JPH04208873A - Apparatus for detecting life of capacitor - Google Patents

Abstract

PURPOSE:To prevent effectively the trouble occurrence by a capacity down, etc., by switching a capacitor over to a backup capacitor by a change-over switch when the capacity value of the capacitor becomes a threshold value and less. CONSTITUTION:The voltage according to the stored changes corresponding to each capacity value of capacitors 3, 5 is in order applied to a capacitor check circuit 12 through a switch SW5 and compared with a reference value by a comparator 13, an alarm generates from an alarm generating circuit 14 when the capacity of the capacitor 3 or 5 becomes a threshold value and less, and the life of the condenser 3 or 5 is informed. Simultaneously, the capacitor 3 or 5 is switched to the corresponding backup capacitor 10 or 11 by switches SW1 and SW2, SW3 and SW4 of the capacitor whose life has expired. The trouble occurrence of a capacity down, etc., is efficiently prevented and the life of the capacitor can be inspected without the reduction of reliability for the apparatus, using the capacitor by this.

Description

[Detailed Description of the Invention] [Objective of the Invention] [Industrial Field of Application] The present invention is intended for use in electrical circuits, etc. of radiometer systems that require high reliability, for example in nuclear power plants, etc. This invention relates to a lifespan detection device for detecting the lifespan of a capacitor.

[Conventional technology]

Electrolytic capacitors used in power supplies, electronic circuits, etc. generally have a shorter lifespan than other electronic components (transistors, resistors, ICs, etc.), and are a major factor in determining the lifespan of devices that use electrolytic capacitors. was. The cause of deterioration of electrolytic capacitors is a decrease in capacitance caused by electrolyte gradually permeating through the sealed portion over time. This diffusion of the electrolyte progresses in proportion to the ambient temperature and the heat generation temperature of the capacitor itself.

Conventionally, the lifespan of a capacitor was predicted at the time of design, and when a capacitor built into an electronic circuit approached its expected lifespan, the capacitor was replaced to prevent deterioration of the capacitor.

By the way, electrolytic capacitors are also used in equipment that requires extremely high reliability, such as radiation measurement systems.
In devices that require such high reliability, if an electrolytic capacitor reaches the end of its life and experiences "capacity leakage," it is likely to have a major impact on the entire device. For example, if noise is included in the dFI constant data due to "capacitance loss" of an electrolytic capacitor, a false alarm may be output due to this noise. Therefore, in equipment that requires high reliability, the lifespan of the electrolytic capacitors used can be accurately predicted.
il L, it is necessary to ensure that the electrolytic capacitor is replaced before it reaches the end of its life.

However, due to fluctuations in the ambient temperature in which electrolytic capacitors are used, fluctuations in the load on the capacitor itself, etc., the lifespan of electrolytic capacitors may be significantly shorter than expected at the time of design.

[Problem to be solved by the invention]

Therefore, in the past, it was not possible to accurately predict the lifespan of a capacitor, and there was a risk that troubles would occur due to the capacitor's ``capacitance leakage'', which was a factor that reduced the reliability of devices using capacitors. It had become.

The present invention was made in view of the above-mentioned circumstances, and it is possible to detect the lifespan of capacitors used in electric circuits, effectively prevent troubles caused by "capacitance leakage", etc., and improve the use of capacitors. The purpose of the present invention is to provide a capacitor life detection device that can improve the reliability of the device.

[Structure of the Invention] [Means for Solving the Problem] In order to achieve the above object, a capacitor life detection device according to the first invention detects the life of a capacitor incorporated in a predetermined electric circuit. A capacitance value detection means is connected to the capacitor and detects a voltage according to the amount of charge accumulated in the capacitor and converts it into the capacitance value of the capacitor. a backup capacitor incorporated in the electric circuit, a changeover switch for switching between the capacitor to be inspected and its backup capacitor, and a capacitance value detected by the capacitance value detection means that is a threshold value. When the value is below the value, the selector switch is switched to the backup capacitor, and
The capacitor life detection device according to the second invention is equipped with an alarm means for notifying that the capacitor to be inspected has reached the end of its lifespan. a temperature sensor installed in the capacitor, and a damage amount calculation means for monitoring temperature data output from the temperature sensor and calculating damage to the capacitor from the amount of temperature change accumulated over time; The apparatus further includes an alarm means for notifying that the capacitor has reached the end of its life when the amount of damage calculated by the means exceeds the allowable value of the capacitor.

[Effect]

According to the first invention, when inspecting the life of a capacitor built into an electric circuit, a backup capacitor is built into the electric circuit in place of the capacitor, and the capacitance value detection means is connected to the capacitor to measure the capacitance value. Detected.

Then, when this detected capacitance value is below the threshold value,
In other words, an alarm is output when the life is nearing the end. Therefore, the life of the capacitor can be detected at any time or at a predetermined period without causing missing measurements in the device in which the capacitor is used.

According to the second invention, a temperature change that affects the life of a capacitor incorporated in an electric circuit is detected by a temperature sensor, and the amount of damage to the capacitor is calculated from the detected amount of temperature change. An alarm is output when the value exceeds the allowable value of the capacitor. Therefore, it is accurately notified that the capacitor is nearing the end of its life before "capacitance loss" occurs in the capacitor, and the capacitor can be replaced before the end of its life.

〔Example〕

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

FIG. 1 is a diagram showing a first embodiment of the present invention.

This embodiment is an example of a life detection device for a smoothing electrolytic capacitor (hereinafter referred to as a "smoothing capacitor") provided in a DC power supply circuit used in a power supply section of a radiation measurement system.

In the DC power supply circuit, an AC voltage generated by an AC power supply 1 is full-wave rectified by a full-wave rectifier circuit 2 consisting of a diode bridge circuit. A smoothing capacitor 3 is provided between both output terminals of the aftermath rectifier circuit 2. Similarly, two terminals of the three-terminal regulator 4 are connected between both terminals, and the remaining terminals of the three-terminal regulator 4 and the (-
) side terminal is provided with a smoothing capacitor 5.

The (+) electrode side of the smoothing capacitor 3 is connected to the (+) side terminal of the full-wave rectifier circuit 2 via a changeover switch SW1, and a resistor Ra and a changeover switch SW2 that bypass this changeover switch SWI. connected via. Further, the (+) side electrode of the smoothing capacitor 5 is connected to the three-terminal regulator 4 via a changeover switch SW3. In addition, this changeover switch SW2
Bypassing the resistor Rb and selector switch S
It is connected to the three-terminal regulator 4 via W4.

In the DC power supply circuit configured in this manner, the life detection device of this embodiment has a backup capacitor 1.0.11 provided in parallel with the smoothing capacitor 3.5. One electrode of the backup capacitor 10 is connected to the (-) of the full-wave rectifier circuit 2 similarly to the smoothing capacitor 3.
is connected to the side output terminal, and the other electrode is connected to the selector switch S.
It is connected to the (-) side output terminal of the full-wave rectifier circuit 2 via WI, and further connected to the resistor Ra via a changeover switch SW2. The other backup capacitor 11 has one electrode connected to the (-) side output terminal of the full-wave rectifier circuit 2 together with the smoothing capacitor 5, and the other electrode connected to the output terminal of the 3@ child regulator 4 via the changeover switch SW3. terminal, and further connected to the resistor Rb via a changeover switch SW4.

A capacitor check circuit 12 for detecting the capacitance values of the smoothing capacitors 3 and 5 is connected to the (+) side of the smoothing capacitors 3 and 5 via a selection switch SW5. This capacitor check circuit 12 includes a selection switch SW5.
A voltage corresponding to the capacitance value of the smoothing capacitor 3 or 5 connected through the capacitor is generated. The output voltage of this capacitor check circuit 12 is applied to one input terminal of a comparator 13. The other input terminal of the comparator 13 is set to a voltage level corresponding to the permissible capacitance value of the smoothing capacitors 3 and 5, and when the output voltage of the capacitor check circuit 12 falls below the set voltage, an alarm generation circuit]
An active signal is output to 4.

The capacitor check circuit 12, as shown in FIG.
The impedance 71PI constant circuit 15 and the impedance conversion circuit 16 can be combined. Impedance 4pj constant circuit 15 and smoothing capacitor 3.
5 (+) side electrode voltage is input, and a voltage corresponding to the impedance is input to the impedance conversion circuit 16. By adjusting the resistances R, , R2°R9, and capacitance CR of the impedance conversion circuit 16 configured as shown in the figure,
Cx can be set to match the capacitance value of the smoothing capacitors 3 and 5 depending on the input impedance, and a voltage corresponding to the detected capacitance value Cx is generated.

Next, as an example of the operation of this embodiment configured as described above, the life detection operation of the smoothing capacitor 3 will be explained.

Normally, the changeover switch SW1 is connected to the smoothing capacitor 3 side terminal, and is switched to the backup capacitor 10 side terminal when life is detected.

The changeover switch SW2 is connected to the same capacitor side as the changeover switch SWI, and is operated so as to be connected to the same capacitor side whenever the changeover switch SWI is switched. This prevents surge noise that occurs when the switch SWI is switched.

When detecting the life of the smoothing capacitor 3, SWI and 2 are switched to the backup capacitor 10 side by external operation, and the selection switch SW5 is switched to the smoothing capacitor 3 side.
can be switched to the side. During the life detection operation, smoothing processing is performed by the backup capacitor ]0. On the other hand, a voltage corresponding to the amount of charge accumulated in the smoothing capacitor 3 to be inspected is input to the capacitor check circuit 12. The capacitor check circuit 12 includes a smoothing capacitor 3
A voltage indicating the current capacitance value of is output to the comparator 13. The comparator 13 outputs a signal to the alarm output circuit 14 to output an alarm when the voltage indicating the current capacitance value of the smoothing capacitor 3 is below a set value, that is, when it is below the allowable capacitance value of the smoothing capacitor 3. .

In addition, if an alarm is output, selector switch S
Keeping the state of WI, 2 as it is, smoothing capacitor 3
exchange. Also, if the alarm is not output,
Return the selector switch SWI, 2 to the smooth conduit laser 3 side to return to the normal state.

Furthermore, lifespan detection is executed in the same manner for the smoothing capacitor 5.

In this way, in this embodiment, each smoothing capacitor 3.5 to be inspected is connected to a backup capacitor 10.11.
The capacitor check circuit 1 performs smoothing processing using the backup capacitor 10.
2 is detected, and an alarm is output when this capacitance value (%) is less than the allowable value. The service life of the smoothing capacitor 3.5 can be detected in advance, and "capacitance leakage" can be prevented.Therefore, the reliability of the device can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a block diagram of this embodiment. Code 20 in the diagram
indicates an electrolytic capacitor to be tested for life installed in the device. In this embodiment, a temperature sensor 21 is installed near this electrolytic capacitor 20, and the sensor output is A.
The signal is input to the arithmetic processing unit 23 via the /D converter 22.

The database 24 stores estimated lifespans of capacitors used that have been determined in advance through experiments and the like, as well as alarm settings corresponding to these estimated lives. The arithmetic processing unit 23 is
The output of the A/D converter 22 is taken in at a predetermined period, and damage to the capacitor 20 is calculated from the temperature data by a calculation described later. Then, the amount of damage calculated at each predetermined period is added up, and when the accumulated damage amount (added value) exceeds the alarm setting value, an alarm output command signal is output. The alarm output circuit 25 generates an alarm upon receiving the alarm output command signal.

Here, damage calculation in the calculation processing section 23 will be explained.

Assuming that the life of the capacitor 20 is determined by the ambient temperature, the estimated life LT is LT,, L oX 2tTo-T) "I O, where T is the ambient temperature and To is the maximum rated temperature. Lo is the estimated lifespan at the maximum rated temperature (To), and is a value that is determined in advance and stored in the database 24.

In the arithmetic processing unit 23, the life L at the set π1 temperature (Ts)
s and the life LT at the actually measured ambient temperature (T), Ls/L7, is calculated as the amount of damage at the ambient temperature at a constant time of 'l-1.

According to this embodiment, the ambient temperature of the electrolytic capacitor 20 is detected at a predetermined period by the temperature sensor 2,
Based on the detected ambient temperature data, the arithmetic processing unit 23 calculates the damage that the electrolytic capacitor 20 receives at that temperature.

The damage to the electrolytic capacitor 20 is calculated every time the ambient temperature is detected, and when the total amount of damage calculated exceeds the alarm setting value, an alarm output command signal is output and the alarm generation circuit 25 issues an alarm. is generated.

Therefore, the capacitor can be reliably replaced before the electrolytic capacitor 20 reaches the end of its life, preventing troubles such as "capacity leakage" from occurring, and improving the reliability of the device.

In addition, in each of the above embodiments, electrolytic capacitors were used as an example, but electrolytic capacitors have a larger fluctuation range in capacitance value than other capacitors, so if "capacitance leakage" occurs, there is a high probability that a problem will occur. Because of the high cost, it is particularly effective to apply to such capacitors. It goes without saying that other capacitors can also be used.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to detect the lifespan of a capacitor used in an electric circuit, replace the capacitor at an appropriate time, and prevent "capacitance loss" etc. Accordingly, it is possible to provide a capacitor life detection device that can effectively prevent troubles caused by this and improve the reliability of devices using capacitors.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a first embodiment of the present invention, Fig. 2 is a block diagram of a capacitor check circuit used in the same embodiment, and Fig. 3 is a block diagram of a capacitor check circuit used in the same embodiment.
The figure is a configuration diagram of the second embodiment. 3.5...Smoothing electrolytic capacitor, 4...3-terminal regulator, 10.11...Backup capacitor, 12...Capacitor check circuit, 13...Comparator, 14.25...Alarm generation circuit , 21・Temperature sensor, 23... Arithmetic processing unit. Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) When inspecting the life of a capacitor incorporated in a predetermined electric circuit, a capacitance value detection means that is connected to the capacitor and detects a voltage corresponding to the amount of accumulated charge in the capacitor and converts it into a capacitance value of the capacitor; a backup capacitor that is placed in parallel with the capacitor and is incorporated into the electrical circuit in place of the capacitor during a lifespan test of the capacitor; and a changeover switch for switching between the capacitor to be tested and the backup capacitor. and, when the capacitance value of the capacitor detected by the capacitance value detection means is less than a threshold value, an alarm is generated to switch the changeover switch to a backup capacitor and to notify that the capacitor to be inspected has reached the end of its service life. A capacitor life detection device characterized by comprising: a means for detecting the life of a capacitor; (2) Monitoring a temperature sensor installed near a capacitor incorporated in a predetermined electric circuit and temperature data output from the temperature sensor,
damage amount calculation means for calculating the damage to the capacitor from the amount of temperature change accumulated over time; and when the damage amount calculated by the damage amount calculation means exceeds the allowable value of the capacitor, the capacitor A capacitor life detection device characterized by comprising: an alarm means for notifying that the life has come to an end;