JPS5940174A - Current measuring device - Google Patents

Abstract

PURPOSE:To realize easy and convenient measuring operation, by switching automatically a current for calibration and that for measurement, and recording reference amplification for the calibration and the current amplitude for the measurement on the same recording screen alternately and synchronously. CONSTITUTION:When an external signal START arrives, an oscillator 1 oscillates with a 10ms duty cycle to drive a relay K13. A monostable multivibrator 2, on the other hand, drives a relay K24 in 200ms to control a reference power source 5 for the calibration. Therefore, the contact 3-1 of the relay K13 and the contact 4-1 of the relay K24 are connected to the output side of the reference power source 5 for calibration for 200ms to input a signal to an AMP6. The relay K24 stops operating 200ms after the signal START and the input to the AMP6 is switched to the output of a shunt resistance SH9 by the contact 4-1. Assuming that a shunt resistance outputs 50mV when a 30A current flows, the outut of the resistance SH9 is equivalent to the amplitude value of the calibration reference power source 5 recorded on the recording paper of a photocoder 7 when the 30A current flows through the shunt resistance SH9. Consequently, the need for calibrating operation before load current measurement is eliminated and variance of the recorder (photocoder, etc.) is disregarded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for measuring a current value supplied from a power source to a load.

[Technical background and problems of the invention]

Conventionally, for example, the current value supplied from an AC power source (
To record ACfli (hereinafter referred to as current), a shunt resistor or the like was inserted into the circuit, and the voltage value generated there was read and recorded. In order to obtain the amplitude value, it was necessary to amplify the voltage generated by the shunt resistor, and it was necessary to convert the amplitude value into a current. Therefore, when performing these measurements, it is necessary to prepare a reference source for current/voltage conversion of the shunt resistor and record and calibrate the amplitude value of the photocoder in advance.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a current measuring device that eliminates the above-mentioned conventional troubles and simplifies measurement operations.

[Summary of the invention]

In the present invention, the conventional pre-calibration and current call
The same achievement was achieved by automatically switching between the settings and the KL.

[Embodiment of the Invention] FIGS. 1(a) and 1(b) show circuit diagrams of an embodiment of the present invention. As shown in the figure, (1) is 1' with a short pulse width.
O] 713 (when the AC power supply is 50 Hz), the first signal generator (oscillator), (2) is an integer multiple of the
There is a second signal generator (mono multivibrator) with ξ pulse width, both S'I'AJ? Triggered by T signal.

+31, +4) are first and second relays, for example mercury relays, the first relay (3) controls the calibration reference power source (5) with its contacts (3-1), and the second relay (3) controls the calibration reference power source (5) with its contacts (3-1).
4) switches between the output of the shunt resistor SH (9) and the output of the calibration reference power supply (5) at the contact (4-1), and the amplifier (6)
). (The output value of the calibration reference power supply (5) and the output value of the shunt resistor (9) are recorded on the same recording paper using a recording instrument such as a photocoder. (8) supplies the current to the load θQ. The AC current value flowing to the load from the AC power supply is determined by the shunt resistor (9).Next, the operation shown in Figure 1 will be explained using the timing diagram of Figure 2.5TAH,',I'
When a signal is generated, the oscillator (1) oscillates with a duty of 10m5 and drives the relay KIGJ)'f-. On the other hand, the monomulti (2) drives the relay 2 (4) between 200+ηS and controls the calibration reference power supply (5). The contact (4-1) of 4) is connected to the output side of the calibration reference power supply (5) for 10 ms and input to AM, P (61).When the distance exceeds 200m5 from 5TART, the relay operates as 2 (/1). stops, and the input of AA4P (61) is switched to the output of the shunt resistor (9) by the contact (4-1). To explain this using Fig. 2, relay x < 1 (
3; Operation Fi] Oscillates at On+s intervals, and its output value is temporarily set to 50 mV. 2 (4) to the relay is 200m
The output of the shunt resistor SH (9) is the voltage conversion of the current flowing through the load, and the 'AMP output' shown in Figure 3 shows these series of operating states. . The output of shunt resistor 5H (9) is now 30
Assuming that the shunt resistance generates 50 mV when a current of A flows, the width value of the calibration reference power source (5) recorded on the recording paper of the photocoder (7) is the shunt resistance SH (9).
This corresponds to the amplitude of 11 prefectures when 3OA flows in the current.With this method, the current flowing from the recording paper to the load can be circularized, and the measurement method can be simplified.

The above description of AC current measurement can also be applied to direct current (DC current) measurement. [Effects of the Invention] The present invention is as described above. This eliminates the need for prior calibration work. it) Recording There is no need to worry about variations in earthenware (photocoder, etc.). 1
11) A series of operations are automatically performed by interlocking the S'rAR'r signal with the recording device. 1v) When stored as a record Since the reference power source amplitude value for calibration and the actual load current are recorded on the same recording paper at measurement rt5, reading at a later date is also possible. 0 where you can get the effect of a hat

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are circuit diagrams showing one embodiment of the present invention, and FIG. 2 is an operation timing waveform diagram. 1; First signal generator 2: Second signal generator 3: First switch 4; Second switch 5; Reference power source 6;
Thirst 4P 7: tt1 recording instrument 8; Power source 9; Shunt resistor 10; Current load circuit agent Valve J! It person well
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Claims (1)

[Claims] A first signal generator with a short cycle, a second signal generator with a long cycle that is an integral multiple of the first signal generator, and an AND output of the outputs of the first and second signal generators drive the reference power supply voltage with the amplitude. a first relay switch that generates a short-cycle clock; and a first relay switch that is driven by the second signal generator to generate a long-cycle clock, and outputs the short-cycle clock according to its high/low level. A second relay switch that alternately outputs a voltage drop output caused by a shunt resistor of a current load circuit, and a voltage output proportional to the reference voltage and load current in the short cycle is made the same every time the level of the long cycle clock changes. 1. A current recording and measuring device characterized by comprising a recording instrument that alternately records on paper.