JP2000088890A - Combined type current transformer device and measuring device for low voltage distribution line information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an erroneous wiring caused by overcrowding by packaging first and second current transformers in the same case with one zero-phase current transformer. SOLUTION: First and second current transformers 61, 62 are the ones for measuring a load current flowing in first and second terminal electric wires respectively. A zero-phase current transformer 63 is the one for measuring a leak current flowing in the first and second terminal electric wires and a neutral point electric wire. Since the first and second current transformers 61, 62 and the zero-phase current transformer 63 are packaged in a case made of a resin, a mounting work at a field can be simply carried out. Since the first and second terminal electric wires and the neutral point electric wire are connected to first to third terminals 11-13 respectively and first to third output terminals may be connected to input terminals of a watthour meter, an erroneous wiring cased by overcrowding can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current transformer, and more particularly, to a current transformer device used with a watt-hour meter attached to a consumer such as a home or a factory.

[0002]

2. Description of the Related Art As is well known, a high voltage generated by a power plant is transmitted to a secondary substation (distribution substation) via a primary transmission line, a primary substation, and a secondary transmission line. Here, the voltage is reduced to the distribution system. A primary distribution line (high-voltage distribution line) is drawn from the distribution substation, and the voltage is reduced by a distribution transformer connected to the primary distribution line. This distribution transformer is often installed on a telephone pole in Japan, so it is also called a pole transformer. A secondary distribution line is drawn from this distribution transformer (pole transformer). This secondary distribution line is also called a low voltage distribution line. That is, 200 to 1 to each customer via the secondary distribution line (low-voltage distribution line).
A voltage of 00 V is supplied (distributed).

[0003] As the above-mentioned distribution transformer, a core type single phase 3
Wire transformers are often used. That is, there are a two-wire system and a three-wire system in the single-phase AC system. In the single-phase three-wire system, generally, an electric wire is drawn from a neutral point in addition to the transformer secondary terminal. Therefore, in the case of a single-phase three-wire system, a low voltage is supplied to each consumer (home) via a low-voltage distribution line composed of three electric wires. Here, of the three wires, one wire drawn from the neutral point of the transformer is called "neutral wire", and two wires drawn from the remaining secondary terminals of the transformer are called "neutral wires". Each will be referred to as a "terminal wire".

As is well known, each customer is provided with an integrating wattmeter, and power is supplied to each customer via the integrating wattmeter. The integrating wattmeter is a measuring device for measuring the power consumed by each consumer, and is housed in a housing. Its structure consists of an aluminum disk, a voltage coil, a current coil and a metering device. The aluminum disk is rotated in proportion to the product of the magnetic flux of both coils, and the power is measured at the number of rotations.

[0005] By the way, there is a demand in power companies to measure and monitor information on low-voltage distribution lines for maintenance management of low-voltage distribution facilities. Nevertheless, under the present circumstances, as described above, only information on the power consumption measured by the integrating wattmeter installed in each home was obtained as information on the low-voltage distribution line for home use. .

On the other hand, a current transformer is generally used as one of means for measuring a current flowing in an electric wire.
Therefore, it is easy to attach the current transformer to the low-voltage distribution line in order to obtain information on the low-voltage distribution line.

[0007] In recent years, service and cost reduction have been demanded in power supply. In order to respond to this demand, the development of a "low voltage distribution line power monitoring system" is being promoted.
Here, the "low voltage distribution line power monitoring system" refers to remote centralized monitoring of facility information as efficient equipment operation, reliability improvement and service improvement in low voltage distribution lines distributed to consumers such as homes and factories. Refers to a system.

[0008] This system measures the load current (primary-side current / leakage current) of each home to perform appropriate power transmission and to monitor the load current. Also,
This system can improve services such as avoiding accidents by measuring ground fault current and leakage current.

This system is provided with a "detection device" that uses the primary side of the watt-hour meter as a measurement point. This detection device measures the current, voltage, and leakage current supplied to each home. That is, the detection device includes a current transformer (hereinafter, also referred to as “CT”) for measuring current, and a zero-phase current transformer (hereinafter, also referred to as “ZCT”) for measuring leakage current. The current measuring CT and the leakage current measuring ZCT are required to be suitable as power distribution equipment, such as installation in a small space, workability of mounting, and high accuracy of measurement.

[0010]

In the low-voltage distribution line power monitoring system described above, when it is desired to accurately measure and monitor information relating to the low-voltage distribution line, the above-described current measurement CT or leakage current measurement ZCT is used. Each of them is separately mounted to measure current.

Further, a current measuring CT and a leakage current measuring Z
If you try to use CT in combination,
There are the following problems. That is, for example, in the case of measurement at a lamp supply point by single-phase three-wire wiring, two current measurement CTs, one leakage current measurement ZCT, and a voltage measurement terminal are required. For this reason, workability is poor,
In addition, congestion occurs. Furthermore, since the output signals of the current measurement CT and the leakage current measurement ZCT are weak, if the output signals are directly transmitted via a cable, the measurement accuracy cannot be guaranteed.

[0012] As a prior art related to the present invention, Japanese Patent No. 2626789 discloses a method of laying in a distribution line to detect and display when a search signal current flows through the distribution line. `` Indicator for ground fault detection ''
Is disclosed. The ground fault point exploration display has a detection unit that detects a detection signal current flowing through a distribution line and outputs a detection signal, and a display unit that receives the detection signal and performs a display operation. The part is connected and integrated. However, this prior art merely discloses using a current transformer as a detection unit.

[0013] Accordingly, it is an object of the present invention to provide a system suitable for use as a detection device for a low voltage distribution line power monitoring system.
An object of the present invention is to provide a composite current transformer device.

Another object of the present invention is to provide a composite type current transformer device which can be easily mounted and can avoid wiring errors due to congestion.

Still another object of the present invention is to provide a composite current transformer device which can guarantee the measurement accuracy even if the measurement result is transmitted via a cable.

[0016]

The present invention employs the following technical structure to achieve the above object.

That is, according to the first aspect of the present invention,
A single-phase three-wire combined current transformer device for supplying power via a low-voltage distribution line composed of first and second terminal wires and one neutral point wire, comprising: a first and a second current transformer device; First and second current transformers for measuring load currents flowing through the first and second terminal wires, and one current transformer for measuring leakage current flowing through the first and second terminal wires and one neutral point wire. Wherein the first and second current transformers and one zero-phase current transformer are packaged in one case. .

The composite type current transformer device has a first
And first and second converters for converting the first and second detection signals from the second and second current transformers into DC currents, respectively.
And a third current signal conversion circuit for converting the third detection signal from the zero-phase current transformer into a DC current.

According to a second aspect of the present invention, a detecting device for measuring a load current and a leakage current of a low-voltage distribution line, and a power consumption supplied from the low-voltage distribution line via the output device A low-voltage distribution line information measuring device, comprising: a watt-hour meter for measuring the electric power, and housing the detection device and the watt-hour meter in one housing.

It is desirable to use the above-described composite current transformer device as the detection device.

[0021]

[Operation] Since two current transformers and one zero-phase current transformer are packaged, the connection point with the power equipment is one.
It is possible to avoid wiring errors due to congestion. Then, a large-diameter electric wire that passes through the inside of the current transformer and the zero-phase current transformer protrudes outside the package inside the package, and uses it as a rod terminal conforming to the watt hour meter standard to connect it to wiring equipment. I do. In addition, by converting the detection signals of the current transformer and the zero-phase current transformer into DC current by the current signal conversion circuit, signal attenuation and noise effects in the cable to the information processing device are suppressed, and transmission over longer distances is possible. You can do it.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, in order to facilitate understanding of the present invention,
An outline of a low-voltage distribution line power monitoring system to which the combined current transformer device according to the present invention is applied will be described.

The low-voltage distribution line power monitoring system is designed to improve the reliability of low-voltage distribution lines, increase work efficiency, and efficiently operate low-voltage distribution equipment. Information on low-voltage distribution lines (power failures, voltage fluctuations, load currents, transformers, etc.) It is a system for remote centralized monitoring of usage rate, high frequency, etc.). The low-voltage distribution line power monitoring system consists of a "central processing unit"
It is composed of three types of devices: a plurality of "pillar detectors" installed on a pole and a plurality of "consumer detectors" installed at a customer (customer). "Central processing unit"
Displays and stores information detected by each detection device and transmitted via a transmission system (transmission path, relay device). As the transmission system, a wired or wireless transmission system may be used, and any existing communication network or newly established communication network may be used.

The low-voltage distribution line power monitoring system has a "condition monitoring" function for monitoring equipment abnormality and a "remote measurement" function for measuring an electrical state. The measurement point is the secondary side of the transformer for pole use and the primary side of the watt hour meter for customer use. The detection device can measure voltage, current, and harmonics.
For harmonics, the total voltage distortion rate up to the 15th order is constantly measured.

The composite current transformer device according to the present invention is used as the above-mentioned "consumer detecting device", and includes a low-voltage distribution system comprising the two terminal wires and one neutral point wire described above. It is for a single-phase three-wire system that supplies power via electric wires. Further, as described later, it is preferable that the composite current transformer is used together with a watt hour meter (that is, it is arranged near the watt hour meter). In this case, the low-voltage distribution line does not directly supply electric power (low voltage) to each customer via the watt hour meter as in the related art, but via the combined current transformer device and the watt hour meter. Electricity (low voltage) will be supplied to each customer. Then, as described below, the watt hour meter and the composite current transformer device are housed in one housing.

As shown in FIGS. 7 and 8, a composite current transformer device denoted by reference numeral 10
Along with a watt-hour meter (integrated wattmeter) 20 indicated by 0, it is housed in a housing 30 indicated by reference numeral 30. The device in which the composite current transformer device 10 and the watt hour meter 20 are housed in the housing 30 in this manner will be referred to as a low-voltage distribution line information measuring device.

The composite current transformer device 10 is connected to a low-voltage distribution line composed of first to third electric wires 41, 42, and 43 drawn from the above-described distribution transformer (not shown). And third to third input terminals 11, 12, and 13, and first to third output terminals 16, 17, and 18. Of the first to third wires 41 to 43,
The first and second wires 41 and 42 are
And the third electric wire 43 is a neutral electric wire. Further, the first to third output terminals 16 to 18
Is connected to an input terminal (not shown) of the power meter 20 as a rod terminal. Further, the detection (measurement) result in the composite type current transformer device 10 is output signal cable 45
Is transmitted to the above-described information processing apparatus (not shown).

FIGS. 4 to 6 show the appearance of the composite current transformer device 10. FIG. 4 is a plan view, FIG. 5 is a front view, and FIG. 6 is a left side view. Composite current transformer device 10
Are housed in a resin case composed of a resin case body 50 and first and second resin case lids 51 and 52. More specifically, after the composite current transformer device 10 is housed in the resin case main body 50, the composite current transformer device 10 is covered with first and second resin case covers 51 and 52. As shown in FIG. 4, a connector 47 is attached to the end of the output signal cable 45, and is electrically connected to the information processing device.

Next, the internal configuration of the composite current transformer device 10 will be described with reference to FIGS.
FIG. 1 shows a first internal layout of the combined current transformer device 10 as viewed from the front, FIG. 2 shows a second internal layout of the combined current transformer device 10 as viewed from the front, and FIG. FIG. 2 shows a second internal layout of the type current transformer device 10 as viewed from a side. Note that the first internal layout diagram shown in FIG. 1 illustrates the layout on the back side, and the second internal layout diagram illustrated in FIG. 2 illustrates the layout on the near side.

As shown in FIG. 1, the composite type current transformer device 10 has first and second current transformers 61 and 62 and a zero-phase current transformer 63. The first and second current transformers 61 and 62 are for measuring the load current flowing through the first and second terminal wires 41 and 42, respectively.
Is for measuring the leakage current flowing through the first and second terminal wires 41 and 42 and the neutral wire 43.

More specifically, the first and second current transformers 61 and 62 and the zero-phase current transformer 63 are respectively
The first to third annular cores 611, 621, 631 and the first to third secondary windings (not shown) wound around the first to third annular cores 611 to 631 are provided. . Each of the first to third annular cores 611 to 631 is made of an iron core using a high magnetic permeability material. On the other hand, the first to third input terminals 11 to 13 are respectively connected to the first to third input terminals 11 to 13.
Of the internal wires 612, 622, and 632 are connected. First and second internal wires 612 and 6
22 penetrates through the through holes of the first and second annular cores 611 and 621, respectively, and the first to third internal electric wires 612 to 632, as shown in FIG. Through the through hole. And the first to third
The other ends of the internal wires 612 to 632 are drawn out to the outside as first to third output terminals 16 to 18, respectively.

If the above-described first and second current transformers 61 and 62 and the zero-phase current transformer 63 are individually mounted, an enormous number of man-hours are required. is there. In addition, wiring errors due to congestion cannot be avoided.

On the other hand, in the present embodiment, the first and second current transformers 61 and 62 and the zero-phase current transformer 63 are packaged in the resin cases 50 to 52. Installation work can be done easily. Also, the first to third input terminals 11 to 13 are respectively connected to the first input terminals 11 to 13.
And second terminal wires 41 and 42 and neutral wire 43
, And the first to third output terminals 16 to 18 need only be connected to the input terminals of the watt hour meter 20, so that wiring errors due to congestion can be avoided.

The first and second current transformers 61 and 62 and the first to third secondary windings of the zero-phase current transformer 63 are connected to a current signal converter 70 shown in FIG. A total of six signal lines 80 are drawn out of the current signal converter 70 and are electrically connected to the output signal cable 45. The current signal converter 70 converts the first to third detection signals from the first and second current transformers 61 and 62 and the zero-phase current transformer 63 into first to third DC currents, respectively. Things.

That is, since the first to third detection signals are weak signals, these signals are directly
If the signal is transmitted via the output signal cable 45, the measurement accuracy cannot be guaranteed. In order to prevent this, in the present embodiment, the first to third detection signals are respectively converted into first to third DC signals by the signal current converter 70 and transmitted through the output signal cable 45. are doing. As a result, it is possible to suppress the effect of signal attenuation and noise in the output signal cable 45 up to the information processing device, and it is possible to transmit a longer distance.

It should be noted that the current signal converter 70 is actually the first and second current transformers 61 and 62.
And first ends respectively connected to both ends of the second secondary winding.
And a second current signal conversion circuit, and a third current signal conversion circuit connected to both ends of the third secondary winding of the zero-phase current transformer 63. However, since the first to third current signal conversion circuits have substantially the same configuration, only the first current signal conversion circuit will be described below.

FIG. 9 shows a configuration of a first current signal conversion circuit indicated by reference numeral 71. First current signal conversion circuit 71
Is supplied with a first detection signal and a power supply voltage from the first current transformer 61. First current signal conversion circuit 7
1 outputs a first DC signal from two signal lines 81 and 82.

The first current signal conversion circuit 71 includes a load resistor 91, first and second protection circuits 92 and 93,
It comprises an AC amplifier circuit 94, a rectifier circuit 95, and a VI conversion circuit 96.

The first detection signal supplied from the first current transformer 61 is converted into a first detection voltage by the load resistor 91 and supplied to the AC amplifier circuit 94 via the first protection circuit 92. You. On the other hand, the power supply voltage is supplied to the AC amplification circuit 94, the rectification circuit 95, and the VI conversion circuit 96 via the second protection circuit 93.

The AC amplification circuit 94 includes a first protection circuit 92
AC-amplifies the first detection voltage protected by
Is output. The rectifier circuit 95 rectifies the first AC-amplified signal and outputs a first rectified signal. The VI conversion circuit 96 converts the first rectified signal into a first DC current. The first DC current is supplied to two signal lines 81 and 82 and an output signal cable 45.
Is transmitted to the information processing device via the.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The size of the composite type current transformer device 10 is 90.times.50.times.90 [mm] in width × height × depth.

[0044]

As described above, by using the composite current transformer device of the present invention, it is possible to easily install it on the integrating wattmeter. In addition, since the detection signals from the current transformer and the zero-phase current transformer are converted to DC current and transmitted, the measurement results of the current transformer and the zero-phase current transformer can be transmitted over a long distance without attenuation. It becomes possible. Further, by using the combined current transformer device according to the present invention as a detection device of a low-voltage distribution line power monitoring system, a "condition monitoring" function for monitoring equipment abnormalities in a home and a "remote measurement" for measuring an electrical state. "
An efficient system having functions can be provided.

[Brief description of the drawings]

FIG. 1 is a first internal layout view of a combined current transformer device according to an embodiment of the present invention as viewed from the front.

FIG. 2 is a second internal layout view of the composite current transformer device as viewed from the front.

FIG. 3 is an internal layout view of the composite current transformer device as viewed from a side.

FIG. 4 is a plan view showing the appearance of the composite current transformer device.

FIG. 5 is a front view showing the appearance of the composite current transformer device.

FIG. 6 is a left side view showing the appearance of the composite current transformer device.

FIG. 7 is a front view showing a low-voltage distribution line information measuring device including the combined current transformer device and a watt hour meter.

FIG. 8 is a side view showing a low-voltage distribution line information measuring device including the combined current transformer device and a watt hour meter.

FIG. 9 is a block diagram showing a configuration of a current signal conversion circuit used in the composite current transformer device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 combined current transformer device (detection device) 11 to 13 input terminal 16 to 18 output terminal 20 watt hour meter 30 housing 41 to 42 low-voltage distribution line 45 output signal cable 50 to 52 resin case 61, 62 current transformer (CT ) 63 Zero-phase current transformer (ZCT) 611 to 631 Ring core 612 to 632 Internal electric wire 70 Current signal converter 71 Current signal conversion circuit 80 Signal line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kotaro Sasaki, Inventor 6-7-1, Koriyama, Taishiro-ku, Sendai, Miyagi Prefecture Tokin Co., Ltd. (72) Inventor Yoshiyuki Goto 7-7-1, Koriyama, Tashiro-ku, Sendai, Miyagi No. Tokinnai Co., Ltd. (72) Inventor Naoki Wakuo 7-7-1, Koriyama, Taishiro-ku, Sendai, Miyagi Prefecture Tokinnai Co., Ltd. Within Electric Power Co., Inc. (72) Inventor Yukihiro Izumo 3-9-1, Amedori, Izumi-ku, Sendai, Miyagi Prefecture Within Token Electric Industry Co., Ltd. F-term (reference) 2G025 AA03 AB14 AC04 5E081 AA05 AA12 CC12 DD01 DD25 EE13 GG05

Claims (5)

[Claims] The first and second terminal wires (41, 4)
2) A single-phase three-wire combined current transformer device (10) for supplying power via a low-voltage distribution line composed of 2) and one neutral wire (43), First and second current transformers (61, 62) for measuring load currents flowing through the second terminal wires, respectively, and leakage flowing through the first and second terminal wires and the one neutral wire. One zero-phase current transformer (63) for measuring a current, wherein the first and second current transformers and the one zero-phase current transformer are in one case (50 to 52) A composite current transformer device characterized in that it is packaged inside. 2. Each of the first and second current transformers and the one zero-phase current transformer are annular cores (611, 621, 631) made of an iron core using a high magnetic permeability material.
And a secondary winding wound around the annular core. Internal electric wires (612, 622, 63
2. The device according to claim 1, wherein 2) is penetrated.
2. The combined current transformer device according to item 1. 3. A first and a second current signal conversion circuit for converting first and second detection signals from the first and second current transformers into DC currents, respectively, and the zero-phase current transformer. A third converter for converting the third detection signal into a DC current
3. The composite current transformer device according to claim 1, further comprising a current signal conversion circuit. 4. A detecting device (10) for measuring a load current and a leakage current of a low-voltage distribution line, and a power amount for measuring a used power supplied from the low-voltage distribution line via the detecting device. A low-voltage distribution line information measuring device, comprising a meter (20), wherein the detection device and the watt-hour meter are housed in one housing (30). 5. The low-voltage distribution line information measuring device according to claim 4, wherein the detecting device uses the combined current transformer device according to any one of claims 1 to 3. .