JPH0982211A - Method and circuit for measuring fuse characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure more precise time necessary for fusing after an alternating voltage is impressed. SOLUTION: One and the same alternating current voltage is placed at the same time across a series connection circuit having a fuse F1 and a resistor 11A and across a series connection circuit having a fuse F2 and a resistor 11B. Negative pole half waves of a voltage V proportional to an interterminal voltage of the resistance 11A are removed by a (+) half-wave rectifying circuit 21A, and positive pole half waves of a voltage V proportional to an interterminal voltage of the resistance 11B are removed by a (-) half-wave rectifying circuit 21B. Then polarity of an output voltage of the (-) half-wave rectifying circuit 21B is inverted by an inverting circuit 22, and an output voltage of the (+) half-wave rectifying circuit 21A and an output voltage of the inverting circuit 22 are summated by an addition circuit and thereafter supplied to a peak-hold circuit 24, and an output voltage of the peak-hold circuit 24 is compared with a reference voltage by a comparison circuit 17C. A time length after the alternating current voltage is placed until the fuse F1 or the fuse F2 melts to cause a comparison result of the comparison circuit 17C to be inverted is measured by a time measuring circuit 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse characteristic measuring method and circuit for measuring, as a fuse characteristic, a time until a fuse is blown after an alternating current is supplied.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional fuse characteristic measuring circuit. The fuse module 10 includes a fuse F1 and a fuse F2 as one set. Series connection circuit of fuse F1 and resistor 11A, fuse F2 and resistor 11
In the series connection circuit with B, the voltage from the AC voltage source 12
Simultaneously applied in parallel via relay contacts 14 that are turned on by relay circuit 13. The fuse characteristic measuring circuit is for measuring the time until the fuse F1 or the fuse F2 is blown after the AC voltage is applied, as the fuse characteristic.

The voltage between the terminals of the resistor 11A is determined by the attenuation circuit 1
5A attenuates, full-wave rectifier 16A full-wave rectifies, comparator 17A shapes rectangular pulses,
The pulse / level conversion circuit 18A raises the level to a high level while the pulse is present. Pulse / level conversion circuit 18A
Is a retriggerable monostable multivibrator, which is triggered by the rising edge of the input pulse and outputs a pulse having a width T determined by the time constant. The pulse width T is defined to be retriggered during the pulse period.

In FIG. 4, the voltage waveform between the terminals of the resistor 11A, the attenuation circuit 15A, the full-wave rectification circuit 16A, and the comparison circuit 1 are shown.
7A and the output voltage waveform of the pulse / level conversion circuit 18A are shown. The resistor 11B has the same resistance value as that of the resistor 11A, and has the attenuation circuit 15B and the full-wave rectification circuit 16
B, comparison circuit 17B and pulse / level conversion circuit 18B
Have the same configuration as the attenuation circuit 15A, the full-wave rectification circuit 16A, the comparison circuit 17A, and the pulse / level conversion circuit 18A, respectively.

Pulse / level conversion circuits 18A and 18B
Of the output of the time measurement circuit 20 via the NAND gate 19.
Is supplied to. A start signal is also supplied to the time measuring circuit 20. When the start signal is activated, the relay contact 14 is turned on and the time measurement circuit 20 starts time measurement. If the fuse module 10 is not blown, the output of the NAND gate 19 is low level, and the time measuring circuit 20 continues the measurement. When the fuse F1 or the fuse F2 is blown, the stop signal becomes high level, and the time measuring circuit 20 holds and outputs the time.

[0006]

In the pulse / level conversion circuits 18A and 18B, the rising edge of the output pulse of the comparison circuit 17A fluctuates in the time axis direction due to amplitude fluctuations of the output voltage of the AC voltage source 12, etc. Even if the time constant changes due to a change in temperature, the output of the pulse / level conversion circuit 18A is maintained at a high level so long as the fuse is not blown. Therefore, the measured fuse characteristic value becomes inaccurate.

In view of the above, an object of the present invention is to provide a fuse characteristic measuring method and a circuit capable of more accurately measuring the time until the fuse is blown after an AC voltage is applied. .

[0008]

According to a first aspect of the present invention, there is provided a series connection circuit of a first fuse and a first resistor,
The same AC voltage is simultaneously applied in parallel to the series connection circuit of the second fuse and the second resistor, and after the AC voltage is applied, the first AC voltage is applied.
In a fuse characteristic measuring circuit for measuring a time until a fuse or the second fuse is blown, a first half-wave rectifying circuit for removing a half-wave of one polarity of a voltage proportional to a voltage between terminals of the first resistor, A second half-wave rectifier circuit for removing a half-wave of a voltage proportional to the terminal voltage of the second resistor, the half-wave having a polarity opposite to the one, an output of the first half-wave rectifier circuit, and the second half-wave rectifier circuit An operation circuit that outputs a signal proportional to the difference between the output of the operation circuit, a peak hold circuit to which the output signal of the operation circuit is supplied, a comparison circuit that compares the output voltage of the peak hold circuit with a reference voltage, and the alternating current And a time measuring circuit for measuring a time until the comparison result of the comparison circuit is reversed after the first fuse or the second fuse is blown after the voltage is applied.

According to this fuse characteristic measuring circuit, the first
When the fuse or the second fuse is blown, the output voltage of the first half-wave rectification circuit or the second half-wave rectification circuit becomes 0, and the time and amount of the output hold period of the peak hold circuit increases, and the output of the comparison circuit Changes immediately, the time until the fuse blows after the AC voltage is applied can be measured more accurately than before.

In the second invention, the same AC voltage is simultaneously applied in parallel to the series connection circuit of the first fuse and the first resistance and the series connection circuit of the second fuse and the second resistance, and after the AC voltage is applied. In the fuse characteristic measuring method for measuring the time until the first fuse or the second fuse is blown, a signal obtained by removing a half wave of one polarity of a voltage proportional to the terminal voltage of the first resistor, A signal proportional to the difference between the one of the voltages proportional to the voltage between the terminals of the second resistor and the signal from which the half-wave having the opposite polarity is removed is generated, and the generated signal is applied to a peak hold circuit to generate the peak. The output voltage of the hold circuit is compared with a reference voltage, and the time until the first fuse or the second fuse is blown after the application of the AC voltage and the comparison result of the comparison circuit is reversed is measured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a fuse characteristic measuring circuit according to a first embodiment of the present invention. Fuse module 10,
Resistors 11A, 11B, AC voltage source 12, relay circuit 1
3, the relay contact 14, the attenuation circuits 15A and 15B, and the time measurement circuit 20 are the same as those in FIG. 4, and the description thereof will be omitted.

The output voltage signal V2 of the attenuation circuit 15A is
The negative half-wave is supplied to the (+) half-wave rectifier circuit 21A, and the negative half-wave is removed, resulting in the voltage signal V3A. The voltage signals V1, V2 and V3A are as shown in FIGS. 2 (A) to 2 (C), respectively.
On the other hand, the (-) half-wave rectifier circuit 21B removes the positive half-wave from the output of the attenuation circuit 15B and outputs the voltage signal V3B as shown in FIG. 2 (D). The polarity of the voltage signal V3B is inverted by the inverting circuit 22 to become the voltage signal V3C as shown in FIG.

The voltage signal V3A and the voltage signal V3C are supplied to the adder circuit 23 and become a voltage signal V4 as shown in FIG. 2 (F). The voltage signal V4 is supplied to the peak hold circuit 24 and becomes a voltage signal V5 as shown in FIG. The voltage signal V5 is output from the comparison circuit 17C as shown in FIG.
It is compared with a reference voltage ES as shown in
The output voltage signal V6 of the comparison circuit 17C is at a low level. The voltage signal V6 is supplied to the time measuring circuit 20 as a stop signal.

The time measuring circuit 20 has a flip-flop which is set when the start signal becomes active and is reset by the rising of the voltage signal V6.
While this flip-flop is set, the time is measured by counting the clock with the counter. In the above configuration, when the start signal is activated, the relay contact 14 is turned on and the time measurement circuit 20 starts time measurement. Immediately after the start, the stop signal is temporarily turned on, which is ignored in the time measuring circuit 20. If the fuse module 10 is not blown, the voltage signal V6 is at a low level and the time measuring circuit 20 continues the measurement. Fuse F1 or fuse F2
2B, the voltage signal V5 becomes as shown in FIG. 2 (H), the voltage signal V6 temporarily becomes high level as shown in FIG. 2 (I), and the time measuring circuit 20 shows the time until the rising time of this pulse. Hold and output.

According to the first embodiment, as is clear from FIG. 2H, immediately after the fuse F1 or the fuse F2 is blown, V5 <ES is temporarily established, so that the fuse characteristic can be measured more accurately. be able to. Also, FIG.
Although the time constants of the pulse / level conversion circuits 18A and 18B of FIG. 1 change depending on the ambient temperature, the reference voltage ES of the comparison circuit 17C in FIG. 1 is hardly affected by the ambient temperature, so that the error in the measurement time due to the ambient temperature is reduced. it can.

[Second Embodiment] In FIG. 1, instead of inverting the voltage signal V3B in the inverting circuit 22, the voltage signal V3 is used.
The configuration may be such that A is inverted and the output voltage signal of the adder circuit 23 is inverted. Such a configuration is shown in FIG. 3 as a second embodiment. In FIG. 3, the resistor 111A
1 corresponds to the resistor 11A of FIG. 1, and the series connection of the resistor 111B and the resistor 112B corresponds to the resistor 11B of FIG. With such series connection, the resistors 111A and 111B correspond to the attenuation circuits 15A and 15B of FIG. 1, respectively, and the configuration is simplified.

A voltage follower 26A, which is a buffer amplifier having an amplification factor of 1, is connected to the connection point between the resistors 11A and 112A, and similarly, the resistors 11B and 1A are connected.
A voltage follower 26B is connected to the connection point with 12B. As shown in FIG. 3, the (+) half-wave rectification circuit 21
Each of the A and (-) half-wave rectifier circuits 21B is composed of a diode and a resistor, the inverting circuit 22 is composed of an operational amplifier and a resistor, and the adding / inverting circuit 23X is composed of an operational amplifier and a resistor. The hold circuit 24 is composed of an operational amplifier, a diode, a capacitor and a resistor.

The relay contacts 14A and 14B are operated in conjunction with each other by the relay circuit 13 that holds the start pulse, and correspond to the relay contact 14 of FIG. The operation of the second embodiment can be easily understood from the operation of the above-described first embodiment, and thus the description thereof will be omitted. In addition, the present invention includes various modifications. For example, in FIG. 3, the addition / inversion circuit 23X may be replaced with a subtraction circuit without using the inversion circuit 22.

[Brief description of drawings]

FIG. 1 is a block diagram showing a fuse characteristic measuring circuit according to a first embodiment of the present invention.

FIG. 2 is a voltage waveform diagram showing an operation of the circuit of FIG.

FIG. 3 is a fuse characteristic measurement circuit diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional fuse characteristic measuring circuit.

[Explanation of symbols]

10 Fuse module F1, F2 Fuse 11A, 11B, 111A, 112A, 111B, 11
2B resistor 12 AC voltage source 13 Relay circuit 14, 14A, 14B Relay contact 15A, 15B Attenuation circuit 20 Time measurement circuit 21A (+) Half-wave rectification circuit 21B (-) Half-wave rectification circuit 22 Inversion circuit 23 Addition circuit 23X Addition・ Inversion circuit 24 Peak hold circuit

Claims (2)

[Claims] 1. The same AC voltage is simultaneously applied in parallel to a series connection circuit of a first fuse and a first resistance and a series connection circuit of a second fuse and a second resistance, and after applying the AC voltage,
In a fuse characteristic measuring circuit for measuring a time until the first fuse or the second fuse is blown, a first half wave for removing a half wave of one polarity of a voltage proportional to a voltage between terminals of the first resistor. A rectifying circuit, a second half-wave rectifying circuit that removes a half-wave of a voltage proportional to the voltage across the second resistor, the half-wave having a polarity opposite to the one, and an output of the first half-wave rectifying circuit and the second half-wave. An arithmetic circuit that outputs a signal proportional to the difference from the output of the wave rectifier circuit, a peak hold circuit to which the output signal of the arithmetic circuit is supplied, and a comparison circuit that compares the output voltage of the peak hold circuit with a reference voltage A fuse characteristic measurement, comprising: a time measuring circuit for measuring a time until the comparison result of the comparison circuit is reversed after the first fuse or the second fuse is blown after the application of the AC voltage. circuit. 2. The same AC voltage is simultaneously applied in parallel to a series connection circuit of a first fuse and a first resistance and a series connection circuit of a second fuse and a second resistance, and after the AC voltage is applied, the first AC voltage is applied. In a fuse characteristic measuring method for measuring a time until one fuse or the second fuse is blown, a signal obtained by removing a half wave of one polarity of a voltage proportional to a voltage between terminals of the first resistor and the second A signal proportional to the difference between the one of the voltage proportional to the voltage between the terminals of the resistor and the signal from which the half wave having the opposite polarity is removed is generated, and the generated signal is applied to the peak hold circuit. A fuse characterized by comparing an output voltage with a reference voltage and measuring a time until the comparison result of the comparison circuit is reversed after the first fuse or the second fuse is blown after the application of the AC voltage. Characteristic measurement method.