JPH09317978A - Abnormality determination method in controlling current-carrying time of electric fusion joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor errors, brought by change with the lapse of time, by applying voltage larger than minute voltage to an electrothermal wire or ID capacitor of a joint, supplying alarm or stopping current-carrying when the difference of the resistance values exceeds allowance. SOLUTION: A capacitance setting means 66 obtains and stores capacitance of electrothermal wire between connector pins. An initial resistance value R1 and a value R2 during current carrying are obtained, and stored. The initial value R1 is compared to the value R2 during current-carrying by means of a comparator 71. Stopping or succeeding of the current-carrying is commanded to a stopping commanding means 72. A raio Z ((R1-R2)/R1) and a temporally changing error allowance S2 are compared to each other by means of the comparator 71. It is determined whether within the range or not. when the wire whose capacitance is independent on temperature is used, it is only determined whether difference is allowable or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion splicing joint (hereinafter referred to as a fusion splicing joint) in which a heating wire is embedded in a joint body made of a thermoplastic resin.
Sometimes it is simply a joint. ) And a thermoplastic resin pipe by electric fusion splicing, the present invention relates to a method for determining an abnormality in energization time control.

[0002]

2. Description of the Related Art It is well known to connect a pipe made of a thermoplastic resin material such as polyethylene or polybutene to a joint by electrofusion. As a method for controlling the energizing time at this time, an electric resistance is obtained by applying an electric current or applying a voltage to the identification resistor (separate from the heating wire) embedded inside the electric fusion joint, and based on this resistance value. The energizing time that has been set in advance according to the type and diameter of the joint (the diameter is the nominal diameter of the connection port and the type is the type of socket, cap, etc.) is determined, and only this time is automatically energized. , So-called resistance identification method for controlling energization time (Japanese Patent Publication No. 3-27014)
There is.

In addition, a bar code in which an energizing time corresponding to each joint is previously input is attached to the joint body itself, and during fusion, a bar code reader or a bar code scanner reads energization control information including the energizing time. The so-called bar code type energization time control method that automatically determines the energization time by
185).

[0004]

By the way, in the electric fusion-bonded joint, the input energy per unit area (KJ / cm2) required for fusion-bonding, so-called fusion-bonding energy, is determined for each joint type and diameter. , This value has been almost established empirically. This fusion energy usually has a permissible width of about ± 20 to 25%. This tolerance range means that errors such as error in resistance of heating wire during energization, correction range of energization time due to environmental temperature difference, output stability on controller side, error in reading resistance value of controller are absorbed. However, as a result, normal fusing performance cannot be obtained.

However, as a practical problem, among the above-mentioned errors in the resistance value of the heating wire during energization, there are variations in the components of the heating wire material, variations in manufacturing due to differences in tension when the heating wire is wound, and the like. In other words, it includes unavoidable errors and time-dependent errors caused by wear and poor contact of the connector. Of these, the time-varying error depends on the situation at the site and how it is used. Therefore, it is not known when and how much it will occur. Conventionally, there has been no means for monitoring the error that changes with time, and as a result, there is a problem that the error deviates from the above-mentioned permissible range and defective fusion occurs.

Among the above-mentioned conventional techniques, the former method determines the energization time t based on the resistance value R obtained by measuring the voltage or current, and the fusion energy En is the resistance value. R and energization time t are doubly related.
For example, in the case of constant current control, E _n = I ² Rt, and the resistance value R and the energization time t are in a proportional relationship. On the other hand, in the case of constant voltage control, En = V ² t / R, and the resistance value R and the energization time t are in inverse proportion. Here, paying attention to the error of the resistance value of the heating wire, that is, the above-mentioned unavoidable error, if the obtained resistance value R has an error, the energization time t determined based on this resistance value R is also the same. The error will be included. After all, this error is due to the fusion energy E in constant current control.
It influences n in proportion to the square, and in constant voltage control, it influences in inverse proportion to the square. as a result,
There is a problem that the margin of the allowable width of other errors is lost only by the resistance error of the heating wire.

On the other hand, in the latter method, since the energization time is determined in advance by bar-coding, the fusion energy E
The influence on n is only the error of the resistance value R of the heating wire during energization, and the influence on the total allowable width is less than that of the above method. However, since the data itself entered in the barcode also contains an error, the result is equivalent to the former method. From the above, an unavoidable error will occur in any case, so the other time-dependent error should be eliminated as much as possible, or this abnormality (contact failure) should be checked during energization. It can be said that such abnormality determining means is necessary.

In view of the above, the present invention monitors a time-dependent error mainly due to wear or loss of the connector pin portion, poor contact, etc., and keeps this error within the allowable error range that affects fusion energy. An object of the present invention is to provide a method for determining an abnormality in controlling the energization time of an electric fusion joint so that normal fusion splicing can always be obtained.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a weak voltage is applied to a heating wire or an identification resistor of a joint to be fused in controlling the conduction time of an electric fusion joint in which the conduction time is set. To obtain the electric resistance value R1 and then
A voltage larger than the weak voltage is applied to the heating wire or the identification resistor of the joint to obtain an electric resistance value R2, and the R
When the difference between 1 and the value R2 is within the predetermined allowable amount, energization is continued, and when the difference between the value R1 and the value R2 is outside the predetermined allowable amount, an alarm is issued and / or the energization is stopped. It is a method for determining an abnormality in controlling the energization time of an electric fusion joint.

At this time, the above-mentioned energization time may be set by obtaining the electric resistance value of the heating wire or the identification resistor provided in the electric fusion joint and setting it based on this electric resistance value. Alternatively, the bar code may be attached to the electric fusion joint and set by reading a bar code in which energization control information is input in advance.

Further, according to the present invention, the electric resistance value of the heating wire of the joint or the identification resistor is input in the control information of the bar code, which is set as the electric resistance value R1 ', and then the electric resistance value R1' is set. A predetermined voltage is applied to the heating wire or the identification resistor of the joint to obtain the electric resistance value R2, and the value R
When the difference between 1'and the value R2 is within the predetermined allowable amount, energization is continued, and when the difference between the value R1 'and the value R2 is outside the predetermined allowable amount, an alarm is issued and / or the energization is stopped. Is a method for determining an abnormality in controlling the energization time of the electric fusion joint.

The difference between the electric resistance value R1 or R1 'and the electric resistance value R2 is the ratio of the electric resistance values represented by (R1-R2) / R1 or (R1'-R2) / R1' The allowable amount S2 is −12% to −3% ≦ S2
It is desirable to be ≦ + 3% to + 12%. The above-mentioned weak voltage is several mV to several tens of mV (millivolt), and a voltage higher than this and a predetermined voltage to be applied thereafter need to be 10 times or more of the weak voltage, for example, during fusion. Corresponds to the applied voltage of. When setting the energization time, it is desirable to measure the ambient temperature and correct the energization time or the fusion energy according to this temperature.

Further, according to the present invention, the non-energized state can be determined by monitoring whether or not the heating wire of the joint is energized, that is, by monitoring the loop current, voltage value or current value in the joint including the connector contact portion. When it occurs, it is counted, and when this non-energized state recovers within a predetermined time, the interrupted time is added to continue energizing, and the count number of the non-energized state becomes a predetermined value. In this case, the control includes stopping the energization. At this time, the non-energized state is 1
If it continues for more than 2 seconds continuously, a disconnection error is displayed and
When the count of the non-energized state is repeated twice or more, it is desirable to display a connector abnormality and stop energizing each.

As described above, according to the present invention, first, a weak voltage of several mV to several tens of mV (millivolt, the same applies hereinafter) is applied to measure the current, and the electric resistance value R1 is obtained, which is embedded in the joint. The resistance value of the heating wire itself may be used, or the resistance value of the identification resistor provided separately from the heating wire as in the conventional example may be used. In any case, this becomes the reference resistance value for checking. Further, since the voltage is weak, the joint is not heated by this, and there is no influence on the subsequent fusion work. After that, 10 is lower than the weak voltage.
Since it is difficult to reliably detect changes unless the voltage is at least twice as high, or at least 10 times or more, for example, in the case of a heating wire, the fusion voltage after the start of energization may be sufficient, and in the case of an identification resistor, it may be several 100 mV before the start of energization. There will be. These are energized, the electric resistance value R2 is obtained again, and this is used as a comparison target.

Then, the electrical resistance value R1 before starting the fusion and the electrical resistance value R2 during the fusion are compared, and for example, it is checked whether or not the ratio of these values is within a predetermined range. This also means monitoring whether or not an abnormality has occurred in the connector portion or the like. In other words, for example, when the spring force of the connector terminal on the concave side of the connector is deteriorated and the fitting is loose, or the part on the convex side of the pin is worn or missing, contact failure etc. As a result, a change occurs between the values R1 and R2, and this change is taken out as a time-dependent error, and as a result, the presence or absence of abnormality in the connector section is monitored.

Here, as shown in FIG. 1, the permissible width S of the fusion energy is 2 evenly in the vertical direction with the environmental temperature as the horizontal axis.
A width of about 0 to 25% (hereinafter, 22.5%) is provided. Various factors included in the fluctuation of the permissible width include a variation error of the heating wire material of ± 3%, a variation error of the joint manufacturing of ± 2%, (the total of these two errors of ± 5% is a Next, the measurement error due to ambient temperature is ± 1%, the reading error on the controller side is ± 3%, the output error of the controller is ± 2%, and the total error of ± 6% is due to the accuracy of the equipment. The above ± 5% and ± 6% errors are included in the unavoidable error S1. Therefore, the remaining S2 is a width given to the error which changes with time, that is, corresponds to the above-mentioned predetermined allowable amount.

In the former method in which the resistance value of the heating wire or the discriminating resistor is obtained and the energization time is determined based on the resistance value of the allowable amount S2, the above ± 5% can be obtained by squaring as described above. Therefore, it will be about ± 10%. Therefore, S2
The range of is 2.5%, which is obtained by subtracting 10% and 6% from 22.5%. On the other hand, S2 of the bar code method is 11.5%, which is the value obtained by subtracting 5% and 6% from 22.5%, but the error between the resistance value originally input to the bar code and the actual heating wire resistance value. Since it is necessary to see ± 3%,
It becomes 8.5% after subtracting this. In the present invention, both are put together, and this is set to -12% to -3% with a margin between the upper and lower sides.
≦ S2 ≦ + 3% to + 12%. The above-mentioned numerical values are converted into fusion energy and are approximate values.

Further, since the non-energization time may sometimes occur during the actual fusing work, it is possible to monitor the presence or absence of abnormality of the connector portion by counting such a state. For example, when the loop current in the joint is monitored and the non-energized state is repeated intermittently, it is considered that the connector portion has a poor contact and an alarm is displayed. Further, when the non-energized state continues for a considerable time, it is regarded as a disconnection abnormality and an alarm is displayed to enhance the monitoring function. On the other hand, in the case of the return, the amount of the interrupted time is added to make the total fusion energy equal so that the normal fusion is corrected.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. First, in the present embodiment, a constant current control controller is used, and the relationship between the electrical resistance value R of the heating wire of the electric fusion joint and the energization time t (R-t diagram) rises to the right and uniformly increases monotonously. The electric conduction time t is uniquely set for the electric resistance value R obtained by measuring the current or the voltage, which is set as
An energization time control method in which is determined will be described as an example.

For example, the solid line in FIG. 2 indicates the nominal diameter of the socket of 10 mm (S10), 13 mm (S13) and 16 mm (S).
16) the relationship between the electrical resistance value R and the energization time t, and the relationship between the electrical resistance value R and the energization time t of the different diameter socket with nominal diameters of 13 × 10 mm (RS13 × 10) and 16 × 13 mm (RS16 × 13) Shows. The joint is set by manipulating the length and thickness of the heating wire or the material so as to have such a relationship. In actual control, these are converted into a straight line represented by t = 20R-10, and the R-t diagram shown in FIG. 3 is set and stored. According to this energization time control, there is no need to individually identify the product size, and the energization time t corresponding to the electrical resistance value R of each electric fusion joint is given one to one. For example, when the electric resistance R measured in S13 is 1.84Ω, the energization time t is 26.
8 seconds is automatically given, RS13 × 10 electric resistance R
Is 1.89Ω, the energization time t is automatically given as 27.8 seconds. As a result, the optimum fusion energy set for each product diameter is given to each.

In the process of performing this energization time control, the presence or absence of the above-mentioned abnormality is determined. This will be described with reference to the flowchart shown in FIG. The numbers represent step numbers, and in this example, the energization time is corrected by the ambient temperature. (1) Turn on the controller power. At the same time, check the input voltage, frequency and leakage. (2) Along with the above checks, or after that, the ambient temperature is detected by the temperature sensor. (3) Next, connect the controller terminals to the connector pins of the joint. (4) Applying a weak voltage of several tens of mV to both ends of the connector pin and measuring the current, the electrical resistance value R of the heating wire itself
Ask for 1. (5) This electric resistance value R1 and the preset R-t
The energization time t1 is set by comparing with a line diagram (stored in the microcomputer). (6) After the energization time t1 is set, or simultaneously with the setting, the energization time t2 is set by adding the correction according to the environmental temperature. The energization time t2 is obtained by the following equation, for example. t
2 = t1 × {1− (environmental temperature−23 ° C.) × temperature correction coefficient} The temperature correction coefficient is preferably about 0.006 to 0.01, and 0.008.
Is more preferred. Actually, it is not necessary to set the energization time t1 if t2 is simultaneously calculated by the above equation. When the correction based on the environmental temperature is not added, it may be executed at time t1.

(7) Turn on the fusion start button. It should be noted that the resistance value of the heating wire is continuously monitored until the button is turned on, and when the variation of the resistance value is 0.5Ω or more, it is regarded as abnormal and cannot be turned on. (8) Apply the fusion voltage, and then relatively early (5
Within about a second), take the voltage between the connector pins again,
The electric resistance value R2 of the heating wire at this time is obtained. In this example, the fusion voltage is measured to obtain the resistance value, but this may be another voltage value that is 10 times or more the weak voltage. (9) From the initial resistance value R1 and the resistance value R2 at the time of fusion (R1
The ratio Z% of -R2) / R1 is calculated. Further, the permissible amount S2 of an error with time due to poor contact of the connector pin or the like is set to ± 5% (± 0.05). It should be noted that the allowable amount can be separately set to an arbitrary value. (10) Compare Z and S2. When Z ≧ S2, an alarm signal is output as a connector abnormality, and for example, a buzzer sounds in a continuous tone, and appropriate subsequent measures are taken. Alternatively, stop energizing with the buzzer.

(11) When Z ≦ S2, energization is continued. (12) Whether or not the heating wire is energized is monitored by constantly monitoring the loop current in the joint between the connectors, and when a de-energized state occurs, it is counted. Here, the presence or absence of energization does not mean whether or not there is an output from the controller, but refers to whether or not the connector connection between the heating wire of the joint and the controller side is normal with a closed circuit maintained. (13) Monitor whether the non-energized state returns within 1 second. If it does not recover after 1 second or more, an alarm message indicating a disconnection error will be displayed and the power supply will be stopped. (14) If the power is recovered within 1 second, the interrupted time is added to the energization time t2 to continue energization. (15) If the number of counts in the non-energized state reaches 2, an alarm is displayed for a connector error and the energization is stopped. (16) The energization is stopped when the energization time t2 (or t1) has elapsed. And the buzzer of fusion completion is sounded with an intermittent sound.

Next, the electric fusion controller will be further described. The controller of the embodiment described below,
Current 5.5A inside the controller from input power AC100V
(Variable) constant current control system converted to constant current control method, energizing time control as described above for heating wire resistance value R for each joint
Is read, the temperature is added to this, and the energization time t (t
2) is set. FIG. 5 is a block diagram of the controller of the embodiment. Here, the fusion power source unit 63 converts the current into a constant current power source of 5.5 A through a breaker 61 and a relay 62 in the controller 60. After that, the connector 66 can be connected to the connector pin on the joint side via the relay 64.

Next, there is provided a resistance value setting means 66 for finding and storing the electric resistance value of the heating wire between the connector pins, where the initial resistance value R1 and the resistance value R2 during energization are found and stored. The initial resistance value R1 is sent to the R-t diagram storage unit 67 that stores a predetermined R-t diagram in advance, and the energization time t1 corresponding to the resistance value R1 is set by the energization time setting means 68. On the other hand, it has a temperature sensor 70 such as a thermistor for measuring the ambient environment temperature and a corrected energization time t2 setting means 69 for compensating the energization time based on this environment temperature.
Note that the energization time t2 is set at the same time without setting t1 here.
The energization time setting means 68, 6
9 may be together. Also, in the case of using barcodes, a barcode reader etc. is provided separately from the connector,
The R-t storage unit 67 (when the resistance value is set) or the t1 setting means 68 (when the energization time is set) is contacted via the barcode detection unit.

Further, it has a comparison means 71 for comparing the resistance value R1 initially obtained with the resistance value R2 obtained during energization, and a continuation stop instruction means 72 for giving an instruction to stop or continue energization according to the comparison result. ing. The comparison means may compare the ratio Z with the allowable amount S2 and determine whether this is within or outside the range. For example, when a heating wire whose resistance value does not depend on temperature is used, the difference is simply within the allowable amount. It may be determined whether or not. And, each of the above-mentioned means and others are the same as the microcomputer CP.
It is placed in U77 and controlled. Also,
An energization start command means 73 for instructing the start of energization is turned on / off by a fusion start button attached to the upper surface of the main body, and an emergency stop button is additionally provided on this surface.

The external display (LCD) unit 75 displays the energization time (countdown), size display and input voltage abnormality, output current abnormality, heating wire short circuit (this occurs during the energization period,
The resistance value is constantly monitored, and when the resistance value changes by 7% or more, it is regarded as abnormal. ), Connector dropout, overheat, and abnormal environmental temperature (-10 ° C or lower or 40 ° C or higher) are detected and displayed. Reference numeral 74 is a buzzer which outputs audio in conjunction with the alarm display and the power supply stop command, or when fusion is completed. Further, the above-mentioned alarm can control ON / OFF of the fusion power source and the relay, and is linked with the stop of energization. Reference numeral 76 denotes a control power source and an accessory power source unit. The control power source is, for example, an analog power source a, a CPU power source b, a relay power source c, and an accessory tool power source d.

The above-described embodiment is directed to a method of extracting and identifying the resistance value of the heating wire of the joint, but this is identified based on the resistance value of the identification resistor provided separately from the heating wire. Even if the method is replaced as a target, the method can be similarly performed based on the control information therein by using a barcode. Further, the controller may be implemented by a constant voltage control method using a constant voltage controller instead of the constant current control method using a constant current type controller. However, in the case of constant voltage control, as described above, En = V ² t / R is expressed, and in addition to the unavoidable error caused by the resistance value R of the heating wire, the phenomenon of poor contact of the connector part Directly affects the voltage V in the above equation and affects En. Therefore, as described below, the resistance value R1 ′ input to the bar code and the resistance value R1 ″ obtained by actually applying the weak voltage are first compared to check whether or not this is within the allowable amount. This is an effective means for detecting poor contact.

Next, an embodiment using a bar code in which control information and the like are input in advance will be described. The barcode is
Using a 24-digit or 32-digit barcode, the information is, for example, as shown in FIG. 6, information such as A ... manufacturer name, B ... joint type, C ... joint caliber size, D ... serial number, E ... Resin material, F ... Current value (for constant current control) or voltage value (for constant voltage control), G
... Resistance value of heating wire of joint or resistance value of identification resistor,
H ... fusion energy (En) or energization time (t),
Are entered. Here, when a wire having a resistance temperature coefficient is used as the heating wire 2, it is desirable to add I ... Resistance temperature coefficient and correction by the ambient temperature, so that J ... Temperature correction coefficient can be input respectively. good. Then, the above bar code is attached to each joint by sticking it on the joint body. This bar code type energization control is performed by directly using the fusion energy or the energization time previously input to the H code.
Therefore, in the resistance identification type joint provided with the identification low antibody,
The meaning of this discriminating low antibody is used for carrying out the abnormality discrimination in the present invention.

Regarding the method of determining the abnormality of the connector part,
This can be performed in the same manner as the flow of FIG. 4 described above. As another embodiment, the resistance value in the G code of the bar code is directly regarded as the electric resistance value R1 ', and then a predetermined current is passed through the heating wire or the discriminating resistor of the joint to obtain the electric resistance value R2. , And the same as above for the electric resistance value R1 ′
And the electrical resistance value R2, for example (R1'-R2) / R
When the ratio Z ′ of 1 ′ is within the predetermined allowable amount S2, energization is continued, and when Z ′ is outside the predetermined allowable amount S2, the alarm and the energization are stopped. I can. Also, prior to the above abnormality determination check,
The resistance value R1 ″ obtained by applying a weak voltage or a predetermined voltage to the heating wire of the joint is compared with the resistance value R1 ′ of the bar code (or determined in correspondence with these resistance values R ″ and R ′). If the difference exceeds the allowable amount (for example, 5% or more), an alarm may be generated and an alarm may be generated. It is possible to check the presence or absence, and it is possible to call out an abnormality such as the heating wire of the fitting being improper, the wrong bar code being stuck, or the bar code being dirty in some cases.

In addition, in the case of the example using the bar code as described above, the control is relatively simple, and various data such as the manufacturer name, the manufacturing number, and the resin material are also input to the bar code. Therefore, these data can be stored together in the controller during the fusing operation. Therefore, when a problem occurs later, it is easy to carry out a follow-up investigation of when and under what fusion condition this joint was used, which is useful for early problem solving.

[0032]

As described above, according to the present invention, it is possible to monitor temporally varying errors, which are mainly caused by wear or loss of the connector pin portion, contact failure, and the like. At the same time, by keeping this error within the allowable range of the fusion energy, a normal fusion connection can always be obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a fusion energy and an allowable amount.

FIG. 2 is an R-t diagram showing a relationship between an electric resistance R and an energization time t for explaining an embodiment of an energization time control method.

3 is a diagram in which the vertical and horizontal axes of the R-t diagram in FIG. 2 are converted.

FIG. 4 is a flowchart showing an abnormality determination method in energization time control according to an embodiment of the present invention.

FIG. 5 is a block diagram showing an embodiment of an electric fusion controller.

FIG. 6 is a schematic diagram illustrating an example of code data of a barcode.

[Explanation of symbols]

60 Electric fusion controller 66, 69
Resistance value setting means 67 R-t diagram storage section 68 Energization time setting means 70 Temperature sensor 71 Comparison means 72 Energization stop command means 73 Energization start means 74 Alarm means (buzzer) 75 External display section

Claims (8)

[Claims] 1. In controlling the energization time of an electric fusion joint in which the energization time is set, first, a weak voltage is applied to the heating wire or the identification resistor of the joint to be fused so that the electric resistance value R1 is set. Then, a voltage larger than the weak voltage is applied to the heating wire or the identification resistor of the joint to obtain the electric resistance value R2. When the difference between the value R1 and the value R2 is within a predetermined allowable amount, A method for determining an abnormality in energization time control of an electric fusion joint, wherein energization is continued and an alarm is issued and / or energization is stopped when a difference between the value R1 and the value R2 is outside a predetermined allowable amount. 2. The setting of the energization time is performed by obtaining an electric resistance value of a heating wire or an identification resistor provided in the electric fusion joint,
The abnormality determining method in the energization time control of the electric fusion splicing joint according to claim 1, wherein the abnormality is set based on the electric resistance value. 3. The setting of the energization time is performed by reading a bar code which is attached to an electric fusion joint and in which information of energization control is input in advance. A method for determining abnormality in controlling the energization time of an electric fusion joint. 4. The energization time control of the electric fusion joint, wherein the energization time is set by reading the bar code which is attached to the electric fusion joint and in which the information of the energization control is input in advance. In the control information, the electric resistance value of the heating wire of the joint or the identification resistor is input, and this is taken as the electric resistance value R1 ′, and then the predetermined voltage is applied to the heating wire of the joint or the identification resistor. When the difference between the value R1 ′ and the value R2 is within a predetermined allowable amount, energization is continued, and the difference between the value R1 ′ and the value R2 is outside the predetermined allowable amount. In this case, a method of determining an abnormality in controlling the energization time of the electric fusion joint is characterized by issuing an alarm and / or stopping energization. 5. The difference between the electric resistance value R1 or R1 ′ and the electric resistance value R2 is defined as a ratio of electric resistance values represented by (R1−R2) / R1 or (R1′−R2) / R1 ′, Allowable amount S2 is −12% to −3% ≦ S2
≦ + 3% to + 12%, The method for determining an abnormality in controlling the energization time of an electric fusion joint according to any one of claims 1 to 4. 6. The electric fusion according to claim 1, wherein the voltage higher than the weak voltage or the predetermined voltage is a value which is 10 times or more the weak voltage. Abnormality discrimination method in joint energization time control. 7. The heating wire of the joint is monitored for the presence or absence of energization, and when a non-energized state is generated, it is counted, and when the non-energized state is recovered within a predetermined time, the interrupted time is determined. The energization time of the electric fusion joint according to any one of claims 1 to 6, wherein energization is continued by adding, and energization is stopped when the count number in the non-energized state reaches a predetermined value. Abnormality determination method in control. 8. A disconnection abnormality is displayed when the non-energized state continues for one second or more continuously, and a connector abnormality is displayed when the non-energized state is counted twice or more. The method for determining an abnormality in energization control of an electric fusion joint according to claim 7, wherein the energization is stopped.