JP5331225B1 - Surge protection device life diagnosis device - Google Patents

Abstract

An object of the present invention is to provide a low-cost device for diagnosing the life of a surge protection device capable of accurately judging the life considering the impulse life characteristics of the surge protection device.
A device for diagnosing the life of a surge protection device is configured to hold an input unit 11 to which a signal from a current sensor for detecting a surge current flowing in the surge protection device is input, and a peak value of an analog signal from the input unit 11. Receiving a signal from the first to n-th surge detection units U1 to Un having a peak hold unit 12 and an attenuation unit 13 that exponentially attenuates the analog signal held by the peak hold unit 12, A processing device 1 that performs life diagnosis of the protective device and a display device 2 that displays the diagnosis result are provided.
[Selection] Figure 3

Description

  The present invention relates to a life diagnosis apparatus for a surge protection device, and more particularly to a life diagnosis apparatus for a surge protection device that diagnoses the life of a surge protection device using zinc oxide or the like based on a peak value of a surge current.

  Conventionally, various methods have been developed for the life diagnosis of a surge protective device (SPD: Surge Protective Device), and Patent Document 1 (Japanese Patent No. 4756904) includes about five kinds of methods, and the problems thereof. The points are summarized. As an improvement measure, a device for diagnosing the life of a surge protection device by recording the surge waveform every time a certain amount of voltage proportional to the surge current is recorded and accurately integrating the area of the surge waveform is described. ing.

  In the device for diagnosing the life of a surge protection device disclosed in Patent Document 1, the area of the surge waveform is measured and integrated, and used for determining the life of the surge protection device.

  However, the apparatus for diagnosing the life of the surge protection device has a problem that the life of the surge protection device cannot be accurately determined because the surge intensity is not properly taken into account.

Japanese Patent No. 4756904

  Accordingly, an object of the present invention is to provide a low-cost life diagnosis apparatus for a surge protection device that can perform accurate life determination in consideration of the impulse life characteristics of the surge protection device.

ただし、Ｉ_IN ： 上記サージ電流のピーク値を表すデジタル値
Ｉ_０ ： 基準電流値
α ： 上記サージ防護デバイスによって決まる定数
により演算する。 In order to solve the above problem, a life diagnosis apparatus for a surge protection device according to the present invention provides:
A current sensor for detecting a surge current flowing in the surge protection device;
An A / D converter for A / D converting the surge current detected by the current sensor;
Based on the peak value of the surge current A / D converted by the A / D converter, a calculation unit that calculates a value corresponding to the amount of damage that the surge protection device has received by the surge current;
An accumulating unit for accumulating a value corresponding to the amount of damage received by the surge current by the surge protection device calculated by the calculating unit;
An integrated value determination unit that determines whether the integrated value integrated by the integration unit is greater than or equal to a preset threshold value;
The calculation unit has a value Y corresponding to the amount of damage that the surge protection device has received by the surge current,

However, I _IN : Digital value representing the peak value of the surge current I ₀ : Reference current value α: Calculated by a constant determined by the surge protection device.

  According to the above configuration, the constant α determined by the surge protection device is determined based on the impulse life characteristic example 1 of the surge protection device shown in FIG. 1 (relationship between the number of service life of the surge protection device and the impulse current value). By calculating the value Y corresponding to the amount of damage that the surge protection device has received by the surge current using the above equation, the cumulative amount of damage given to the surge protection device can be obtained accurately. Therefore, accurate life determination considering the impulse life characteristics of the surge protection device can be performed at low cost.

In the surge protection device life diagnosis apparatus of one embodiment,
A peak hold unit for holding a peak value of the surge current detected by the current sensor;
The A / D converter performs A / D conversion on an analog signal representing a peak value of the surge current held by the peak hold unit.

  According to the above embodiment, the analog signal representing the peak value of the surge current held by the peak hold unit is A / D converted by the A / D converter, thereby slowing down the A / D conversion and calculation processing operations. Therefore, it is not necessary to use an expensive A / D converter for high-speed sampling or a DSP (Digital Signal Processor) capable of high-speed processing, and the cost can be reduced.

In the surge protection device life diagnosis apparatus of one embodiment,
An attenuation unit is provided that exponentially attenuates an analog signal representing the peak value of the surge current output from the peak hold unit.

  According to the above-described embodiment, an analog signal representing the peak value of the surge current output from the peak hold unit is exponentially attenuated by the attenuation unit, so that even a processing device having a relatively slow operation has a slow sampling period. A sufficient time for data processing can be secured in the meantime.

In the surge protection device life diagnosis apparatus of one embodiment,
When the integrated value determining unit determines that the integrated value integrated by the integrating unit is equal to or greater than the threshold value, a notification unit is provided to notify that the surge protection device has reached the end of its life.

  According to the embodiment, when the integrated value determination unit determines that the integrated value integrated by the integration unit is equal to or greater than the threshold value, the notification unit notifies the surge protection device that the life has reached the end, thereby providing a surge protection device. Maintenance such as replacement can be performed quickly before the breakage.

ただし、 Ｉ_IN ： 上記サージ電流のピーク値を表すデジタル値
Ｉ_０ ： 基準電流値
α ： 上記サージ防護デバイスによって決まる定数
Ｔ_IN ： 上記サージ電流の継続時間
Ｔ_０ ： 基準継続時間
γ ： 上記サージ防護デバイスによって決まる定数
により演算する。 In the surge protection device life diagnosis apparatus of one embodiment,
A duration measuring unit for measuring the duration of the surge current detected by the current sensor;
The arithmetic unit, based on the duration measured by the duration measurement unit, a value Y corresponding to the amount of damage that the surge protection device has received by the surge current,

However, I _IN : Digital value indicating the peak value of the surge current
I ₀ : Reference current value
α: Constant determined by the above surge protection device
T _IN : Duration of the above surge current
T ₀ : Reference duration
γ: Calculated by a constant determined by the surge protection device.

  According to the above-described embodiment, impulse life characteristic example 1 of the surge protection device shown in FIG. 1 (relationship between the number of times the surge protection device is used and the impulse current value) and impulse life characteristic example 2 of the surge protection device shown in FIG. Based on (Relationship between impulse current and surge wave tail length (impulse length)), constants α and γ determined by the surge protection device are determined, and it corresponds to the amount of damage that the surge protection device received by the surge current by the calculation unit. When the value Y is calculated, the accumulated amount of damage given to the surge protection device can be obtained more accurately by performing correction based on the duration of the surge current using the above equation.

In the surge protection device life diagnosis apparatus of one embodiment,
The duration measuring unit is
A level comparator that compares the level of the surge current detected by the current sensor with a preset level determination value;
And a timer for measuring the duration time during which the level of the surge current has continued to exceed the level determination value by the level comparator.

  According to the above embodiment, the duration time during which the level of the surge current exceeds the level judgment value is measured by the timer by the level comparator, so the duration time of the surge current can be easily measured with a simple configuration. it can.

In the surge protection device life diagnosis apparatus of one embodiment,
The current sensor is a current transformer in which a gap is provided in a part of a core that forms a magnetic path.

  According to the above embodiment, by detecting a surge current flowing in the surge protection device by a current transformer in which a gap is provided in a part of the core forming the magnetic path, a lightning surge can be detected with a low-cost current transformer. Measurement can be performed without saturating a large current.

  As is clear from the above, according to the present invention, it is possible to realize a low-cost device for diagnosing the life of a surge protection device that can accurately determine the life considering the impulse life characteristics of the surge protection device.

FIG. 1 is a diagram showing an impulse life characteristic example 1 of a surge protection device. FIG. 2 is a diagram showing an impulse life characteristic example 2 of the surge protection device. FIG. 3 is a block diagram showing the overall configuration of the surge protection device life diagnosis apparatus according to the first embodiment of the present invention. FIG. 4 is a circuit diagram of an input section of the surge protection device life diagnosis apparatus. FIG. 5 is a diagram showing the configuration of the control unit of the surge diagnostic device life diagnosis apparatus and its surroundings. FIG. 6 is a flowchart for explaining the operation of the control device of the life diagnosis device for the surge protection device. FIG. 7 is a block diagram showing the overall configuration of the surge protection device life diagnosis apparatus according to the second embodiment of the present invention. FIG. 8 is a diagram showing a configuration of a control unit of the life diagnosis apparatus for the surge protection device and its surroundings. FIG. 9 is a flowchart for explaining the operation of the control device of the life diagnosis apparatus for the surge protection device.

  FIG. 1 shows an impulse life characteristic example 1 of a surge protection device using zinc oxide (relationship between the number of times the surge protection device is used and the impulse current value). In FIG. 1, the horizontal axis represents the service life [times], and the vertical axis represents the surge current value [kA]. Further, “♦” indicates characteristics when the surge wave tail length is 20 μsec, “■” marks indicate characteristics when the surge wave tail length is 100 μsec, and “▲” marks indicate characteristics when the surge wave tail length is 1000 μsec.

  As shown in FIG. 1, the impulse life characteristic of the surge protection device is that the life is reduced to about 1/10 to 1/100 when the surge current value is doubled. On the contrary, if the surge current value is halved, the lifetime increases 10 to 100 times. Therefore, to determine the life of a surge protection device, it is essential to consider the magnitude of the surge current, and it is clear that it is not a simple proportional relationship.

According to the location indicated by the straight line graph on the log-log graph of FIG. 1, assuming that the surge current value is I and the upper limit of the number of times the surge protection device can be used is N, the relationship of the following equation (1) is approximately established.
LogN = −αLogI + C (1)
Where −α is the slope of the approximate line in the log-log graph,
C: Constant

here,
C = αLog (I ₀ ) + Log (N ₀ )
Where I ₀ : current value for comparison
N ₀ : Suppressing the number of surge protection devices at I ₀ , equation (1) is
Log (N / N ₀ ) = − αLog (I / I ₀ ) (2)
So,
N / N ₀ = (I / I ₀ ) ^−α (3)
It is clear that

In Figure 1, for example, when a surge wave tail length is 20 .mu.sec, the current value is 28kA If durability times is 10 ³ times, the current value is 10 ² times for 42KA. Therefore, if I ₀ is 28 kA in equation (2),
α = 5.6788 ...
It becomes.

  On the other hand, FIG. 2 shows an impulse life characteristic example 2 (relation between impulse current and surge wave tail length (impulse length)) of a surge protection device using zinc oxide. In FIG. 2, the horizontal axis represents the surge wave tail length [μsec], and the vertical axis represents the current value [kA]. In addition, “◆” indicates a service life of 2.E + 00 (twice), “■” indicates a service life of 1.E + 01 (10), and “▲” indicates a service life of 1.E + 02 (100 Times), “●” mark has a service life of 1.E + 03 times (1,000 times), “◇” mark has a service life of 1.E + 04 times (10,000 times), and “○” mark has a service life of 1.E + 05 times. (100,000 times), “□” mark indicates the characteristics when the service life is 1.E + 06 times (million times). 2, the exponent base 10 is represented by the symbol E and the multiplication symbol “×” is omitted, for example, 1. × 10 (+01 power) is represented by 1.E + 01. It is.

According to the linear graph on the logarithmic graph of FIG. 2, when the surge current value is I and the duration of the surge waveform (also called the surge wave tail length) is T, the relationship of the following equation (4) is approximately Holds.
Log T = −β Log I + D (4)
Where -β is the slope of the approximate line in the log-log graph
D: Constant

here,
D = βLog (I ₀ ) + Log (T ₀ )
However, T ₀ : Duration of surge waveform as a reference for comparison
I ₀ : If it is the current value at T ₀ ,
(T / T ₀ ) = (I / I ₀ ) ^−β (5)
And
I = (T / T ₀ ) ^{−1 / β} · I ₀ (6)
Is established.

In FIG. 2, for example, in the case of a service life of 2 times (2E + 0), if the surge current duration T ₁ is 20 μsec, the current value I ₁ is 100 kA, but if the surge current duration T is 100 μsec, the current value I is 30 kA. However, it will be unbearable. Therefore, in this case, according to the above equation (5),
β = 1.367 ...
It becomes.

Assuming that the above equation (3) is established for a surge current having a duration T ₀ = 20 μsec, the above equation (6) is used for a surge current having a duration other than T _0. Substituting I by I · (T / T ₀ ) ^{1 / β} in (3), the following equation (7) is established.
N / N ₀ = (T / T ₀ ) ^{−α / β} · (I / I ₀ ) ^−α (7)

However, α is the data of two points (N ₀ , I ₀ ), (N ₁ , I ₁ ) on the graph of the surge current duration T ₀ in FIG.
α = − (Log (N ₁ / N ₀ )) / Log (I ₁ / I ₀ ) (8)
Is the value.

Moreover, beta 2 points on the graph of the surge life count _{N 0} in FIG. _{2 (T 0, I 0)} , to the data of _{(T 2, I} 2),
β = − (Log (T ₂ / T ₀ )) / Log (I ₂ / I ₀ ) (9)
Is the value.

Here, N ₀ , I ₀ , and T ₀ are values common to the above formula (8) and the above formula (9).

  The right side of the above equation (7) represents the ratio of the number of times the surge protection device has been used to the standard use number when a surge is applied due to the surge current value I and its duration T. Therefore, this reciprocal is an amount proportional to the damage given to the surge protection device by this current value I and its duration T.

  The inventor does not simply store and integrate the product of the current value and the duration of the surge, but rather stores the accumulated value obtained by performing the correction calculation based on the duration T to cause damage to the surge protection device. Focusing on the fact that the accumulated amount can be expressed more accurately, the device for diagnosing the life of the surge protection device according to the present invention is realized.

  Certainly, according to the location shown in FIG. 1, even a surge that can withstand 1,000,000 times may be broken in about 1 to 10 times if the current value becomes 10 times. Therefore, it is impossible to determine the life of a surge protection device at all with the simple method of integrating surge current values and the cumulative calculation method of effective and average surge values based on the area of the surge current waveform considering the duration of the surge. Is clear.

  By the way, if the current sensor at the input section becomes saturated with a huge lightning surge and only a value smaller than the actual current value can be detected, the subsequent correction calculation also becomes meaningless, so the input section will not be saturated even with an excessive surge current. It is necessary to consider that.

  In the device for diagnosing the life of the surge protection device according to the present invention, in addition to the correction of the current value, the lightning surge of up to 50 kA is measured with a low-cost current transformer without saturating the magnetic material. And a current transformer in which a gap is provided in a part of the core. Such air-core CT is suitable because it does not saturate, but since there is no structure that can be easily clamped to an electric wire, the present inventor is in the stage of designing the life diagnosis device for surge protection device of the present invention. A special CT was produced.

  Also, the peak value of the measured current is attenuated slowly exponentially, so that even a relatively slow control unit guarantees sufficient time for data processing during the slow sampling period. .

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A surge protection device life diagnosis apparatus according to the present invention will be described below in detail with reference to the illustrated embodiments.

[First Embodiment]
FIG. 3 is a block diagram showing the overall configuration of the surge protection device life diagnosis apparatus according to the first embodiment of the present invention.

  As shown in FIG. 3, the life diagnosis apparatus for surge protection device according to the first embodiment includes a first surge detection unit U1, a second surge detection unit U2,..., An Nth surge detection unit Un, -A processing device 1 for receiving a signal from the n-th surge detection unit U1, U2, ..., Un and diagnosing the life of the surge protection device, and a display device 2 for displaying a diagnosis result of the processing device 1 are provided. .

  The first to nth surge detection units U1, U2,..., Un receive a signal representing a surge current from a current sensor (current transformer CT shown in FIG. 4) that detects the surge current flowing in the surge protection device. The input unit 11, the peak hold unit 12 that holds the peak value of the analog signal that represents the surge current from the input unit 11, and the analog signal that represents the peak value of the surge current held by the peak hold unit 12 And an attenuating portion 13 for attenuating.

  The processing device 1 is A / D-converted by an A / D converter 1a for A / D-converting an analog signal representing the peak value of the surge current output from the attenuation unit 13, and the A / D converter 1a. Based on the peak value of the surge current, the calculation unit 1b that calculates a value corresponding to the damage amount that the surge protection device received by the surge current, and the damage that the surge protection device calculated by the calculation unit 1b received by the surge current An integration unit 1c that integrates a value corresponding to the amount, an integrated value determination unit 1d that determines whether or not the integrated value integrated by the integration unit 1c is greater than or equal to a preset threshold, and an integration integrated by the integration unit 1c When the integrated value determination unit 1d determines that the value is equal to or greater than the threshold, the notification unit 1e that notifies that the surge protection device has reached the end of its life is provided.

  FIG. 4 shows a specific example of the circuit of the input unit 11, the peak hold unit 12 and the attenuation unit 13 of the surge protection device life diagnosis apparatus of the first embodiment.

  The input unit 11 includes a shunt resistor R1 connected between output terminals of a current transformer CT as an example of a current sensor that detects a surge current flowing in the surge protection device, and a resistor having one end connected to one end of the shunt resistor R1. R2 includes a diode D1 having an anode connected to the other end of the resistor R2 and a cathode connected to + 15V, and a diode D2 having a cathode connected to the other end of the resistor R2 and an anode connected to −15V. The other end of the shunt resistor R1 is connected to the ground GND. In this embodiment, the shunt resistor R1 is a semi-fixed resistor having a maximum resistance value of 1 kΩ, and the resistor R2 is 3.3 kΩ.

  The peak hold unit 12 includes a differential amplifier AMP1 having a non-inverting input terminal connected to the other end of the resistor R2, a resistor R3 having one end connected to the output terminal of the differential amplifier AMP1, and the other end of the resistor R3. A diode D3 having an anode connected thereto, a peak hold capacitor C1 having one end connected to the cathode of the diode D3 and the other end connected to the ground GND, and a power input terminal connected to + 15V of the differential amplifier AMP1 And a capacitor C11 connected between the ground GND and a capacitor C12 connected between the power input terminal to which −15V of the differential amplifier AMP1 is connected and the ground GND. The cathode of the diode D3 is connected to the inverting input terminal of the differential amplifier AMP1. In this embodiment, the resistor R3 is 220Ω and the capacitor C1 is 0.01 μF.

  The attenuating unit 13 includes a differential amplifier AMP2 in which the cathode of the diode D3 is connected to the non-inverting input terminal, and a discharging resistor R4 connected between the non-inverting input terminal of the differential amplifier AMP2 and the ground GND. And a capacitor C21 connected between the power supply input terminal connected to + 15V of the differential amplifier AMP2 and the ground GND, and a power supply input terminal connected to −15V of the differential amplifier AMP2 and the ground GND. And a connected capacitor C22. The output terminal of the differential amplifier AMP2 is connected to the inverting input terminal. In this embodiment, the resistor R4 is 10 MΩ.

  The output terminal of the differential amplifier AMP2 of the attenuation unit 13 is connected to the input terminal of the processing apparatus 1, and the other input terminal of the processing apparatus 1 is connected to the ground GND.

  As shown in FIG. 4, the current flowing through the surge current path SL of the ground circuit to be measured is a current transformer CT with a gap using a semicircular or U-shaped core (or a clamp CT having a gap). ) And the peak value of the surge current is held by the peak hold unit 12.

The permeability μ _y of the core of the current transformer CT with the gap and the permeability μ _{X of the} core itself have the relationship of the following expression (10). The permeability decreases as the gap increases, but the sensitivity decreases. It becomes difficult to saturate even with a large current.
μ _y = 1 / (1 / μ _X + L _GAP / L) (10)
L: Magnetic path length of the core part
L _GAP : Magnetic path length of the gap

  In the input unit 11, the current on the secondary side of the current transformer CT is converted into a voltage through the shunt resistor R1, and the peak value is detected and held by the differential amplifier AMP1 in the next stage. It is desirable that the current sensor faithfully reproduces the measurement-symmetrical surge current waveform. The input unit 11 may be a current transformer that does not saturate even with a large current, such as a Rogowski coil or air core CT.

  In FIG. 4, the peak value detected by the differential amplifier AMP1 is unipolar, but actually there is another circuit to cover the case of a negative surge current (the same applies to the processing apparatus 1 side). . The peak value detected and held by the differential amplifier AMP1 is slowly attenuated by the discharge resistor R4 of the attenuating unit 13 to prepare for the next surge input.

  In a design example in which cost is not important, when the processing apparatus 1 samples data, the held value may be reset by the sampling pulse.

  However, in order to supply this sampling pulse to the outside of the processing apparatus 1, a dedicated interface circuit is required. In this first embodiment, the damage of the surge protection device due to the lightning surge is cumulatively calculated, and observation according to the frequency of the lightning surge is sufficient, so the peak held by the simple discharge resistor R4 in consideration of the cost. The value is attenuated slowly and naturally to clear the data. The A / D converter 1 of the processing apparatus 1 samples data at a rate of once per 1 msec, but the peak value decays over several tens of msec, so that the peak value of the surge current can be sampled without a large error.

  In the device for diagnosing the life of the surge protection device according to the first embodiment, when a surge current is input to any one of the input portions 11 of the first to n-th surge detection units U1, U2,. The peak hold unit 12 holds the peak value of the analog signal representing the surge current, and the attenuation unit 13 exponentially attenuates the analog signal representing the peak value of the held surge current.

  The processing device 1 performs A / D conversion on the analog signal representing the peak value of the surge current output from the attenuation unit 13 by the A / D converter 1a.

  Next, in the calculation unit 1b, based on the peak value of the surge current A / D converted by the A / D converter 1a, the surge protection device corresponds to the amount of damage received by the surge current by the following equation (11). The value Y to be calculated is calculated.

ただし、Ｉ_IN ： サージ電流のピーク値を表すデジタル値
Ｉ_０ ： 基準電流値
α ： サージ防護デバイスによって決まる定数

However, I _IN : Digital value indicating the peak value of surge current I ₀ : Reference current value α: Constant determined by the surge protection device

  Here, α is a constant determined by the surge protection device using the above equation (8).

  Next, the value Y corresponding to the amount of damage that the surge protection device calculated by the calculation unit 1b has received by the surge current is integrated by the integration unit 1c.

  Then, the integrated value determining unit 1d determines whether or not the integrated value integrated by the integrating unit 1c is equal to or greater than a preset threshold value.

  Next, when the integrated value determining unit 1d determines that the integrated value integrated by the integrating unit 1c is equal to or greater than the threshold value, information indicating that the surge protection device has reached the end of its life is output from the notification unit 1e to the display device 2. .

  FIG. 5 shows the configuration of the processing apparatus 1 and its periphery. As shown in FIG. 5, the processing device 1 includes an A / D converter 1a, a CPU (Central Processing Unit), a memory, and an I / F. The CPU, the memory, and the I / F F functions as the calculation unit 1b, the integration unit 1c, the integration value determination unit 1d, and the notification unit 1e. As described above, the processing apparatus 1 includes a low-cost microcomputer and an input / output circuit, and the data sampling by the A / D converter 1a is as low as 1 kHz.

  When the processing device 1 only needs to operate at the time of surge detection, the CPU does not need to always calculate, so it tries to save power using the sleep mode, or stores data in a nonvolatile memory, and only when a surge is detected. The power of the processing apparatus 1 may be supplied.

  Regardless of the above equation (11), a method of accumulating a large current value with a large weight by using a similar calculation formula can perform life diagnosis with higher accuracy than accumulative calculation by simple addition.

  FIG. 6 is a flowchart for explaining the operation of the processing device 1 of the life diagnosis device for the surge protection device.

  First, when the process is started, it is determined whether or not there is a surge input in step S1 shown in FIG. 6. If it is determined that there is a surge input, the process proceeds to step S2, while if it is determined that there is no surge input, step S1 is repeated. . It is assumed that the integrated value is previously reset to zero before this process starts.

In step S2, the calculation unit 1b calculates the above formula (11) based on the surge current peak value I _IN , and then the calculation result is integrated by the integration unit 1c.

  Next, it progresses to step S3, it is determined by the integrated value determination part 1d whether the integrated value integrated by the integrating part 1c is more than the preset threshold value, and it is that the integrated value is more than the preset threshold value. If it determines, while progressing to step S4, if it determines with an integrated value being less than the preset threshold value, step S4 will be skipped.

  In step S4, the notification unit 1e notifies that the surge protection device has reached the end of its life.

  Next, the process proceeds to step S5, where it is determined whether or not the surge is continuing. If it is determined that the surge is continuing, step S5 is repeated. If it is determined that the surge is not continuing, the process proceeds to step S1. Return.

  As described above, when the processing apparatus 1 accumulates the results of the calculation according to the above formula (11) from the peak value information of the surge current obtained by the peak hold unit 12, and exceeds a certain threshold value, Outputs an alarm based on the judgment of the life of the surge protection device.

  According to the surge protection device life diagnosis apparatus having the above-described configuration, the surge protection device can be used based on the impulse life characteristic example 1 (relationship between the number of times the surge protection device can be used and the impulse current value) shown in FIG. The constant α to be determined is determined, and the value Y corresponding to the amount of damage that the surge protection device has received by the surge current is calculated by the calculation unit 1b using the above equation (11). Since the accumulated amount can be accurately obtained, accurate life determination in consideration of the impulse life characteristics of the surge protection device can be performed at low cost.

  By applying the surge diagnosis device life diagnosis device above, it is possible to perform integration with an appropriate weighting applied to the magnitude of the current. Therefore, the life diagnosis device simply adds the current value or counts the number of pulses. More accurate life diagnosis (judgment) is possible.

  In addition, since the analog signal representing the peak value of the surge current held by the peak hold unit 12 is A / D converted by the A / D converter 1a, the time is extended and transmitted to the processing device 1. Even if the processing operation of A / D conversion or calculation is slow, it can be used sufficiently, and an expensive A / D converter for high-speed sampling or a DSP (Digital Signal Processor) capable of high-speed processing is used. There is no need, and the cost can be reduced.

  An analog signal representing the peak value of the surge current output from the peak hold unit 12 is exponentially attenuated by the attenuating unit 13, so that even a processing apparatus having a relatively slow operation can sufficiently perform during the slow sampling period. Time for performing proper data processing can be secured.

  Further, when the integrated value determining unit 1d determines that the integrated value integrated by the integrating unit 1c is equal to or greater than the threshold, the notification unit 1e notifies the surge protective device that the surge protection device has reached the end of its life. Maintenance such as replacement can be performed quickly before it breaks.

  In addition, by detecting the surge current flowing through the surge protection device with a current transformer CT having a gap in a part of the core forming the magnetic path, a large current of lightning surge can be generated with a low-cost current transformer CT. It can be measured without saturation. In addition, since a core with low permeability and air gap is used for the current sensor, it is possible to accurately detect surge currents even at high currents without saturation, so the effect of appropriate weighting on the magnitude of the current The life can be determined correctly without being hindered.

[Second Embodiment]
In the second embodiment, correction calculation based on the duration of surge is added to the first embodiment.

  FIG. 7 shows the overall configuration of the surge protection device life diagnosis apparatus according to the second embodiment of the present invention, and FIG. 8 shows the control section of the surge protection device life diagnosis apparatus and its peripheral configuration. The device for diagnosing the life of surge protection device according to the second embodiment includes the configurations of the first to n-th surge detection units U1, U2,..., Un and the second A / D converter 1f and the calculation unit 1b of the control device. Except for the processing, it has the same configuration as the surge diagnosis device life diagnosis apparatus of the first embodiment.

  As shown in FIG. 7, the first to n-th surge detection units U1, U2,..., Un of the surge protection device life diagnosis apparatus of the second embodiment include an input unit 11, a peak hold unit 12, and an attenuation unit 13, respectively. In addition, the level comparator 14 that compares the level of the surge current output from the input unit 11 with a preset level determination value, and the level comparator 14 causes the surge current level to exceed the level determination value. It has the integrator 15 as an example of the timer for measuring the continuation time which continued.

  The level comparator 14 and the integrator 15 constitute a duration measuring unit. In this embodiment, the integrator 15 is used as a timer. However, the present invention is not limited to this, and a counter circuit or the like may be used.

  In addition, the control device 1 includes a second A / D converter 1 f that performs A / D conversion on an analog signal that represents the duration time output from the integrator 15.

  Further, as shown in FIG. 8, the output terminal of the attenuation unit 13 is connected to the reset terminal of the integrator 15.

  In the device for diagnosing the life of the surge protection device according to the first embodiment, when a surge current is input to any one of the input portions 11 of the first to n-th surge detection units U1, U2,. The peak hold unit 12 holds the peak value of the analog signal representing the surge current, and the attenuation unit 13 exponentially attenuates the analog signal representing the peak value of the held surge current.

  When the level comparator 14 compares the surge current level output from the input unit 11 with a preset level determination value, and the level comparator 14 causes the surge current level to exceed the level determination value. The output voltage of the level comparator 14 is integrated by the integrator 15. As a result, an analog signal representing the duration is output from the integrator 15.

  The analog signal representing the peak value of the surge current output from the attenuation unit 13 is A / D converted by the A / D converter 1a of the processing device 1, and the integrator 15 is converted by the A / D converter 1f. A / D conversion is performed on the analog signal representing the duration time output from.

  And in the calculating part 1b, the digital value showing the peak value of the surge current A / D converted by the A / D converter 1a and the duration of the surge current A / D converted by the A / D converter 1f are shown. Based on the digital value, the value Y corresponding to the amount of damage received by the surge protection device due to the surge current is calculated by the following equation (12).

ただし、 Ｉ_IN ： サージ電流のピーク値を表すデジタル値
Ｉ_０ ： 基準電流値
α ： サージ防護デバイスによって決まる定数
Ｔ_IN ： サージ電流の継続時間を表すデジタル値
Ｔ_０ ： 基準継続時間
γ ： サージ防護デバイスによって決まる定数

However, I _IN : Digital value representing the peak value of surge current
I ₀ : Reference current value
α: Constant determined by the surge protection device
T _IN : Digital value indicating the duration of surge current
T ₀ : Reference duration
γ: Constant determined by the surge protection device

  Here, γ is α / β, α is a constant determined by the surge protection device using the above equation (8), and β is a constant determined by the surge protection device using the above equation (9).

  Next, the value Y corresponding to the amount of damage that the surge protection device calculated by the calculation unit 1b has received by the surge current is integrated by the integration unit 1c.

  Then, the integrated value determining unit 1d determines whether or not the integrated value integrated by the integrating unit 1c is equal to or greater than a preset threshold value.

  Next, when the integrated value determining unit 1d determines that the integrated value integrated by the integrating unit 1c is equal to or greater than the threshold value, information indicating that the surge protection device has reached the end of its life is output from the notification unit 1e to the display device 2. .

  FIG. 9 is a flowchart for explaining the operation of the processor 1 of the surge protection device life diagnosis apparatus.

  First, when the process starts, it is determined whether or not there is a surge input in step S11 shown in FIG. 9, and if it is determined that there is a surge input, the process proceeds to step S12. If it is determined that there is no surge input, step S11 is repeated. . It is assumed that the integrated value is previously reset to zero before this process starts.

In step S12, the calculation unit 1b calculates the above expression (11) based on the surge current peak value I _IN and the duration T _IN , and then the calculation result is integrated by the integration unit 1c.

  Next, it progresses to step S13, it is determined by the integrated value determination part 1d whether the integrated value integrated by the integration part 1c is more than a preset threshold value, and it is that an integrated value is more than a preset threshold value. If it determines, it will progress to step S14, On the other hand, if it determines with an integrated value being less than the preset threshold value, step S14 will be skipped.

  In step S14, the notification unit 1e notifies that the surge protection device has reached the end of its life.

  Next, proceeding to step S15, it is determined whether or not the surge is continuing. If it is determined that the surge is continuing, step S15 is repeated, while if it is determined that the surge is not continuing, the process proceeds to step S11. Return.

  As described above, the operation of the processing apparatus 1 is substantially the same as in the case of the first embodiment, but the above equation (12) is obtained from the peak value information and the duration information of the surge current obtained by the peak hold unit 12. If the result of the calculation is accumulated and a certain threshold value is exceeded, it is determined that the life of the surge protection device has been reached and an alarm is output.

  In the second embodiment, the peak value information of the surge current becomes zero after a certain time, and the integrator 15 that counts the duration of the surge current is reset by this signal.

  The surge protection device lifetime diagnosis apparatus of the second embodiment has the same effect as the surge protection device lifetime diagnosis apparatus of the first embodiment.

  Further, when the value Y corresponding to the amount of damage received by the surge protection device due to the surge current is calculated by the calculation unit 1b, the surge protection is performed by performing correction according to the duration of the surge current using the above equation (12). Accumulated amount of damage to the device can be calculated more accurately.

  Further, since the integrator 15 measures the duration during which the level of the surge current has exceeded the level judgment value by the level comparator 14, the duration of the surge current can be easily measured with a simple configuration. .

  In the first and second embodiments, information indicating that the surge protection device has reached the end of its life is output from the notification unit 1e to the display device 2 and an alarm is displayed on the display device 2. The means for notifying the information indicating that it has reached the limit is not limited to this, and it may be notified that the surge protection device has reached the end of its life by other means such as voice or alarm sound.

  Although specific embodiments of the present invention have been described, the present invention is not limited to the first and second embodiments described above, and various modifications can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Processing apparatus 1a ... A / D converter 1b ... Operation part 1c ... Accumulation part 1d ... Integration value determination part 1e ... Notification part 1f ... A / D converter 2 ... Display apparatus 11 ... Input part 12 ... Peak hold part 13 ... Attenuator 14 ... Level comparator 15 ... Integrator U1, U2, ..., Un ... First, second, ..., nth surge detection unit

Claims (7)

A current sensor for detecting a surge current flowing in the surge protection device;
An A / D converter for A / D converting the surge current detected by the current sensor;
Based on the peak value of the surge current A / D converted by the A / D converter, a calculation unit that calculates a value corresponding to the amount of damage that the surge protection device has received by the surge current;
An accumulating unit for accumulating a value corresponding to the amount of damage received by the surge current by the surge protection device calculated by the calculating unit;
An integrated value determination unit that determines whether the integrated value integrated by the integration unit is greater than or equal to a preset threshold value;
The calculation unit has a value Y corresponding to the amount of damage that the surge protection device has received by the surge current,

However, I _IN : Digital value representing the peak value of the surge current I ₀ : Reference current value α: A surge diagnosis device life diagnosis apparatus characterized by calculation based on a constant determined by the surge protection device. In the life diagnosis apparatus of the surge protection device according to claim 1,
A peak hold unit for holding a peak value of the surge current detected by the current sensor;
The A / D converter performs A / D conversion on an analog signal representing a peak value of the surge current held by the peak hold unit, and is a device for diagnosing the life of a surge protection device. In the life diagnosis apparatus of the surge protection device according to claim 2,
An apparatus for diagnosing surge protection device life, comprising an attenuation unit for exponentially attenuating an analog signal representing the peak value of the surge current output from the peak hold unit. In the life diagnosis apparatus of the surge protection device according to any one of claims 1 to 3,
A surge comprising an informing unit for informing that the surge protection device has reached the end of its life when the integrated value determining unit determines that the integrated value integrated by the integrating unit is equal to or greater than the threshold value. Lifetime diagnosis device for protective devices. In the life diagnosis apparatus of the surge protection device according to any one of claims 1 to 4,
A duration measuring unit for measuring the duration of the surge current detected by the current sensor;
The arithmetic unit, based on the duration measured by the duration measurement unit, a value Y corresponding to the amount of damage that the surge protection device has received by the surge current,

However, I _IN : Digital value indicating the peak value of the surge current
I ₀ : Reference current value
α: Constant determined by the above surge protection device
T _IN : Duration of the above surge current
T ₀ : Reference duration
γ: A device for diagnosing the life of a surge protection device, characterized in that the calculation is performed with a constant determined by the surge protection device. In the life diagnosis apparatus of the surge protection device according to claim 5,
The duration measuring unit is
A level comparator that compares the level of the surge current detected by the current sensor with a preset level determination value;
A life diagnosis apparatus for a surge protection device, comprising: a timer for measuring the duration time during which the level of the surge current has continued to exceed the level determination value by the level comparator. In the life diagnosis apparatus of the surge protection device according to any one of claims 1 to 6,
The life sensor for a surge protection device according to claim 1, wherein the current sensor is a current transformer in which a gap is provided in a part of a core forming a magnetic path.

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