it can keep high insulation.

But, as making and installing a laser generator, a declinometer, a sensor and etc are complicated and install structure should be made and installed, it has not overcome the fault to be dampened.

The current transformer used Rogowski coil has a merit that making a sensor is uncomplicated like a new type of photocurrent transformer because it is using induction coil as a sensor.

And, it has also merits of hardly using copper, piercing mandrel, and insulator and never having a system accident by transformer destruction

But, it has not overcome greatly the limitations of surely having a laser beam generator, making an install rack, and having and an install place which are involved by beam current transformers. Even in the earlier patent documents (WO 201 1078096 A2, WO 201 1085517 A2, WO 2011142483 A2, WO 201 1161129 A2, WO 2012029524 A2) of electronic current transformer, current sensors are designed to be made complicatedly and entail higher costs.

It is said that the high-tension power unit in the electronic current transformer shown in WO 201 1085517 A2 main keeps up the power source in every section of measurement by self-exciting method, but it is designed not to keep up the power source in the section (OA-25 A) with very low high-tension.

US Patent No. 4052685(IPC H01 F 27/10,Oct.4.1977) refers to the current transformer of electromagnetic induction and this proposal essentially requests lots of oil insulator and insulators, too.

The purpose of this invention is to provide the electronic current transformer with high exactness, low cost, and little labour in repairing, installing, carrying and controlling by overcoming faults of current transformers mentioned the above.

Description of Invention

The invention relates to making the current transformer which is the equipment to measure and protect the current in the high-tension wire of over lOkV, to suspend directly in the high-tension wire.

This invention consists of sensor part (1) suspended in the high-tension wire (over 60kV) (5), signal-processing part installed in the cabinet panel (8), and communication part (3). Communication part consists of infrared sensor (4) sensing infrared signal got out of sensor part and signal cable (3) (figure 1), or fibre-optic cable (3) (figure 2) directly connected to sensor part.

The sensor part suspending in the high-tension wire is able to suspend directly in the high-tension wires for every voltage of over lOkV with about 15 centimetres in diameter, 35 centimeters in length, and 35 kilogrames in weight.

Distance between sensor part suspended in the high-tension wire, and infrared sensor differs according to voltage step, but it keeps full insulation as the distance is 0.5 metres in 10 kV and 1 metres in 60kV.

In case of keeping signal communication and insulation with fibre-optic communication, to be for the outdoors, it is installed by suspending the circular wings of 15 centimetres in diameter and about 0.5 centimetres in thickness and the tube-type silicon rubber insulator which the circular wings of 7 centimetres in diameter and about 0.5 centimetres in thickness are installed alternately with each other at regular intervals (about 5 centimetres) to sensor part and passing fibre-optic communication through this rubber insulator.

The sensor part installed suspending in the high-tension wire sends as infrared rays, or fibre-cable signal to signal-processing part by converting the current signal which has been sensed by the induced minimum current transformer with the ireon core of 7 centimetres in diameter and 2 centimeters in thickness, and protection signal as 1 Hz to about 1/2000 of resolution into real time A D, and thereafter the sinal-processing part functions displaying the current value, and protection.

This invention uses as the current transformers functioning the measurement of current and protection in all the high-tension wirees for every voltage of over lOkV.

The suspension electronic current transformer mentioned in this invention has merits as follows:

(Ϊ) comparing with other induction current transformer or electronic current transformer, it making is easy and its making is very inexpensive.

(D comparing with other induction current transformer or electronic current transformer, it is convenient for installation and transportation as its weight and volume are small, so it costs very little.

(D comparing with other induction current transformer or electronic current transformer, its repairing and keeping cost verty little.

(4) comparing with other induction current transformer, its exactness is high and there's no case of spreading the accidents at the time of the current transformer destruction.

(5) suspension electronic current transformer has a merit of having a high-tension power unit which keeps up enough power source even in very low 1 ^st current (1A-25A) comparing with other electronic current transformer.

Description of Figures

Figure 1 shows the installation of suspension electronic current transformer used tinfrared communication. The sensor sensing infrared signal sent out of the sensor part can be easily installed into equipment or structure such as transformer, breaker, pylon or etc.

Figure 2 shows the installation of suspension electronic current transformer using fibre-optic communication, into the interior. It keeps a certain degree of insulation by suspending fibre-optic cable without conducting substance from the sensor part and transmits signal to singal-processing part by normal fibre-optic cable. Figure 3 shows the installation of suspension electronic current transformer using fibre-optic communication installed at the outside. It keeps insulation for wet flashover by putting through-type insulator of silicon rubber to fibre-optic cable without conducting substance suspending at the sensor part.

Figure 4 shows the configuration of sensor part suspended at the high-tension wire. It consists of a sensor of current signal (1), a sensor of protection signal (2), a small induction current transformer (3) for high-tension power source, and signal-processing part of high-tension (4) strained the one-chip processor.

Figure 5 shows the main configuration of suspension electronic current transformer. It keeps high-tension insulation for every voltage of over lOkV with infrared signal or fibre-optic communication.

Figure 6 shows the high-tension power unit of suspension electronic current transformer. It keeps safe power source of 5V fully using 2 induction current transformers which secondary number of turns and area of shearing core.

Description of application examples of invention

The suspension electronic current transformer shown in Figure 1 consists of a sensor part (1) suspended in the high-tension wire, the communication part (3) sending the numeral signal out of sensor part to signal-processing part (2), and the signal-processing part (4).

The infrared signal sensor (4 in figure 1) which senses the infrared signal sent out of the infrared transmitting device (6 in figure 4) of sensor part is installed at the location (noninterferential with infrared signal of other phase) over 0.5~7m (according to voltage step of high-tension wire, higher voltage is, bigger it is decided) depart from the sensor part (1). At this time, the infrared signal sensor can be fixed to the main body of the structure like a transmitter, a breaker, or pylon.

The current signal (or protection signal) sensed by the current sensor (1 in figure 4), or protection signal sensor (2 in figure 4) of sensor part (1 in figure 1) installed in the high-tension wire transmits to the signal-processing part (4 in figure 4) with an one-chip processor through communication part by receiveing for high-tension processor (4 in figure 4) with an one-chip processing part and converting as a numeral signal.

As shown in figure 4, the high-tension processor (4 in figure 4) with a one-chip processing part is fixed inside the high-tension field of 10 cm in high-tension wire.

In order to protect the high-tension processor (4 in figure 4, circuit controlling high-tension power source, AJD converting circuit, circuit of infrared transmission and fibre-optic communication) contained the one-chip processing part from the electromagnetic field arised by the abnormal state like the high-tension electromagnetic field for every voltage of over lOkV and lightning current, double shielding method is applied.

The signal-processing part received this signal and functions displaying and transmitting (or protecting).

In case of using optical fibre in the communication part, as shown in figure 2, fibre-optic cable is installed directly between sensor part and signal-processing part. In this case, as shown in figure 3, to install the suspension electronic current transformer at the outside, silicon rubber through insulator is covered in some sections of fibre-optical cable from sensor part.

The high-tension power unit which keeps up power source of high-tension signal processing part is self-exciting method in every section of 1 ^st current measurement but it is comprised wholly different from WO 2011085517 A2.

In WO 201 1085517 A2, two transformers are used by a method of reinforcing electric power of power source when the 1 ^st current is small. But doing like this can not keep enough power source in the section (0A-30A) which the 1 ^st current is low regardless of the 1 ^st rated current measured. ,

In this invention, in order to measure rightly even in the section (0A-30A) which the 1st current is low, electric power of power source is kept by using 2 electromagnetic induction current transformer with different cross-sections (Q1>Q2) and different sencondary numbers of turns (L1>L2). Here, power source has been controlled by CPU. When the 1st current is lower that 40A, electromotive force of current transformer 1 is used, and when higher, the current transformer 2 is used.

Also, designing the amount of consumption of high-tension signal processing part and communication par at the lowest is the key fact to keep enough power source in every section of measurement.