CN111896843A - A portable fault cable identification instrument - Google Patents

Abstract

The invention relates to a portable fault cable identification instrument, which is composed of a power cord, a current generator, a load electrical appliance and several connecting wires, and a clamp-type ammeter is required to be used in conjunction with the field test; the device is powered by alternating current 220V, and one end of the cable to be tested is Phase-to-earth, through the automatic and manual buttons, a current pulse signal with adjustable periodic frequency can be sent out, and the output will load the signal to the corresponding phase on the other end of the cable through the load appliance; when the current value displayed by the clamp-type ammeter matches the current signal sent When the period frequency values are the same, the target faulty cable can be determined. The invention has the characteristics of light, small, compact and portable, and is suitable for the detection of various types of high and low voltage cables, and has high-power current pulse output. .

Description

A portable fault cable identification instrument

technical field

The invention relates to a device capable of quickly identifying faulty power cables, belonging to the technical field of power line fault detection equipment.

Background technique

Power cables are widely used for power transmission and distribution in power systems. Especially in urban distribution networks and large industrial and mining enterprises, power cables are often laid in cable tunnels or cable trenches. There are often many cables of different voltage levels laid side by side in a cable tunnel. When the cable needs to be increased, transformed, or the line path is changed, especially when the faulty cable is repaired, it is necessary to determine the cable that needs to be repaired among multiple parallel cables. In the daily operation of the cable, the cable often encounters faults such as phase-to-phase short circuit, single-phase-to-ground short circuit, and open circuit. At present, the conventional processing method is to determine the location of the fault point through waveform analysis and calculation of the withstand voltage test of the faulty cable and the addition of the signal. When the weak position of the cable has insulation burnout and breakdown, and obvious traces appear on the surface, it can be judged as a faulty cable. If there are no obvious traces on the surface of the cable, it needs to be identified with the help of more advanced cable identification equipment. At present, the commonly used cable identification instruments on the market have high prices, and second, they have certain limitations, the accuracy rate is not high, and they are not suitable for identification and detection in some specific situations. It is often necessary to test the line outages one by one. In addition, the environment in the cable tunnel is complex and the interference is serious. Sometimes it takes up to five or six hours to distinguish a line, which seriously affects the reliability of the power supply and is time-consuming and labor-intensive. Therefore, how to quickly and accurately determine the faulty cable from the many cables running in the cable tunnel becomes a key problem.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device for quickly and accurately identifying faulty cables, which can improve work efficiency, quickly identify faulty cables in a short period of time, and ensure the safety of operators and the reliability of power supply.

In order to solve the above problems, the technical scheme adopted in the present invention is:

A portable fault cable identification instrument, comprising a casing, a cycle timing controller arranged in the casing for controlling the on-off of a current signal, a load electrical appliance connected with an output current signal of the cycle timing controller, the load electrical appliance and the cable to be detected One of the phase cores is connected, and the other phase core of the cable to be detected is grounded, and the load appliance is used to amplify the current pulse signal; the cycle timing controller uses the time base integrated circuit NE555, including power supply circuit, timing circuit and relay. Control circuit; the power supply circuit supplies power to the timing circuit and the relay control circuit, and provides the output current signal connected to the load electrical appliance; the timing circuit provides the timing function; the relay control circuit is used to issue a current pulse signal with adjustable periodic frequency.

A further improvement of the technical solution of the present invention is that the power supply circuit includes an output terminal L, a ground terminal N, an AC fuse FU, a power transformer T, a contactor KM, a rectifier bridge stack UR, a filter capacitor C3, and the second normally open contact of the relay K K3. Three-terminal voltage regulator integrated circuit IC2 and power-on indicator tube LED1. The output terminal L is externally connected to the load electrical appliance, one end of the AC fuse FU is connected to the output terminal L, the other end is connected to the input terminal of the power transformer T, and the other input terminal of the power transformer T is connected to The ground terminal N, the second normally open contact K3 of the relay K and the contactor KM are connected in series between the output terminal L and the ground terminal N, and the second normally open contact K3 is also connected in parallel with the manual button SB2; The output terminal is connected to the AC input terminal of the rectifier bridge stack UR. The DC output terminal of the rectifier bridge stack UR is connected with a filter capacitor C3 in parallel. The pin is connected to the negative pole of the DC output terminal of the rectifier bridge stack UR, the DC output pin of the three-terminal voltage regulator integrated circuit IC2 is connected to the automatic button SB1, and the other end of the automatic button SB1 is connected to the rectifier bridge stack through the first resistor R1 and the power-on indicator tube LED1. Negative terminal of UR's DC output.

The time base integrated circuit is the NE555 time base integrated circuit. The timing circuit includes the NE555 controller IC1, the first potentiometer RP1, the second potentiometer RP2, the first capacitor C1, the second capacitor C2, pins 4 and 8 of the NE555 controller IC1 The pins are connected to the output end of the automatic button SB1. The 2 feet of the NE555 controller IC1 are connected to the negative electrode of the first capacitor C1 and the second potentiometer RP2. The positive electrode of the first capacitor C1 is connected to the 4 of the NE555 controller IC1 through the normally closed contact K1 of the relay K. Pin 6 of the NE555 controller IC1 is connected to the first potentiometer RP1 through the second normally open contact K2 of the relay K. At the same time, the 6 pin of the NE555 controller IC1 is also connected to the negative electrode of the first capacitor C1, and the other of the first potentiometer RP1. One end is connected to the positive pole of the first capacitor C1; the other end of the second potentiometer RP2 is connected to the negative pole of the DC output terminal of the rectifier bridge stack UR; the 1 pin of the NE555 controller IC1 is connected to the negative pole of the DC output terminal of the rectifier bridge stack UR; Pin 5 is connected to the negative pole of the DC output end of the rectifier bridge stack UR through the second capacitor C2.

The relay control circuit includes the power input socket X, the relay K, the protection diode D, the second resistor R2, the output signal on-off indicator tube LED2, the 3 pins of the NE555 controller IC1 are respectively connected to the output signal on-off indicator tube LED2 and the coil of the relay K , Protection diode D, the other end of the output signal on-off indicator tube LED2 is connected to the negative electrode of the DC output end of the rectifier bridge stack UR through the second resistor R2, and the negative electrode of the DC output end of the rectifier bridge stack UR is also connected to the other end of the coil of the relay K, the protection the other end of diode D.

There are corresponding L and N terminals on the power input socket X. The output terminal L is connected to the L terminal of the power input socket X through the contacts of the contactor KM inside the housing, and the output terminal N is connected to the N terminal of the power input socket X. , the output end L is externally connected to the load electrical appliance; the power input socket X is inserted into the AC 220V socket through the power cord, and the power input socket X provides the output end L with AC220V power supply.

Both the automatic button SB1 and the manual button SB2 are located on the casing panel.

A further improvement of the technical solution of the present invention is that the automatic button SB1 performs cyclic on-off of the output signal with a period of 3s.

A further improvement of the technical solution of the present invention is that both the first potentiometer RP1 and the second potentiometer RP2 are adjustable resistors.

A further improvement of the technical solution of the present invention is that the first capacitor C1 and the second capacitor C2 are both capacitors with polarity, and the filter capacitor C3 is a capacitor without polarity.

A further improvement of the technical solution of the present invention is that the three-terminal voltage regulator integrated circuit is an LM7812 type three-terminal voltage regulator integrated circuit.

A further improvement of the technical solution of the present invention is that the power of the load electrical appliance is 5-10KW.

Owing to adopting the above-mentioned technical scheme, the beneficial effects obtained by the present invention are:

The invention can safely, conveniently and accurately identify one of the target cables from a plurality of cables, avoids serious accidents caused by mistakenly sawing live cables, provides reliable guarantee for cable maintenance and ensures the safety of operators.

The device needs to be used in conjunction with a clamp-type ammeter during on-site testing. The cable identification instrument is powered by AC 220V, and the current pulse signal with adjustable periodic frequency is sent out through the transformer and relay control circuit inside the instrument, which is loaded on a certain phase of one end of the cable to be tested through the load appliance, and the other end of the cable is grounded correspondingly to the phase. .

The device can control the output of the current pulse signal in two ways: automatic and manual. By pressing the automatic button, the device will generate a current pulse signal with a fixed period of 3s; by pressing the manual button, the cycle frequency of the current pulse signal can be controlled artificially.

The power of the load electrical appliance in the structure is 5KW. Through the load electrical appliance, the current pulse signal can be amplified to generate a single-phase current of about 20A.

The device can identify not only a single loop consisting of a single cable, but also a single loop consisting of two or more cables.

The working principle of the NE555 controller of this device, through the change of the high and low levels of the output pins of the NE555 circuit, controls the pull-in and disconnection of the relay K's moving and closing contacts, so that the controller circuit is repeatedly energized and de-energized, combined with LED2 Turn on and off the indication to control the output current signal on and off, and realize the purpose of cycle timing control.

Description of drawings

Figure 1 is the NE555 time relay control periodic on-off circuit;

Figure 2 is the output circuit of the contactor KM;

Fig. 3 is a single cable identification schematic diagram of the present invention;

Fig. 4 is the identification schematic diagram of two or more cables of the present invention;

The figures are marked as follows:

1. Load electrical appliances

2. Cable to be tested

3. Clamp ammeter

4. Cable identification instrument

FU, fuse fuse

T, power transformer

UR, rectifier bridge stack

C1, the first capacitor

C2, the second capacitor

C3, filter capacitor

RP1, the first potentiometer

RP2, the second potentiometer

LED1, power on indicator tube

LED2, output signal on-off indicator tube

D. Diode

K. Relay

X. Power input socket

K1, normally closed contact

K2, the first normally open contact

K3, the second normally open contact

KM, contactor

SB1, automatic button

SB2, manual button

R1, the first resistor

R2, the second resistor

IC1, NE555 controller

IC2, three-terminal voltage regulator integrated circuit.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments.

The present invention discloses a portable fault cable identification instrument, referring to Fig. 1-Fig. 4, comprising a casing, a cycle timing controller arranged in the casing for controlling the on-off of the current signal, and an output current signal of the cycle timing controller The connected load appliance, the load appliance is connected with one phase core of the cable to be detected, and the other phase core of the cable to be detected is grounded, and the load appliance is used to amplify the current pulse signal; the cycle timing controller utilizes the time base integration Circuit NE555, including power supply circuit, timing circuit and relay control circuit; the power supply circuit supplies power to the timing circuit and the relay control circuit, and provides the output current signal connected with the load electrical appliance, and the timing circuit provides timing function; the relay control circuit is used to send out the periodic frequency Adjustable current pulse signal.

in:

The power supply circuit includes the output terminal L, the ground terminal N, the AC fuse FU, the power transformer T, the contactor KM, the rectifier bridge stack UR, the filter capacitor C3, the second normally open contact K3 of the relay K, and the three-terminal voltage regulator integrated circuit IC2 It is connected to the power supply indicator tube LED1, the output terminal L is connected to the external load electrical appliance, one end of the AC fuse FU is connected to the output terminal L, the other end is connected to the input terminal of the power transformer T, the other input terminal of the power transformer T is connected to the ground terminal N, and the second terminal of the relay K is connected. The normally open contact K3 and the contactor KM are connected in series and connected in parallel between the output terminal L and the ground terminal N. The second normally open contact K3 is also connected in parallel with the manual button SB2; the output terminal of the power transformer T is connected to the AC of the rectifier bridge stack UR. The input end, the DC output end of the rectifier bridge stack UR is connected with a filter capacitor C3 in parallel, the DC input pin of the three-terminal voltage regulator integrated circuit IC2 is connected to the positive pole of the DC output end of the rectifier bridge stack UR, and the ground pin is connected to the DC output of the rectifier bridge stack UR. The negative pole of the terminal, the DC output pin of the three-terminal voltage regulator integrated circuit IC2 is connected to the automatic button SB1, and the other end of the automatic button SB1 is sequentially connected to the negative pole of the DC output terminal of the rectifier bridge stack UR through the first resistor R1 and the power-on indicator tube LED1.

The time base integrated circuit is the NE555 time base integrated circuit. The timing circuit includes the NE555 controller IC1, the first potentiometer RP1, the second potentiometer RP2, the first capacitor C1, the second capacitor C2, pins 4 and 8 of the NE555 controller IC1 The pins are connected to the output end of the automatic button SB1. The 2 feet of the NE555 controller IC1 are connected to the negative electrode of the first capacitor C1 and the second potentiometer RP2. The positive electrode of the first capacitor C1 is connected to the 4 of the NE555 controller IC1 through the normally closed contact K1 of the relay K. Pin 6 of the NE555 controller IC1 is connected to the first potentiometer RP1 through the second normally open contact K2 of the relay K. At the same time, the 6 pin of the NE555 controller IC1 is also connected to the negative electrode of the first capacitor C1, and the other of the first potentiometer RP1. One end is connected to the positive pole of the first capacitor C1; the other end of the second potentiometer RP2 is connected to the negative pole of the DC output terminal of the rectifier bridge stack UR; the 1 pin of the NE555 controller IC1 is connected to the negative pole of the DC output terminal of the rectifier bridge stack UR; Pin 5 is connected to the negative pole of the DC output end of the rectifier bridge stack UR through the second capacitor C2.

The relay control circuit includes the power input socket X, the relay K, the protection diode D, the second resistor R2, the output signal on-off indicator tube LED2, the 3 pins of the NE555 controller IC1 are respectively connected to the output signal on-off indicator tube LED2 and the coil of the relay K , Protection diode D, the other end of the output signal on-off indicator tube LED2 is connected to the negative electrode of the DC output end of the rectifier bridge stack UR through the second resistor R2, and the negative electrode of the DC output end of the rectifier bridge stack UR is also connected to the other end of the coil of the relay K, the protection the other end of diode D.

There are corresponding L and N terminals on the power input socket X. The output terminal L is connected to the L terminal of the power input socket X through the contacts of the contactor KM inside the housing, and the output terminal N is connected to the N terminal of the power input socket X. , the output terminal L is externally connected to the load appliance 1; the power input socket X is inserted into the AC 220V socket through the power cord, and the power input socket X provides the output terminal L with AC220V power supply.

For ease of understanding, referring to FIG. 2 , the L end of the power input socket X is marked as L1, and L1 passes through the contacts of the contactor KM to form L2, and L2 is the inside of the output end L. Correspondingly, the output end L is connected to the load electrical appliance 1 outside. .

The automatic button SB1 and the manual button SB2 are both located on the shell panel, and the automatic button SB1 performs a cycle of on-off of the output signal with a cycle of 3s; the first potentiometer RP1 and the second potentiometer RP2 are adjustable resistors; the first capacitor C1 and The second capacitor C2 is a capacitor with polarity, and the filter capacitor C3 is a capacitor without polarity.

The three-terminal voltage regulator integrated circuit is an LM7812 type three-terminal voltage regulator integrated circuit. Load electrical power is 5~10KW.

When the invention is used, the identification of the cable starts from the operation at both ends of the cable, and it must be ensured that the double numbers at both ends of the cable are accurate. Then remove the faulty cable terminals from the switch cabinets in the power distribution rooms at both ends, and ground one of the phases. When the location of the cable fault point is roughly determined, the target faulty cable should be found in the cables laid in parallel in the cable tunnel. The operation method of faulty cable identification is shown in Figure 3.

The cable identification device is plugged into the AC 220V power socket through the power cord, and the output end L is connected to a power 5KW load appliance 1, which can generate a large current. A current pulse signal with adjustable periodic frequency is sent out through the cycle timing controller (NE555 time relay control circuit) and added to one of the phase cores of the cable 2 to be tested. Press the automatic button SB1, the device will generate a single-phase current with a period of 3s and a size of about 20A. Test all the cables in parallel in the tunnel through the clamp ammeter 3. When the display of one of the cables changes with the trend of 0A--20A--0A--20A according to the 3s cycle, then this cable is the target cable.

Because the faulty cable is loaded with single-phase current, and the cable running normally in the cable trench is connected with three-phase alternating current, and the three-phase current is balanced. Under normal circumstances, when the cable 2 to be tested is tested with the clamp ammeter 3, the clamp ammeter 3 is theoretically not displayed. In actual situations, there are many cables laid in the cable trench, and the distance is close. Affected by the faulty cable, other cables in normal operation will also have induced current, but the value is smaller than that of the faulty cable. Especially when the three-phase unbalance occurs in the cable in normal operation or when there is a single-phase load affected by the production load, the current value that is the same as the set value period may appear. At this time, the on-off time of the current generator can be manually controlled by the manual button SB2 on the device, and the current display of the normal running cable and the faulty cable can be distinguished. Therefore, in practical applications, it is necessary to perform 0A--20A--0A--20A synchronous debugging and comparison multiple times, and control the current frequency automatically and manually to determine the final target cable.

In addition, the instrument can identify a single loop consisting of two or more cables. As shown in Figure 4. Connect the C phase of one of the same ends of the two cables 2 to be tested with the A phase of the other, and then the output end L of the cable identification instrument loads the current signal on one of the other ends of the cable 2 to be tested through the load device 1. On the C-phase of the root, the A-phase of the other cable is connected to the N-terminal of the cable identification instrument, thus forming a loop. In the same way as identifying a single cable, use the clamp ammeter 3 to test the sheath current of the cable respectively. When the displayed current value is the same as the set input current value, the two or more cables are the target cables to be identified. .

The fault cable identification instrument can easily, safely and accurately identify one or more cables that are out of power and waiting for repair among multiple cables running in parallel, providing a reliable guarantee for cable repair construction, and has the advantages of simple operation and high efficiency. It has the characteristics of high promotion and application value.

Claims (7)

1. The utility model provides a portable trouble cable identification appearance which characterized in that: the device comprises a shell, a cycle timing controller and a load electrical appliance, wherein the cycle timing controller is arranged in the shell and used for controlling the on-off of a current signal, the load electrical appliance is connected with an output current signal of the cycle timing controller, the other end of the load electrical appliance is connected with one phase core of a cable to be detected, the other phase core of the cable to be detected is grounded, and the load electrical appliance is used for amplifying a current pulse signal;

the cycle timing controller utilizes a time-base integrated circuit and comprises a power supply circuit, a timing circuit and a relay control circuit; the power supply circuit supplies power to the timing circuit and the relay control circuit and provides an output current signal connected with a load electrical appliance; the timing circuit provides a timing function; the relay control circuit is used for sending out a current pulse signal with adjustable periodic frequency.

2. The portable fault cable identification instrument of claim 1, wherein: the power supply circuit comprises an output end L, a grounding end N, an alternating current fuse FU, a power transformer T, a contactor KM, a rectifier bridge stack UR, a filter capacitor C3, a second normally-open contact K3 of a relay K, a three-terminal voltage-stabilizing integrated circuit IC2 and a power supply electrifying indicator tube LED1, wherein the output end L is externally connected with a load electric appliance, one end of the alternating current fuse FU is connected with the output end L, the other end of the alternating current fuse FU is connected with the input end of the power transformer T, the other input end of the power transformer T is connected with the grounding end N, the second normally-open contact K3 of the relay K and the contactor KM are connected in series and then connected in parallel between the output; the output end of a power transformer T is connected with the alternating current input end of a rectifier bridge stack UR, the direct current output end of the rectifier bridge stack UR is connected with a filter capacitor C3 in parallel, the direct current input pin of a three-terminal voltage-stabilizing integrated circuit IC2 is connected with the positive electrode of the direct current output end of the rectifier bridge stack UR, the grounding pin is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR, the direct current output pin of the three-terminal voltage-stabilizing integrated circuit IC2 is connected with an automatic button SB1, and the other end of the automatic button SB1 is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR sequentially through a first resistor R1 and a power-;

the time-base integrated circuit is an NE555 time-base integrated circuit, the timing circuit comprises an NE555 controller IC1, a first potentiometer RP1, a second potentiometer RP2, a first capacitor C1 and a second capacitor C2, 4 pins and 8 pins of an NE555 controller IC1 are connected with the output end of an automatic button SB1, 2 pins of the NE555 controller IC1 are connected with the negative electrode of the first capacitor C1 and the second potentiometer RP2, the positive electrode of the first capacitor C1 is connected with 4 pins of the NE555 controller IC1 through a normally closed contact K1 of a relay K, 6 pins of an NE555 controller IC1 are connected with the first potentiometer RP1 through a second normally open contact K2 of the relay K, meanwhile, 6 pins of the NE555 controller IC1 are also connected with the negative electrode of the first capacitor C1, and the other end of the first potentiometer 1 is connected with the positive electrode of a first capacitor C1; the other end of the second potentiometer RP2 is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR; a pin 1 of the NE555 controller IC1 is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR; a pin 5 of the NE555 controller IC1 is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR through a second capacitor C2;

the relay control circuit comprises a power input socket X, a relay K, a protection diode D, a second resistor R2 and an output signal on-off indicating tube LED 2; the 3 feet of the NE555 controller IC1 are respectively connected with an output signal on-off indicating tube LED2, a coil of the relay K and a protection diode D, the other end of the output signal on-off indicating tube LED2 is connected with the negative electrode of the direct current output end of the rectifier bridge stack UR through a second resistor R2, and the negative electrode of the direct current output end of the rectifier bridge stack UR is simultaneously connected with the other end of the coil of the relay K and the other end of the protection diode D;

the power input socket X is provided with a corresponding L end and an N end, the inner part of the output end L is connected with the L end of the power input socket X through a contact of a contactor KM in the shell, the output end N is connected with the N end of the power input socket X, and the outer part of the output end L is connected with a load electric appliance; the power input socket X is plugged in the AC220V socket through a power line and provides AC220V power for the output end L;

the automatic button SB1 and the manual button SB2 are located on the housing panel.

3. The portable fault cable identification instrument of claim 2, wherein: the automatic button SB1 cycles the output signal on and off at a period of 3 s.

4. A portable fault cable identification instrument according to claim 3, wherein: the first potentiometer RP1 and the second potentiometer RP2 are adjustable resistors.

5. The portable fault cable identification instrument of claim 4, wherein: the first capacitor C1 and the second capacitor C2 are both capacitors with polarity, and the filter capacitor C3 is a capacitor without polarity.

6. The portable fault cable identification instrument of claim 5, wherein: the three-terminal voltage-stabilizing integrated circuit is an LM7812 type three-terminal voltage-stabilizing integrated circuit.

7. The portable fault cable identification instrument of claim 6, wherein: the power of the load electrical appliance is 5-10 KW..

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