CN112034235A - Device and method suitable for measuring power frequency voltage of T-shaped cable connector - Google Patents

Abstract

The invention relates to a device and method suitable for measuring the power frequency voltage of a cable T-joint. The measuring device includes: a plug measuring module and a voltage determining module; the plug measuring module includes a measuring resistance and a metal cavity; a metal block is cut on the inner cavity of the metal cavity, and the metal block is pasted at the cutting position to serve as a metal Sensing sheet; the voltage determination module is used to determine the power frequency voltage of the cable joint according to the voltage signal at both ends of the measuring resistor. The measuring device and method provided by the present invention can determine the power frequency voltage of the measured cable joint in real time by acquiring the voltage signal of the measuring resistance, thereby solving the problem in the prior art that it needs to consume a lot of manpower and material resources and cannot be found in time. Problem with defective cable glands.

Description

A device and method suitable for power frequency voltage measurement of cable T-joint

technical field

The invention relates to the technical field of power frequency voltage measurement, in particular to a device and method suitable for power frequency voltage measurement of a cable T-joint.

Background technique

With the vigorous development of my country's power construction, the high and low voltage lines of urban, industrial and mining and national defense construction have gradually been cabled, and the growth of power cable lines has been very rapid. Therefore, it is an important task to ensure the safe operation of the power cable, troubleshoot timely and correctly, and restore the power supply quickly. As a terminal device, the cable joint is connected between the cable and the electrical isolation layer of the transformer, switch and other equipment, and is an important part of the power cable. At the same time, because the metal sheath of the body is peeled off at the cable break, the electric field distribution inside the cable T-head becomes very complicated, and breakdown faults occur from time to time, which has caused great damage to the safe and stable operation of the power cable. influences. Then it is necessary to accurately measure the running state of the cable joint, find the cable joint in poor running state in time, and deal with it.

There is currently no automated technology that enables accurate voltage measurement of cable joints. In the existing engineering measurement process, the detection of the running state of the cable joint still uses manual timing and fixed-point measurement.

Therefore, the measurement method in the prior art not only consumes a lot of manpower and material resources, but also cannot find the defective cable joint in time.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device and method suitable for measuring the power frequency voltage of a cable T-joint, so that the cable joint can be measured timely and accurately while saving manpower and material resources.

For achieving the above object, the present invention provides the following scheme:

A device suitable for power frequency voltage measurement of a cable T-joint, comprising: a plug measurement module and a voltage determination module;

The plug measurement module is installed at one end of the cable joint; the plug measurement module includes a measurement resistance and a metal cavity;

A metal block is cut on the inner cavity of the metal cavity, and the metal block is pasted at the cutting position to serve as a metal sensing piece; the measuring resistor is placed in the metal cavity, and the measurement One end of the resistor is connected to the metal cavity wall, and the other end of the measurement resistor is connected to the metal sensor sheet; the voltage determination module is connected to the measurement resistor, and the voltage determination module is used to measure the resistance according to the measurement resistor. The voltage signals at both ends determine the power frequency voltage of the cable joint.

Preferably, the plug measuring module further comprises: a plug insulating layer and a plug conductive layer;

The plug conductive layer is clamped at one end of the cable conductor; the plug insulation layer is the filling body of the plug measurement module, which is used to wrap the plug conductive layer and the metal cavity.

Preferably, the plug measuring module further comprises a plug installation hole;

The plug installation hole penetrates through the plug insulation layer and the metal cavity, and the plug installation hole is located on a cavity of the metal cavity opposite to the metal induction sheet.

Preferably, the measuring device further includes a coaxial cable;

The coaxial cable passes through the plug mounting hole, one end of the coaxial cable is connected to both ends of the measuring resistor, and the other end of the coaxial cable is connected to the voltage determination module.

Preferably, the material of the plug conductive layer and the material of the metal cavity are both conductive metal materials.

Preferably, the plug measuring module further includes an insulating film;

The insulating film is attached to the sidewall of the metal induction sheet.

Preferably, the measurement resistance is a resistance with a resistance value of 2kΩ-10MΩ.

Preferably, the voltage determination module includes: a voltage calculation unit and a display unit;

The voltage calculation unit is respectively connected with the measurement resistor and the display unit; the voltage calculation unit is used to determine the power frequency voltage according to the voltage signal at both ends of the measurement resistor; the display unit is used to display the power frequency voltage.

Preferably, the thickness of the cavity of the metal cavity is 2-4 mm.

A method suitable for power frequency voltage measurement of a cable T-joint, comprising:

An equivalent circuit model is constructed according to the above-mentioned device suitable for power frequency voltage measurement of cable T-type joints; wherein, the equivalent capacitance between the conductive layer of the plug and the metal induction sheet is used as the first capacitance; the metal cavity and the metal induction sheet are used as the first capacitance. The gap capacitance between them is used as the second capacitance;

Obtain the capacitance value of the first capacitor, the capacitance value of the second capacitor, the resistance value of the measurement resistor and the voltage value across the measurement resistor according to the equivalent circuit model;

确定电缆导体的电压向量；According to the capacitance value of the first capacitor, the capacitance value of the second capacitor, the resistance value of the measuring resistor and the voltage value across the measuring resistor, the formula is

Determine the voltage vector of the cable conductor;

Determine the power frequency voltage of the cable joint according to the voltage vector of the cable conductor;

为电缆导体的电压向量，C₁为第一电容的电容值，C₂为第二电容的电容值，R为测量电阻阻值，

为测量电阻两端的电压值，ω为工频电压角频率，j为虚数单位。In the formula,

is the voltage vector of the cable conductor, C ₁ is the capacitance value of the first capacitor, C ₂ is the capacitance value of the second capacitor, R is the resistance value of the measuring resistor,

In order to measure the voltage value across the resistor, ω is the angular frequency of the power frequency voltage, and j is the imaginary unit.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

The device and method for measuring the power frequency voltage of the cable T-type joint provided by the present invention can determine the power frequency voltage of the measured cable joint in real time by acquiring the voltage signal of the measured resistance, thereby solving the needs existing in the prior art. It consumes a lot of manpower and material resources, and the problem of defective cable joints cannot be found in time.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative labor.

1 is a schematic structural diagram of a device suitable for power frequency voltage measurement of a cable T-joint provided by the present invention;

2 is a schematic structural diagram of a plug measuring module in an embodiment of the present invention;

Fig. 3 is the flow chart of the method that is applicable to the power frequency voltage measurement of the cable T-joint provided by the present invention;

4 is an equivalent schematic diagram of a circuit constructed according to the provided measuring device in an embodiment of the present invention;

FIG. 5 is a schematic diagram of an equivalent circuit constructed according to the provided measuring device in an embodiment of the present invention.

Symbol Description:

1 plug measurement module, 1-1 plug insulation layer, 1-2 plug conductive layer, 1-3 metal cavity, 1-4 metal sensor plate, 1-5 plug installation hole, 1-6 insulation film, 1-7 measuring resistance, 2 coaxial cable, 3 voltage determination module, 4 cable conductors, 5 cable connectors.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The purpose of the present invention is to provide a device and method suitable for measuring the power frequency voltage of a cable T-joint, so that the cable joint can be measured timely and accurately while saving manpower and material resources.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of a measuring device for power frequency voltage of a cable joint 5 provided by the present invention, and FIG. 2 is a structural schematic diagram of a plug measuring module 1 in an embodiment of the present invention. As shown in FIG. 1 and FIG. 2 , a measuring device suitable for the power frequency voltage of the cable joint 5 includes: a plug measuring module 1 and a voltage determining module 3 .

The plug measuring module 1 is installed at one end of the cable joint 5 . The plug measuring module 1 includes a measuring resistor 1-7 and a metal cavity 1-3. In the present invention, the thickness of the cavity wall of the metal cavity 1-3 is preferably 2-4 mm. The measurement resistors 1-7 are resistors whose resistance values are preferably 2kΩ-10MΩ.

A metal block is cut on the inner cavity of the metal cavity 1-3, and the metal block is pasted at the cutting position to serve as a metal sensor sheet. The measuring resistor 1-7 is placed in the metal cavity 1-3, one end of the measuring resistor 1-7 is connected to the wall of the metal cavity 1-3, and the other end of the measuring resistor 1-7 is connected to the metal sensing sheet. The voltage determination module 3 is connected with the measurement resistors 1-7, and the voltage determination module 3 is used for determining the power frequency voltage of the cable joint 5 according to the voltage signals at both ends of the measurement resistors 1-7.

As shown in FIG. 2 , the plug measuring module 1 further preferably includes: a plug insulating layer 1-1 and a plug conductive layer 1-2.

The plug conductive layer 1-2 is clamped on one end of the cable conductor 4 . The plug insulating layer 1-1 is the filling body of the plug measurement module 1, which is used to wrap the plug conductive layer 1-2 and the metal cavity 1-3.

In the present invention, in order to facilitate installation and disassembly, the above-mentioned plug insulating layer 1-1 is the insulating body of the plug, and its material is epoxy resin. A threaded structure is dug out at one end of the plug insulating layer 1-1 to fix the plug conductive layer 1-2. The conductive layer 1-2 of the plug then fixes the cable conductor 4.

Wherein, the material of the plug conductive layer 1-2 and the material of the metal cavity 1-3 are preferably conductive metal materials.

Preferably, the plug measuring module 1 further includes plug installation holes 1-5.

The plug installation hole 1-5 penetrates through the plug insulation layer 1-1 and the metal cavity 1-3, and the plug installation hole 1-5 is located in the cavity of the metal cavity 1-3 opposite to the position of the metal induction sheet 1-4 body.

The plug mounting holes 1-5 may also be the mounting hole structures in the existing plugs, and the purpose of opening them is to provide a contact surface for the torque wrench so as to facilitate fixing the cable conductor 4 .

Preferably, the measuring device further includes a coaxial cable 2 .

The coaxial cable 2 passes through the plug mounting holes 1-5, and one end of the coaxial cable 2 is connected to both ends of the measuring resistors 1-7, and the other end of the coaxial cable 2 is connected to the voltage determination module 3.

Preferably, the plug measuring module 1 further includes insulating films 1-6.

An insulating film 1-6 is attached to the side wall of the metal induction sheet 1-4. The insulating film 1-6 is smeared around the metal sensor sheet and then pasted at the incision in the wall of the metal cavity 1-3. The insulating film 1-6 is made of epoxy resin, which is used to separate the metal sensor sheet from the wall of the metal cavity 1-3.

Preferably, the voltage determination module 3 includes: a voltage calculation unit and a display unit.

The voltage calculation unit is respectively connected with the measuring resistors 1-7 and the display unit. The voltage calculation unit is used to determine the power frequency voltage according to the voltage signals at both ends of the measuring resistors 1-7. The display unit is used to display the power frequency voltage.

In view of the above-mentioned measuring device, the present invention also provides a method suitable for measuring the power frequency voltage of a cable T-joint. As shown in Figure 3, the measurement method includes:

Step 100: Build an equivalent circuit model according to the above-mentioned device suitable for measuring the power frequency voltage of a cable T-joint. As shown in Figure 4, the conductive layer of the plug is connected to the cable conductor and has an equipotential with the cable conductor. Wherein, the equivalent capacitance between the plug conductive layer and the metal induction sheet is used as the first capacitance. The gap capacitance between the metal cavity and the metal induction sheet is used as the second capacitance. The equivalent capacitance between the plug conductive layer and the metal cavity is taken as the third capacitance (the capacitance value is C ₃ ).

Step 200: Obtain the capacitance value of the first capacitor, the capacitance value of the second capacitor, the resistance value of the measuring resistor, and the voltage value across the measuring resistor according to the equivalent circuit model.

确定电缆导体的电压相量。Step 300: According to the capacitance value of the first capacitor, the capacitance value of the second capacitor, the resistance value of the measuring resistor, and the voltage value across the measuring resistor, use the formula

Determine the voltage phasors of the cable conductors.

Step 400: Determine the power frequency voltage of the cable joint according to the voltage phasor of the cable conductor.

为电缆导体的电压相量，C₁为第一电容的电容值，C₂为第二电容的电容值，R为测量电阻阻值，

为测量电阻两端的电压相量，ω为工频电压角频率，j为虚数单位。In the formula,

is the voltage phasor of the cable conductor, C ₁ is the capacitance value of the first capacitor, C ₂ is the capacitance value of the second capacitor, R is the resistance value of the measuring resistor,

To measure the voltage phasor across the resistor, ω is the angular frequency of the power frequency voltage, and j is the imaginary unit.

The specific process of implementing the above measurement method is as follows:

为等效电源电压相量，即电缆导体电压相量，

为电阻两端的电压相量。The potential of the conductive layer of the plug is regarded as the voltage source of the circuit, and the other parts are regarded as the external circuit, and the Thevenin equivalent is performed inside the power supply, ignoring the third capacitance, and the equivalent circuit of the measuring device under the power frequency is obtained, as shown in Figure 5. shown, Fig.

is the equivalent power supply voltage phasor, that is, the cable conductor voltage phasor,

is the voltage phasor across the resistor.

与戴维南等效电源电压相量，即电缆导体电压相量

之间的关系为：It can be known from the equivalent circuit that the voltage phasor at both ends of the resistance is measured

Equivalent power supply voltage phasor with Thevenin, that is, the cable conductor voltage phasor

The relationship between is:

Based on the above relationship, the power frequency voltage of the cable joint can be obtained.

Based on the above-mentioned technical solution provided by the present invention, the present invention has the following advantages compared with the prior art:

1. It can be directly modified on the plug of the cable connector without changing its original structure.

2. It has the characteristics of small size, wide application range and no geographical environment constraints.

3. The cable joints that are in poor operating state can be found in time, and the operator can deal with them without waiting for the failure to occur, which ensures the safe and stable operation of the entire cable system.

In addition, the above solutions provided by the present invention are preferably applicable to cable T-joints. Therefore, the specific embodiments of the present invention are all described by taking the cable T-joints as an example, but in the actual application process, those skilled in the art can also Applies to other types of cable glands.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The principles and implementations of the present invention are described herein using specific examples. The descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; meanwhile, for those skilled in the art, according to the present invention There will be changes in the specific implementation and application scope. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. The utility model provides a device suitable for cable T type connects power frequency voltage measurement which characterized in that includes: the device comprises a plug measuring module and a voltage determining module;

the plug measuring module is arranged at one end of the cable joint; the plug measuring module comprises a measuring resistor and a metal cavity;

cutting a metal block on the inner cavity of the metal cavity, and sticking the metal block at the cutting position to be used as a metal sensing piece; the measuring resistor is arranged in the metal cavity, one end of the measuring resistor is connected with the wall of the metal cavity, and the other end of the measuring resistor is connected with the metal sensing piece; the voltage determining module is connected with the measuring resistor and used for determining the power frequency voltage of the cable joint according to the voltage signals at the two ends of the measuring resistor.

2. The device of claim 1, wherein the plug measuring module further comprises: a plug insulating layer and a plug conductive layer;

the plug conducting layer is clamped at one end of the cable conductor; the plug insulating layer is a filling main body of the plug measuring module and is used for wrapping the plug conducting layer and the metal cavity.

3. The device suitable for measuring the power frequency voltage of the T-shaped joint of the cable according to claim 2, wherein the plug measuring module further comprises a plug mounting hole;

the plug mounting hole penetrates through the plug insulating layer and the metal cavity, and is located on the cavity of the metal cavity opposite to the metal induction sheet.

4. The apparatus of claim 3, wherein the measuring apparatus further comprises a coaxial cable;

the coaxial cable penetrates through the plug mounting hole, one end of the coaxial cable is connected with two ends of the measuring resistor, and the other end of the coaxial cable is connected with the voltage determining module.

5. The device for measuring the power frequency voltage of the T-shaped joint of the cable according to claim 2, wherein the material of the plug conducting layer and the material of the metal cavity are both conducting metal materials.

6. The device for measuring the power frequency voltage of the T-shaped joint of the cable as claimed in claim 1, wherein the plug measuring module further comprises an insulating film;

the insulating film is attached to the side wall of the metal sensing piece.

7. The device for measuring the power frequency voltage of the T-shaped joint of the cable as claimed in claim 1, wherein the measuring resistor is a resistor with the resistance value of 2k Ω -10M Ω.

8. The apparatus of claim 1, wherein the voltage determination module comprises: a voltage calculation unit and a display unit;

the voltage calculation unit is respectively connected with the measuring resistor and the display unit; the voltage calculation unit is used for determining the power frequency voltage according to the voltage signals at the two ends of the measuring resistor; the display unit is used for displaying the power frequency voltage.

9. The device suitable for measuring power frequency voltage of the T-shaped cable connector according to claim 1, wherein the thickness of the cavity of the metal cavity is 2-4 mm.

10. A method suitable for measuring power frequency voltage of a T-shaped joint of a cable is characterized by comprising the following steps:

the device suitable for measuring the power frequency voltage of the T-shaped joint of the cable according to any one of claims 1 to 9, wherein the device is used for constructing an equivalent circuit model; the equivalent capacitance between the plug conducting layer and the metal induction sheet is used as a first capacitance; a gap capacitor between the metal cavity and the metal induction sheet is used as a second capacitor;

acquiring a capacitance value of the first capacitor, a capacitance value of the second capacitor, a resistance value of the measuring resistor and voltage values at two ends of the measuring resistor according to the equivalent circuit model;

according to the capacitance value of the first capacitor, the capacitance value of the second capacitor, the resistance value of the measuring resistor and the voltage values at two ends of the measuring resistor, adopting a formula

Determining a voltage phasor of a cable conductor;

determining the power frequency voltage of the cable joint according to the voltage phasor of the cable conductor;

in the formula (I), the compound is shown in the specification,

is the voltage phasor of the cable conductor, C₁Is the capacitance value of the first capacitor, C₂Is the capacitance of the second capacitor, R is the resistance of the measuring resistor,

in order to measure the voltage phasor at two ends of the resistor, omega is the angular frequency of the power frequency voltage, and j is an imaginary number unit.

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