JPH07123330B2 - Conductive part overheat detection notification method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive part overheat detection and notification method for detecting and reporting the occurrence of abnormal overheat of a conductive part such as a connection part of electric power equipment.

[0002]

2. Description of the Related Art Conventionally, in power equipment such as power receiving and transforming equipment, the temperature of a conductive portion such as a connecting portion and a contact portion of a main circuit portion thereof exponentially rises due to a sudden abnormality and an aged abnormality, During energization, a state of abnormal overheating that exceeds the normal temperature rise may occur locally.

In order to detect the occurrence of this abnormal overheat, conventionally, a thermo label is provided on the conductive part or a thermo paint is applied, and the thermo is detected by, for example, a regular inspection about once a month. The label and thermo paint are visually inspected for discoloration and checked for any abnormalities.

[0004]

When detecting the occurrence of abnormal overheat by visual inspection as in the prior art, there is a problem in that it requires a regular inspection by an operator and labor is not saved. It will be detected based on the change and experience of the worker, and since it is difficult to perform frequent inspections, early detection cannot be performed, and detection of sudden abnormal overheating due to sudden abnormality is delayed. There is also a problem that is likely to occur.

In addition, it is difficult to quantitatively grasp the overheated state, and it is necessary to visually check the complicated structure in which obstacles such as other members in the device prevent the conductive portion from being detected. In some cases, it is difficult to inspect and cannot be detected.

The present invention detects the occurrence of abnormal overheating of a conductive portion by means of a method suitable for automation based on the detection of energization current and temperature, and also notifies the user of the occurrence of abnormal overheating, and also predicts the time when it will reach a dangerous state. The purpose is to notify you.

[0007]

In order to achieve the above-mentioned object, in the method for detecting and detecting the overheat of a conductive portion of the present invention, the current flowing through the conductive portion, the temperature and the outside air temperature are detected periodically,
The predicted value of the temperature change amount that depends on the energization of the conductive part at each time is calculated from the detected current at each time, and the temperature obtained by removing the outside air temperature from the detected temperature at each time is the specified overheat caution temperature or overheat higher than that temperature. The time to reach the judgment temperature is detected. Then, when the temperature reaches the overheat determination temperature, the saturation value of the temperature change amount is calculated from the overheat caution temperature, the time when the overheat determination temperature is reached, and the predicted value, and the energization is performed from the time function formula of the temperature having the saturation value as a coefficient. The time at which the dependent temperature reaches the set dangerous temperature is calculated, and the occurrence of abnormal overheat and the time at which the dangerous temperature is reached are reported.

[0008]

In the case of the conductive portion overheat detection / informing method of the present invention configured as described above, abnormal overheating occurs, the temperature of the conductive portion rises, and the temperature obtained by removing the outside air temperature from the temperature of the conductive portion is overheated. When the temperature and the overheat determination temperature are reached, the time when each of the temperatures is reached is detected.

Further, when the temperature reaches the overheat determination temperature, the predicted value of the temperature change amount based on the detected current at that time and the saturation value (final value) of the increase in the temperature change amount based on the energizing current are calculated from both detected times. The saturation value is used to calculate and predict the time at which the temperature depending on the energization of the conductive portion reaches the dangerous temperature. Then, the occurrence of abnormal overheating is notified, and the time at which the device continues to be used as it is and reaches a dangerous state is notified.

In this case, for temperature detection, automatic measurement using a temperature sensor is possible, and since each calculation and notification process can be automated using a computer device, conventional thermolabels and thermopaints can be used. By eliminating manual work such as visual inspection of discoloration, abnormal overheating can be detected and notified without relying on experience or intuition, and the time during which continuous use can be calculated and notified. Then, by shortening the cycle of temperature detection, early detection can be performed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. In this embodiment, as shown in FIG. 2, for example, the connecting portion of the conductors 1 and 2 of the main circuit portion of the power receiving and transforming equipment is the conductive portion 3 to be detected.

The conductive portion 3 is provided on the support insulator 4,
Non-contact type conductive part temperature sensor with upper radiation thermometer 5
The temperature is detected by the non-contact method.

The current flowing through the conductors 1 and 2 (main circuit current) is detected by a current transformer (CT) 6, and the outside air temperature around the conductive portion 3 is detected by an outside air temperature sensor 7 having a resistance temperature detector. To be done. In addition, 8 and 9 show the output cables of the sensors 5 and 7, and 10 shows the secondary cable of the current transformer 6.

The cables 8, 9 and 10 are connected to the sensor input section 12 and the current input section 13 of the conductive part overheat detection and notification device 11 of the computer construction of the monitoring panel shown in FIG. Analog signal of the input section 1
2 and the analog signal of the detected current of the current transformer 6 is transmitted to the input unit 13.

Further, the signals of the input sections 12 and 13 are sent to the A / A via the multiplexer 14 every predetermined sampling period.
The data is supplied to the D converter 15, converted into digital data, and sent to the arithmetic processing unit 16 formed by the CPU.

Then, the arithmetic processing section 16 monitors the occurrence of abnormal overheating of the conductive section 3 based on the calculation of the predicted value of the temperature change amount depending on the energization at each detection time, which will be described later, and the detection of the time when the set temperature is reached. Then, when the occurrence is detected, the overheat detection output unit 17 is notified of the time when the occurrence and the dangerous temperature are reached, and the output unit 17 supplies a contact signal or the like for an alarm to a notification device or the like outside the device.

Next, the temperature characteristic of the conductive portion 3 will be described. (1) Temperature rise characteristic Due to Joule heat generation based on the conduction current I (A), the temperature change characteristic of the conductive portion 3 with the elapsed time t (unit: H: hours) from the start of conduction is almost the solid line a in FIG. It becomes an exponential rising characteristic of.

The solid line a indicates the time-dependent temperature change amount Δθ (° C.) = Δθ _m when the energizing current I has the maximum value I _m , and this change amount Δθ _m and the elapsed time t are as follows. Number 1
It has the relation of the formula of.

[0019]

[Formula 1] Δθ _m = Δθ _max · {1-exp (-t / T)}

In the equation, Δθ _max is the maximum saturation value of temperature rise (° C.), and T is the thermal time constant, which are determined by the heat conduction / heat dissipation characteristics of the conductive portion 3 based on the temperature rise test data. Further, the amount of temperature change Δθ ₀ after the energization of the energizing current I = I ₀ (<I _m ) can be expressed by the following formula 2 with I _m as the reference.

[0021]

[Number 2] _{Δθ 0 = Δθ max · (I} 0 / I m) k · {1-exp (-t / T)}

Note that k in the equation is a constant of the current conversion index and is determined by the temperature rise test data. Further, assuming that the energizing current I increases from I ₀ to I _n at n as shown by the solid line b in FIG. 3, the temperature change amount after the increase Δθ = Δθ
_n is represented by the following equation 3 with the temperature variation Δθ = Δθ _0n obtained from I ₀ at the time of n.

[0023]

Equation 3] _{Δθ n = {Δθ max · (} I n / I m) k -Δθ 0n} · {1-exp (-t / T)} + Δθ 0n

(2) Temperature drop characteristic Due to the decrease (interruption) of the conduction current I, the temperature change characteristic of the conductive portion 3 with the lapse of time t becomes an exponential function characteristic indicated by a solid line c in FIG. The solid line c indicates the subsequent temperature change amount Δθ = Δθ _m ^* when the current is cut off after reaching the maximum Δθ _max of the saturation value of the temperature rise at the energizing current I = I _m ,
The amount of change Δθ _m ^* and the elapsed time t from the current interruption have the relationship of the following equation (4).

[0025]

[Formula 4] Δθ _m ^* = Δθ _max · exp (-t / T)

When the energizing current I = I _m reaches Δθ _max and then decreases to I = I ₀ , the temperature change Δθ = Δθ ₀ ^* after this change is calculated as follows using the current I _m. It can be shown by the formula of Formula 5.

[0027]

Equation 5] ^{_{Δθ 0 * = Δθ max · (}} I 0 / I m) k · exp (-t / T) + Δθ max · {1- (I 0 / I m) k}

Further, as indicated by the solid line d in FIG. 4, I ₀
Assuming that the conduction current I decreased to _n is further decreased to n at _n , the temperature change amount Δθ = Δθ _n ^* after the decrease is given by the following number, where Δθ _0n ^* is the temperature change amount obtained from I ₀ at _n ^. It is shown by the formula of 6.

[0029]

## EQU6 ## Δθ _n ^* = [Δθ _0n ^* −Δθ _max · {1- (I _n / I _m ) ^k ] · expp (−t / T) + Δθ _max · {1- (I _n / I _m ) ^k }

Next, the processing of the arithmetic processing section 16 will be described. First, the temperature change characteristic based on the energizing current at each detection time determined by the sampling period can be predicted by the equation (3) or (6).

When contact failure occurs in the conductive portion 3 due to loosening of the mounting bolts and the like, and the contact resistance increases, the Joule heat increases with this increase and the saturation value {Δθ of the temperature rise in the equation (3). _max · (I _n / I _m ) ^k −Δθ _0n } becomes abnormally large. In this case, the temperature change characteristic is, for example, the rising characteristic indicated by the solid line e in FIG.

The solid line e in FIG. 5 indicates I when the energizing current is n.
₀ changes to I _n, shows a case where the temperature is rapidly increased by the subsequent overheating. On the other hand, the temperature (detected temperature) of the conductive portion 3 detected by the temperature sensor 5 is almost the temperature obtained by adding the outside air temperature to the temperature depending on the energizing current.

When the detected temperature of the conductive portion 3 detected by the temperature sensor 5 is θ and the outside air temperature detected by the temperature sensor 7 is θ _a , the difference (θ−θ _a =) θ _d is changed from the rising change. The occurrence of abnormal overheating can be detected.

That is, θ _L , θ _H (θ _L <
θ _H ) is set as the overheat caution temperature and the overheat determination temperature, and the time t _l (n hours when the difference θ _L is reached is detected by monitoring and detecting whether or not the difference θ _d reaches θ _L , θ _H. Can be detected as the occurrence of abnormal overheating.

Further, the time at which the difference θ _d reaches θ _L , θ _H is set to t _l , t _h , and t = calculated from the equation (3)
If the predicted value of the temperature change amount Δθ of t _l is Δθ _nl ,
Assuming that the saturation value of the temperature rise in the equation (1) is the unknown Δθ _x , the following equation (7) is established.

[0036]

Equation 7] θ _H = Δθ _x · _{[1-exp {- (t h} -t l) / T} ] + [Delta] [theta] _nl

Then, when Δθ _x is obtained from the equation (7),
The time when the set dangerous temperature θ _LMT is reached is obtained by the following equation (time function equation) based on the equation (7).

[0038]

T _LMT = −L _n {1- (θ _LMT −Δθ _nl ) / Δθ _x } · T + t _l

L _n in the equation is a natural logarithm operator.

Therefore, the arithmetic processing unit 16 makes each detection time
According to the flow chart of FIG.
Alternatively, the temperature change amount Δθ according to the equation (6) is calculated. Note that FIG.
S1 to S19 indicate each step of the processing, and the processing contents thereof are set as shown in Table 1.

[0041]

[Table 1]

Further, in order to enable early detection of sudden abnormal overheat due to sudden abnormality, the sampling period is set to 1 / 6H (10 minutes) in FIG. 6, and frequent detection is performed.

Then, the temperature change amount Δθ and the energizing current I at each detection time t and the detection time t−1 immediately before them are Δ.
Assuming θ _t , I _t and Δθ _t-1 , I _t-1 , initial setting of t = 0 and Δθ _t-1 = 0 by S1 of FIG. 6 at the start of energization. At the first detection time after 1 / 6H has elapsed from this setting, t = 1 / 6H is set in S4, and Δθ _t is calculated from I _{t at} that time.

At this time, since I _t increases from the start of energization, Δθ _0n = Δθ _t-1 =
Δθ _t is calculated as 0. Next, at the second detection time after 1 / 6H has elapsed, I = I _{t-1 at the first} detection time is compared with the current I = I _t by S7 and S8 to increase or decrease I _t . Determine.

Then, at the time of current equilibrium where I _t = I _{t -1} does not change, the process proceeds from S7 to S9 and Δθ _{t -1 is set} to the previous value, and then t = 2 / 6H is set in S4 to Δθ. Calculate _t . Further, when the current I _t > I _t-1 is increasing, S8 to S1
After shifting to 0 and resetting to t = 0 and setting Δθ _t-1 to the previous value, t = 1 / 6H is set in S4 and Δθ _t-1 is set.
Calculate _t .

When the current is balanced and the current is increased, 1 /
Each time 6H elapses, the process returns to S4 via S9 or S10, and Δθ _t is calculated from the expression of the equation 3.

On the other hand, when the current decreases by I _t <I _t-1 at the second detection time, the process proceeds from S8 to S11 to reset t = 0 and Δθ _t-1 to the previous value, S
According to 12, t = 1 / 6H, and from the formula when the number 6 decreases, Δ
Calculate θ _t . Then, at the third detection time after 1 / 6H has passed, S7, S
To determine the increase or decrease in I _t in the same manner as 8.

When the current is balanced and the current is reduced, S1
5 or S16 through S17 and S19 respectively to S1
Returning to step 2, the Δθ _t is calculated from the equation (6) in S12. Also, when the current increases, S16 through S18
Returning to step 4, the Δθ _t is calculated from the equation (3) by this S4.

On the other hand, the overheat caution temperature θ _L , the overheat judgment temperature θ
_In order to monitor and detect whether or not the temperature reaches _H , the calculation processing unit 16 detects the temperature change amount Δθ in the process of FIG. 6, for example, and detects the temperature θ and the temperature of the conductive unit 3 detected by the temperature sensor 5. Difference from outside temperature θ _a detected by sensor 7 θ _d
Is calculated and this θ _d and θ _L are compared. And θ _d
When ≧ θ _L is reached and the time t ₀ is detected, the process shifts to the comparison between θ _d and θ _H, and the time t _h when θ _d ≧ θ _H is detected.

In order to prevent erroneous detection due to transient fluctuations and the like, the times t _l and t _h are actually detected only when θ _d ≧ θ _L is continuously detected a plurality of times. Then, when the time t _h is detected, the temperature change amount Δθ (= Δθ _nl ) calculated at the times t _l , t _h, and t _h is substituted into the expression of Equation 7, and when the use is continued in this state, The saturation value Δθ _x of the temperature rise is calculated, and this value Δθ _x is substituted into the equation of Equation 8 to calculate the time t _LMT at which the dangerous temperature θ _LMT is reached. further,
The output unit 17 is notified of the occurrence of abnormal overheat and the time t _LMT .

Therefore, based on the measured current of the current transformer 6 and the measured temperature of the temperature sensors 5 and 7, a predictive calculation of the temperature change, a temperature monitoring and a predictive calculation of the time when the dangerous temperature is reached are automatically calculated. The occurrence of abnormal overheat is detected and notified, and the time when the dangerous temperature is reached when the device is continuously used is predicted and notified, so that significant labor saving can be achieved.
Further, the detection accuracy is improved without relying on the experience and intuition of the worker as in the case of the conventional visual inspection.

Further, based on the setting of the sampling cycle, the detection interval of occurrence can be made extremely shorter than in the case of the conventional visual inspection, and the occurrence of sudden abnormal overheating due to a sudden abnormality can be detected and notified early.

Further, since the temperature sensors 5 and 7 and the current transformer 6 may be installed in advance, it is possible to easily detect even a conductive portion that is not easily approached by an obstacle without any inconvenience. The sampling period and constants in each calculation formula may be set according to the usage conditions. Needless to say, a sensor or the like different from the embodiment may be used to detect the temperature of the conductive portion 3, the outside air temperature, and the energizing current. For example, as the temperature sensor 5, a contact output type, a bimetal detection type, a shape memory alloy type. You may use the thing of.

Further, in the case of a conductive part used outdoors, the temperature thereof is also affected by the radiant heat of the sun, so for example the amount of solar radiation is measured to correct the assumed temperature and the reference temperature, and the effect of the radiant heat is taken into consideration. Then, the temperature change amount Δθ may be calculated.

The present invention can be applied to detection of abnormal overheating of conductive parts such as connecting parts of various electric power equipment indoors and outdoors.

[0056]

Since the present invention is configured as described above, it has the following effects. Abnormal overheating occurs and the temperature of the conductive part 3 rises, and the temperature θ _{d obtained} by subtracting the outside air temperature θ _a from the detected temperature θ of the conductive part 3 is the overheat caution temperature θ.
_{When L} and the overheat determination temperature θ _H are reached, the times t _l and t _{h at} which both temperatures θ _L and θ _H are reached are detected. Then, when the overheat determination temperature θ _H is reached, the predicted value of the temperature change amount Δθ based on the detected current at that time and the detected time t.
_l, the saturation value of the rise in the temperature change amount [Delta] [theta] based on the energizing current I from t _h (final value) to calculate the [Delta] [theta] _x, the saturation value [Delta] [theta] _x
The temperature that depends on the energization of the conductive part 3 is
_{Since the} time t _LMT to reach _LMT is calculated and predicted, and the occurrence of abnormal overheating is notified, and the time when it reaches a dangerous state by continuing to use it is notified, It is possible to detect and notify the occurrence of abnormal overheat by a method suitable for automation by predictive calculation based on current and temperature measurement and temperature monitoring without visual inspection of discoloration, and it is possible to predict when dangerous temperature will be reached. It is possible to save labor and improve safety and the like.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a conductive part overheat detection and notification method of the present invention.

FIG. 2 is a schematic diagram of a conductive portion to be detected.

FIG. 3 is a temperature characteristic diagram when an energization current is increased.

FIG. 4 is a temperature characteristic diagram when an energization current is reduced.

FIG. 5 is a temperature characteristic diagram for explaining processing of the arithmetic processing unit.

FIG. 6 is a flowchart for explaining calculation of a temperature change amount.

[Explanation of symbols]

3 Conductive part 5 Conductive part temperature sensor 6 Current transformer 7 Outside air temperature sensor 11 Conductive part overheat detection notification device I Energizing current θ _a Outside air temperature Δθ Temperature change amount θ _L Overheat caution temperature θ _H Overheat judgment temperature θ _LMT Dangerous temperature θ detection temperature

Claims (1)

[Claims] 1. A conducting part, such as a connecting part of a power device, whose temperature exponentially rises due to the occurrence of abnormal overheating, a conduction current, a temperature, and an outside air temperature are periodically detected, and the conduction part is detected from the detected current at each time. The predicted value of the temperature change amount depending on the energization at each time of is calculated, and the temperature obtained by removing the outside air temperature from the detected temperature of the conductive portion at each time becomes a predetermined overheat caution temperature and an overheat determination temperature higher than the temperature. The time to reach is detected, and when the temperature reaches the overheat determination temperature, the saturation temperature of the temperature change amount is calculated from the overheat caution temperature, the time when the overheat determination temperature is reached, and the predicted value. Conductive part overheating characterized by calculating the time at which the temperature that depends on energization reaches the set dangerous temperature from the time function formula of the temperature with a coefficient, and notifying the occurrence of abnormal overheat and the time at which the dangerous temperature is reached. Detection notification method .