JPH06289061A - Electric amount measuring instrument - Google Patents

Abstract

PURPOSE:To provide an electric amount measuring instrument in which connecting operability is improved and which has space conservation and a low cost. CONSTITUTION:A piezo element 4 is brought fixedly into contact with a power supply wire 1 connected to a load 2. When the wire 1 is vibrated by magnetostriction generated due to an AC current, the element 4 converts the displacement due to the vibration to an electric signal. This signal is converted to a digital value by an A/D converter 5 and displayed on a display unit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric quantity measuring device.

[0002]

2. Description of the Related Art Generally, an electric quantity measuring instrument that measures an electric quantity by using an electronic circuit has excellent characteristics over time because it has no mechanical moving parts and is easy to use for small-scale mass production. Development is being promoted as it can contribute to the reduction of

A conventional electric quantity measuring instrument of this type will be described by taking a current measuring instrument as an example. That is, one or, if necessary, a plurality of current transformers for converting a high current flowing through the power supply line into a low current is connected to the power supply line that supplies power to the load. The high-level current of the measurement system whose current has been reduced is sent to the current detector.

In the current detector, the high level current of the sent measurement system is converted by the current transformer into a low level current which can be processed by the internal circuit. This converted current is A /
It is converted into a digital value by the D converter, and the current value according to the used current is displayed on a display device composed of liquid crystal, LED, or the like.

[0005]

In such a conventional electric quantity measuring device, a large-scale current transformer is required to convert a high current flowing in the power supply line into a measurable current. Not only does it require installation space, but it is also expensive.

In addition, when connecting a current transformer for converting a high current flowing in the power supply line into a measurable current, or an electric quantity measuring device, it is necessary to cut the electric wire of the system to be measured once and then interpose them. Therefore, improvement of connection work was desired. An object of the present invention is to provide a low-cost electrical quantity measuring device that improves connection workability, saves space.

[0007]

In order to achieve the above object, the present invention provides a vibration-electric quantity conversion means for converting an electric signal proportional to the vibration of a power supply line into contact with the power supply line. Is the gist.

[0008]

In such a structure, the vibration-electricity conversion means arranged in contact with the power supply line converts the vibration due to magnetostriction generated in proportion to the current flowing in the power supply line into an electric signal, The converted electrical signal is sent to the electronic circuit in the subsequent stage, which is provided according to the amount of electricity you want to measure, so a large current transformer is not required and it is not necessary to disconnect the electric wire of the system to be measured during connection work. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a current measuring device according to an embodiment of the present invention. In the figure, 1 is a power supply line, which supplies power to a connected load 2. Reference numeral 3 is a current measuring device, and its vibration-electricity converting means, for example, a piezo element 4 is brought into contact with and fixed to the power supply line 1.

The piezoelectric element 4 outputs an electric signal proportional to the vibration when the element itself vibrates due to the vibration displacement based on the magnetostriction generated in proportion to the magnitude of the current (AC current) flowing through the power supply line 1. . The electric signal has a magnitude that can be processed by the internal circuit of the current measuring device 3, for example, a magnitude of several mA. Reference numeral 5 denotes an analog-digital converter (hereinafter referred to as an A / D converter) that converts an electric signal output from the piezo element 4 into a digital value (at this time, converts the AC current into an average value or an effective value). The value is displayed on the display 6.

According to the present embodiment, not only a large-scale current transformer is unnecessary and space can be saved, but also in the current measuring device 3, instead of the conventional current transformer, the piezo element 4 is used. Since it is used, it is small and can be made at low cost. Moreover, since it is only necessary to bring the piezo element 4 into contact with the power supply line 1 during the connection work, it is not necessary to cut the electric wire of the measurement circuit, and the connection workability is improved. Furthermore, when the current transformer is used as in the conventional case, power consumption occurs when driving the power supply line 1, but the piezo element 4 only detects the vibration of the power supply line 1 so that power consumption is reduced. It is economical because it disappears.

Next, FIG. 2 shows a block diagram of a power meter showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, reference numeral 8 denotes a voltage detector, which is composed of, for example, a voltage divider by a transformer or a resistor, detects a line voltage between the power supply lines 1 and converts it into a level that can be processed by an internal circuit. Reference numeral 9 denotes a multiplier, which is composed of, for example, a time division multiplication circuit, and multiplies the electric signal output from the piezo element 4 and the output signal from the voltage detector 8 to obtain a signal proportional to power. Then, the signal proportional to the power from the multiplier 9 is displayed on the display 6 via the A / D converter 5, and the power meter 7 is formed.

Further, as shown in FIG. 3, if an integrator 11 is connected to the stage after the multiplier 9, a value proportional to the amount of electric power can be obtained, and the value can be applied as the electric power meter 10. The integrator 11 is composed of, for example, a voltage-frequency converter or a counter.

As described above, the electric quantity measuring device of the present invention can be applied as an electric current measuring device, a wattmeter, or a watthour meter, and in any case, the effects as described above can be obtained. In addition, a transducer may be provided instead of the display device 6 to serve as a transducer, and an electrical quantity measuring device suitable for automatic meter reading may be provided.

[0015]

As described above, according to the present invention, the vibration-electricity converting means for converting into an electric signal proportional to the vibration of the power supply line is arranged in contact with the power supply line. It is possible to obtain a low-cost electricity quantity measuring device which has improved workability, can save space.

[Brief description of drawings]

FIG. 1 is a block diagram of a current measuring device showing an embodiment of the present invention.

FIG. 2 is a block diagram of a power meter showing a second embodiment of the present invention.

FIG. 3 is a block diagram of a power meter showing a third embodiment of the present invention.

[Explanation of symbols]

1 ... Power supply line, 4 ... Piezo element, 9 ... Multiplier, 11 ... Accumulator.

Claims (2)

[Claims] 1. An electric quantity measuring instrument comprising a vibration-electric quantity converting means for converting into an electric signal proportional to the vibration of the electric power supply wire, in contact with the electric power supply wire. 2. A vibrating-electrical quantity converting means arranged in contact with a power supply line for converting into an electric signal proportional to a vibration of the power supply line, and a voltage detector for detecting a line voltage of the power supply line. And a multiplier for multiplying the voltage signal from the voltage detector by the electric signal from the vibration-electric quantity conversion means.