JPS63292547A - Monitoring device for protection element - Google Patents

Abstract

PURPOSE:To make replacement of protection element by measuring an calculating the resistance value of the protection element of a power conversion element by a resistance value measuring/calculating means, and by judging deterioration of protection element from the measured and calculated resistance value by a comparator means and a judging means. CONSTITUTION:Shunted current of DC power is sensed by an ammeter 27, whilevoltage drop at a fuse 2 is sensed by a voltometer 28, and these signals from sensing are converted into digital signals by A/D converters 29, 30. The output signals are put into a resistance value calculating circuit 31, and from these input signals the resistance value is computed, followed by correction into a resistance value corresponding to a specified temp. by a temp. correction circuit 32. This corrected resistance value is compared with the initial resistance value stored in a memory circuit 33 by a comparator circuit 34, and the rate of change of the resistance value is computed. Thus the corrected resistance value on the basis of the sensed resistance value is compared with the reference resistance value, and when the corrected value exceeds the reference value, the fuse 2 is judged to have been deteriorated. This provides optimum judgement of the replacement timing for a protection element such as a fuse 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a protection element monitoring system for protecting a power conversion element used in a power conversion device or the like.

(Prior art) High-speed current-limiting fuses (hereinafter referred to as fuses) are generally used as protection elements for power conversion elements used in power conversion equipment.
is used.

This fuse was generally said to be maintenance-free, and was thought to have no lifespan.

However, recently, accidents have occurred one after another in which the fuse element deteriorates due to thermal fatigue and breaks. However, although conventional fuse monitoring has provided clues for elucidating the deterioration mechanism of the fuse element and estimating its lifespan, it cannot be said to be sufficient monitoring. The lifespan is estimated using an experimental formula, and the estimation accuracy is improved by accumulating data over a long period of time by testing numerous samples under various energizing load patterns. Further, the deterioration of the fuse is determined by checking the change in resistance value and determining the progress of deterioration. At this time, the lead wires of a resistance measuring device are connected to both ends of the fuse provided in the power converter, and the resistance value of each fuse is measured one by one.

(Problem to be Solved by the Invention) In the conventional fuse monitoring described above, since there are several dozen or more power converters in one plant, the number of fuse resistance values to be measured is determined based on the fuse rating and similar load pattern. Even if they are divided into groups, there will be a considerable number of them and it will take time and effort.

Also, if you set the fuse replacement period for a certain period of time, it may be a waste of money to replace the fuse even though it has not deteriorated yet, or the fuse may deteriorate.
When a fuse breaks, the power converter itself has to be stopped, which adversely affects the entire plant.

Therefore, an object of the present invention is to provide a protective element monitoring device that can optimally determine when to replace a protective element such as a fuse and reduce labor.

[Structure of the invention]

Means and operation for solving problem C) Therefore, in order to achieve the above object, the present invention provides ``resistance value measurement and calculation means for measuring and calculating the resistance value of a protection element that protects a power conversion element; Comparing means for comparing the output signal from the resistance value measuring and calculating means with a preset setting signal; and determining means for monitoring the deterioration state of the protective element based on the output signal from the comparing means and determining whether to replace the protective element. a protection element monitoring device comprising a protection element monitoring device, a resistance value measurement calculation means for measuring and calculating the resistance value of a protection element that protects an RZ power conversion element, and a storage means for storing an output signal from the resistance value measurement calculation means;
Comparison and monitoring means for comparing the output signal from the resistance value measurement and calculation means with the output signal from the storage means and monitoring changes in the resistance value of the protection element, and converting the protection element using the output signal from the comparison and monitoring means. A protective element A and a child monitoring device J are provided.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

In addition, in this example, a thyristor, a
A fuse monitoring device in a power conversion device to which a high-speed current-limiting fuse (hereinafter referred to as fuse) is applied as a protection element will be described. In this power converter, both ends of the fuse are connected to external terminals.

As shown in FIG. 1, a plurality of power converters 1 are selected based on fuse ratings and similar load patterns from among 10 or more power converters per plant, and the power converters 1 installed in the power converters 1 are Both ends of the fuse 2 are connected to an external terminal 3, and connected to a fuse monitoring device 12 via an external cable 11, thereby establishing a connection between devices.

Next, as shown in FIG. 2, the fuse monitoring device 12
The switch 20 turns on and off the connection to the fuse 2, and the switch 21 selects the fuse 2 whose resistance value is to be measured. In addition, an AC power source (not shown) as a power source for measurement is turned on and off by a switch 22, and the input AC power is voltage-adjusted by a voltage regulator 23 and converted to DC power by a regulator 24. and smoothed by the DC reactor 25. Further, an ammeter 27 detects the current of the DC power shunted by a shunt 26 provided between the rectifier 24 and the DC reactor 25, and a voltmeter 28 provided on the output side of the DC reactor 25 detects the current of the fuse 2. The detection signals detected by the ammeter 27 and the voltmeter 28 are converted into digital signals by the A/D converters 29 and 30. Each output signal converted by the A/D converter 29, 30 is input to a resistance value calculation circuit 31, and the resistance value calculation circuit 3I calculates a resistance value based on these input signals. Since this calculated resistance value is affected by the ambient temperature, it is corrected by the temperature correction circuit 32 to a resistance value corresponding to a predetermined temperature. This corrected resistance value is compared with the initial resistance value stored in the storage circuit 33 by the comparison circuit 34,
The rate of change in resistance value is calculated. This calculation result is outputted by an output means such as a printer or CRT. The items to be typed out are the equipment name of the fuse 2, the initial resistance value, the resistance value change ratio, and "Measurement I", which are typed out for each number of measurements so that the change in resistance value can be seen. or,
The data can also be stored by providing a data storage circuit 35. The resistance value should be measured once a year for 5 years or more.
Once the resistance has passed, replace it about twice a year, and if the resistance value changes by about 5%, increase the number of times, such as once a month, and when it reaches 10% or more, it's time to replace the fuse. exchange.

Next, another embodiment of the present invention will be described using FIG.

As shown in FIG. 3, the fuse monitoring device of this embodiment is as follows:
A switch 50 that turns on and off the connection to the fuse 2, a changeover switch 51 that selects the fuse 2 whose resistance value is to be measured, and a switch 51 that turns on and off the connection to the fuse 2, and a switch 51 that turns on and off the power supply from an AC power source (not shown) as a measurement power source. A switch 52 that turns off the power, a voltage regulator 53 that adjusts the voltage of the AC power that has been discharged through the switch 52, and a rectifier 54 that converts the output AC power from the voltage regulator 53 into DC power. This rectifier 54
A DC reactor 55 that smoothes the DC power from the DC reactor 55, a rectifier 54, a shunt 56 provided between the rectifier 54 and the DC reactor 55, and a current that detects the shunted DC current from the shunt 56. 57, a voltmeter 58 that detects the voltage drop of fuse 2, and A that converts each output signal from ammeter 57 and voltmeter 58 into a digital signal.
/D converter 59.60 and this A/D converter 5
9. A resistance value calculation circuit 61 that calculates a resistance value based on the output signal from 60, and a temperature correction circuit 62 that corrects the resistance value from this resistance value calculation circuit 61 to a resistance value corresponding to a predetermined temperature in consideration of the ambient temperature. and an abnormality determination circuit 63 that compares the corrected resistance value from the temperature correction circuit 62 with a reference resistance value at a preset predetermined temperature and determines that the resistance value from the temperature correction circuit 62 is abnormal. It consists of

In the fuse monitoring device configured in this way, the reference resistance value is compared with the corrected resistance value corrected based on the detected resistance value, and if the corrected resistance value exceeds the reference resistance value, it is determined that the fuse 2 has deteriorated. The result is output to an output means such as a printer or CI<T.

In addition, although the fuse monitoring devices of the above two embodiments were operated by power supply from an AC power source, the present invention also allows the device itself to be a portable type by replacing the DC power source with a battery and operating the fuse monitoring device. Needless to say, it is applicable.

[Effects of the Invention] As described above, according to the present invention, the resistance value measurement and calculation means can easily measure and calculate the resistance value of the protection element of the power conversion element, and the comparison means and the determination means can easily measure and calculate the resistance value of the protection element of the power conversion element. Since deterioration of the protection element can be determined based on the resistance value determined, appropriate replacement of the protection element becomes possible.

Therefore, it is possible to prevent an adverse effect on the entire plant due to disconnection of the protection element, and to use the protection element effectively in consideration of durability.

[Brief explanation of drawings]

FIG. 1 is a connection diagram between a fuse monitoring device and a power converter according to the present invention, and FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.
FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention. 2...Fuse 12...Fuse monitoring device 31, 61...Resistance value calculation circuit 32, 62...Temperature correction circuit 33...Memory circuit 34...Comparison circuit 63...Abnormality judgment circuit substitute People Patent Attorney Nori Chika Ken Yudo Daishimaru Ken

Claims (1)

[Scope of Claims] 1. A resistance value measurement calculation means for measuring and calculating the resistance value of a protection element that protects a power conversion element, and comparing an output signal from this resistance value measurement calculation means with a preset setting signal. 1. A monitoring device for a protection element, comprising: comparison means for monitoring the deterioration state of the protection element based on an output signal from the comparison means, and judgment means for determining whether to replace the protection element. 2. A resistance value measurement and calculation means for measuring and calculating the resistance value of a protection element that protects a power conversion element, a storage means for storing an output signal from this resistance measurement and calculation means, and a detection unit that measures the resistance value by the resistance value measurement means. Comparison and monitoring means for comparing the signal and the output signal from the storage means to monitor changes in the resistance value of the protection element; and determination means for determining conversion of the protection element based on the output signal from the comparison and monitoring means. A monitoring device for a protective element, characterized by comprising: