JP2000298153A - Device and method for checking soundness of connection of cable terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for checking the soundness of the connections of cable terminals, whereby even slight changes in resistance of terminal portions caused by oxidation of the connections, insufficient clamping torque and the like can be surely detected. SOLUTION: Three phases on the load sides of cable terminal portions 7U, 7V, 7W which connect a power supply side cable 8 electrically to a load side cable 12 are shorted by means of a cable 5 for three-phase short circuits, and rated currents are passed from the power supply sides of the cable terminal portions 7U, 7V, 7W. The values of currents flowing in the cable terminal portions 7U, 7V, 7W and voltage values are measured with a measuring device 10 and Joule's heat is computed from the measured values. The computation result is compared with an allowable value to determine whether or not the connections of cable terminals are sound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a checking device and a checking method for checking the soundness of a connection portion of a cable terminal of an electric device through which a large current flows, such as a motor or a transformer.

[0002]

2. Description of the Related Art In a terminal connection portion of an electric device through which a large current flows, the electrical resistance of the terminal portion increases due to oxidation of a contact surface of the terminal portion and insufficient tightening, which may cause an abnormality due to heat generation of the terminal portion. There is. Particularly, in a device that handles a large current, a large increase in heat is generated even by a slight increase in contact resistance. Therefore, it has been desired to detect an abnormality as early as possible.

[0003] Japanese Patent Application Laid-Open No. 8-11463 discloses an apparatus which can automate the operation of measuring the contact resistance value at the contact portion of a conductor, eliminate human measurement errors, and measure the contact resistance value with high reliability.
No. 4 discloses this.

[0004] Regarding the oxidation of the cable terminal portion, a method of confirming the soundness by visual observation or resistance measurement has been performed.
Regarding insufficient tightening of the terminal, a method of confirming soundness by measuring a torque value of a tightened portion has been performed.

[0005]

In the visual method, it is difficult to judge the soundness unless oxidation progresses considerably. In the method based on the resistance value measurement, the resistance value increases due to an initial abnormality or the like. Could not be determined when was small. The method based on the torque measurement has a problem that even when an oxide film is generated in the contact portion, even in a case where the tightening torque is sufficient, it is often in an abnormal state and cannot be detected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for confirming the soundness of a connection portion of a cable terminal which can reliably detect even a slight change in the resistance of the terminal portion due to oxidation of the connection portion and insufficient tightening torque. Is to provide.

[0007]

Means for Solving the Problems In order to achieve the above object, a feature of the apparatus for confirming the soundness of a connection portion of a cable terminal according to the present invention is that a terminal of a cable terminal for electrically connecting a cable to a cable is provided. After short-circuiting the load side of the section, an inspection current is passed from the power supply side of the terminal section, Joule heat is calculated from the measured value of the current flowing through the terminal section and the voltage, and the calculated result is compared with an allowable value. It is to determine the soundness of the connection part of the cable terminal.

Specifically, the present invention provides the following apparatus and method. The present invention relates to a cable terminal connection part soundness checking device for checking the soundness of a cable terminal connection part for electrically connecting a cable to a cable, wherein the three phases on the load side of the cable terminal part are short-circuited. A short-circuit cable to be connected, a constant current supply source for supplying an inspection current corresponding to a rated load current value from a power supply side of the terminal portion, a current measuring device for actually measuring a current value flowing through the terminal portion, and a voltage applied to the terminal portion. A voltage measuring device for actually measuring a voltage value to be measured, calculating Joule heat from the actually measured current value and voltage value, and comparing the calculated result with a preset allowable value to determine the soundness of the connection portion of the cable terminal. And a computer for determining the soundness of the cable terminal.

The present invention also relates to a method for confirming the soundness of a connection part of a cable terminal for confirming the soundness of a connection part of a cable terminal for electrically connecting a cable to a cable. Short-circuit the three phases, a test current corresponding to a rated load current value flows from the power supply side of the terminal section, and a current value flowing through the terminal section and a voltage value applied to the terminal section are measured, and Calculating the Joule heat from the actually measured current value and voltage value, and comparing the calculated result with a preset allowable value to determine the soundness of the connection part of the cable terminal; Provides a method of confirming the soundness of the department.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an apparatus and method for checking the integrity of a cable terminal connection according to an embodiment of the present invention.

FIG. 1 is a conceptual diagram showing a configuration of a cable terminal connection part soundness checking apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of the measuring device of FIG.

Cable terminal portions 7U, 7V, 7W for confirming soundness are housed in the terminal box 1. Each cable terminal portion electrically connects the power supply side cable 8 and the load side cable 12 to each other. ing.

The load side cable 12 of each cable terminal portion
Is connected to a load such as a motor or a transformer, and the power supply side cable 8 is connected to the electric equipment 2 on the power supply side.

Normally, a load current flows from the power supply side device 2 via the power supply side cable 8, the cable terminals 7 U, 7 V, 7 W, and the load side cable 12.

In order to inspect the soundness of the cable terminals 7U, 7V, 7W, first, a breaker (not shown) on the power supply side is opened, and the constant current source 3 is connected to the power supply side cable 8. I do.

The constant current source 3 includes a three-phase transformer 13 and a three-phase induction voltage regulator 14, and supplies a test current corresponding to a rated load current. At the time of the soundness inspection, the voltage applied to the constant current source 3 is lower than the voltage during normal operation because the load-side cable 12 is short-circuited as described later.

The load sides of the cable terminals 7U, 7V, 7W are short-circuited by three-phase using a three-phase short-circuit cable 5. In order to detect a test current flowing through each phase, a clamp-type current transformer 11 is attached to each phase of the power supply side cable 8. Furthermore,
In order to measure the voltage applied to each of the cable terminal portions 7U, 7V, 7W, the clip 9 between the cable connection terminals is attached.

The clamp type current transformer 11 and the clip 9 between the cable connection terminals are connected to the measuring device 10.
The voltage value applied to each cable terminal portion is actually measured by a voltage measuring device 110a within 0, and the current value flowing through each cable terminal portion is actually measured by a current measuring device 110b.

Further, a thermistor 6 is connected to each cable terminal.
Is attached, and the terminal temperature measuring device 110c in the measuring device 10 is attached.
Measure the temperature at the time of inspection.

As shown in FIG. 1, the measuring device 10 is set, and an inspection current is supplied from the constant current source 3 for a predetermined time, for example, 1 minute.
The current value and the voltage value of each cable terminal are measured for 0 minute, and the Joule heat generated in each cable terminal is calculated by the calculator 130 from these measured values by the calculator 130.
Compare the calculation result with a preset allowable value. If the calculation result is less than the allowable value, the connection of each cable terminal is determined to be sound (good connection). ) Is determined.

The judgment result is displayed, for example, by a pass / fail judgment indicator light 15 and printed out from the printer 150.

Further, by measuring the temperature of the connection portion of each cable terminal portion with the terminal temperature measuring device 110c via the thermistor 6, the validity of the resistance value with respect to the temperature change of each cable terminal portion can be confirmed.

FIG. 3 is a circuit diagram of the measuring apparatus 10 of FIG. The current and voltage signals for each phase are
Multiplier 1 via amplifiers 120U, 120V, 120W
31U, 131V and 131W, where the power consumption P is calculated. Power consumption P calculated by each multiplier
Together with the signal from the timer 135,
132V, 132W.

The timer 135 is used to set the measurement time of the voltage and the current, and is set to 10 minutes in this embodiment. Switch 135a of timer 135
Is activated at the start and end of the measurement time,
The measurement time is input to U, 132V, and 132W.

Each computing unit computes the generated Joule heat from the input power consumption and the measurement time, and determines the computed value as a decision unit 140
Output to The determiner 140 corrects the permissible value from the setting device 145 based on the temperature measurement value of the connection portion of each cable terminal portion taken from the terminal temperature measuring device 110c, and corrects the permissible value and the input calculated value. Are compared with each other, and the soundness of the connection portion of the cable terminal portion is determined for each phase based on the criteria described above.

The result of the judgment is displayed on the pass / fail judgment indicator light 15, and detailed data is printed out from the printer 150.

The present invention has the following functions and effects by adopting the structure of the above embodiment.

1) Oxidation of the connection portion of the cable terminal and a slight change in the resistance of the terminal portion due to insufficient tightening torque can be reliably detected, and the soundness of the connection portion of the cable terminal can be easily confirmed. Can be.

2) The inspection current at the time of checking the soundness of the connection portion of the cable terminal is large, but the applied voltage is low, so that there is no danger of electric shock or the like during the measurement work.

3) By measuring the temperature of the connection portion of the cable terminal, the validity of the resistance value with respect to the temperature change can be confirmed.

4) By using the rated current supply source and the measuring instrument, it is possible to easily calculate the Joule heat and check the soundness of the connection of the cable terminals.

[0032]

According to the present invention, it is possible to reliably detect even a slight change in the resistance of the terminal portion due to oxidation of the connection portion of the cable terminal and insufficient tightening torque, thereby reducing connection failure. Thus, the reliability of the cable terminal connection can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the configuration of a cable terminal connection part soundness checking device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the measuring device of FIG.

FIG. 3 is a circuit diagram of the measuring device of FIG. 1;

[Explanation of symbols]

1: Terminal box, 3: Constant current source, 5: Three-phase short-circuit cable,
6 ... Thermistor, 7U, 7V, 7W ... Cable terminal part, 8 ... Power supply side cable, 9 ... Clip between cable connection terminals, 10 ... Measuring device, 11 ... Clamp type current transformer, 12
... Load side cable, 15 ... Good / bad judgment indicator light, 110a ...
Voltage measuring device 110b Current measuring device 110c Terminal temperature measuring device 130 Calculator 131 Multiplier 132
Arithmetic unit, 140: judgment unit, 150: printer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mineo Takagi 3-2-2, Sachimachi, Hitachi-shi, Ibaraki Prefecture Within Hitachi Engineering Services Co., Ltd. (72) Inventor Hiroshi Koyamauchi 3-chome, Sachimachi, Hitachi-shi, Ibaraki Prefecture No. 2 F term in Hitachi Engineering Services, Ltd. (reference) 2G014 AA01 AA14 AA34 AB33 AB43 AC08

Claims (2)

[Claims] An apparatus for confirming soundness of a connection part of a cable terminal for confirming soundness of a connection part of a cable terminal for electrically connecting a cable to a cable, comprising: A short-circuit cable to be short-circuited, a constant current supply source for supplying an inspection current corresponding to a rated load current value from a power supply side of the terminal portion, a current measuring device for actually measuring a current value flowing through the terminal portion, A voltage measuring device for measuring the applied voltage value, and calculating the Joule heat from the actually measured current value and voltage value, comparing the calculated result with a preset allowable value, and connecting the cable terminal. A connection terminal soundness confirmation device for a cable terminal, comprising: a computer for determining soundness. 2. A method for confirming soundness of a connection portion of a cable terminal for confirming soundness of a connection portion of a cable terminal for electrically connecting cables to each other, comprising: Short-circuit,
A test current corresponding to a rated load current value is passed from the power supply side of the terminal portion, a current value flowing through the terminal portion and a voltage value applied to the terminal portion are actually measured, and from the actually measured current value and voltage value, A method for confirming the soundness of a connection portion of a cable terminal, comprising calculating a Joule heat and comparing the calculation result with a preset allowable value to determine the soundness of the connection portion of the cable terminal.