WO2012081938A2

WO2012081938A2 - Detonation system of a non-electric detonator using a spark detonation apparatus and blasting construction method using same

Info

Publication number: WO2012081938A2
Application number: PCT/KR2011/009743
Authority: WO
Inventors: 유선진
Original assignee: Yu Seon Jin
Priority date: 2010-12-16
Filing date: 2011-12-16
Publication date: 2012-06-21
Also published as: KR20120067823A; KR101230156B1; WO2012081938A3

Abstract

The present invention relates to blasting using a non-electric detonator performed in the field of tunneling, underground excavation, etc. More particularly, the present invention relates to a detonation system of a non-electric detonator using a spark detonation apparatus, in which an electric blasting machine and the spark detonation apparatus are implemented to detonate the non-electric detonator in an inexpensive, safe and reliable manner. The present invention also relates to a blasting construction method using the detonation system.

Description

Detonation system of non-electric primer using spark detonator and blasting construction method using same

The present invention relates to blasting using non-electric primers carried out in the field, such as tunnels and underground excavation, and more specifically to safely and reliably detonate non-electric primers at low cost using an electric blasting device and spark detonator. The present invention relates to a non-electric primer detonator system using a spark detonator and a blasting construction method using the same.

Excavation equipments used in underground excavation works such as tunnels and subways use high voltage electricity to minimize soot and dust generation, and the blasting method using electric primers inevitably exposes to electrical risks. .

In addition, lightning generated outside the tunnel is absorbed through the ground, and when a small current flows through the electric primer charged at the end of the tunnel, an unexpected explosion occurs, causing a terrible blasting accident that takes away precious lives.

In recent years, non-electric primers have been developed and used to safely blast from such electrical hazards. However, the conventional method of detonating non-electric primers for the first time requires expensive detonation costs, so in recent years, electrical hazards have been reduced. Even if the cost of detonation is low, the detonation method using a simple electric primer is implicitly used.

The characteristics and advantages and disadvantages of the two detonation methods will be briefly described as follows.

First, the traditional method of detonation is to connect a few hundred meters of signal tube called starter to the signal tube of the last non-electrical primer which was finally connected at the tunnel barrier, evacuate to the safety zone, and then explode shock or spark at the end of the signal tube. A method of igniting explosives in a signal tube by applying an impact.

This method is a very safe method of detonation from electrical installations inside the drilling tunnel or lightning from outside the tunnel.However, hundreds of meters of signal tubes are used at every blast, resulting in expensive detonation costs. This remains a problem for the environment.

Secondly, the detonation method using an electric primer is connected to the signal tube of the last non-electrical primer that was finally connected at the tunnel curtain, and the blast bus of several hundred meters is connected to each line of the electric primer to evacuate to the safety zone. By exploding the electric primer using an electric blasting machine to detonate the signal tube tied to the electric primer.

This method has the advantage of low cost of detonation and no environmental problems due to the use of permanently blasting busbars.However, only one electric primer makes expensive non-electrical primer installed in the entire membrane barrier. In addition, a single electric primer is a very irrational method of detonation, which is more sensitive to current than when the entire tunnel head is an electric primer and thus loses the fundamental purpose of making a non-electric primer.

The present invention solves the problems of the two methods of detonation described above and adopts only the advantages, which are electrically safe, low cost of detonation, and non-electrical using a spark detonator for detonating non-electric primers reliably even from a distance. It is to provide a detonation system of the primer and blasting construction method using the same.

In order to achieve the object as described above, the non-electric primer detonation system using the spark detonator according to the present invention is an electric blaster, a blast bus, a circuit inspection device and a spark detonator newly used in the blasting using a conventional electric primer Characterized in that consisting of.

In particular, the spark detonator is a detonator for igniting the signal tube by generating a strong spark on the signal tube of the non-electric primer after receiving a high-voltage current generated from the electric blast through a blast bus of several hundred meters.

In addition, the blasting construction method using the non-electric primer detonator system using the spark detonator according to the present invention is a non-electric primer detonator system using the spark detonator is a three-step process of installation, inspection, blasting step It is divided.

The installation step is to secure the safety distance from the scattering and wind pressure of the blasting rock by connecting the spark detonator to the signal tube finally connected at the tunnel curtain and connecting the blast bus of several hundred meters to the lead wire of the spark detonator.

The inspection step is to check whether there is an abnormality of the blasting circuit before connecting the blasting bus to the electric blasting device. Check the disconnection, short circuit, and normality of the blasting bus and spark detonator by using a normal conduction tester and resistance measuring device. Step.

In the blasting stage, after confirming that there is no abnormality in the electric circuit, connect the blast bus to the blast generator, charge the electric blast generator, and send a high-voltage current to the blast bus. Is ignited by a spark impact to detonate the non-electric primer.

The detonation system of the non-electric primer and the blasting construction method using the spark detonator made as described above have the following effects compared to the conventional detonation method using a conventional starter and detonation method using an electric primer.

First, the cost of detonation is low because no expensive signal tube is used.

Second, waste plastic signal tube does not occur, it is environmentally advantageous.

Third, it is safer than electric primer.

Fourth, because it is not explosives, it is easy to handle and store.

1 is a view showing the configuration of a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

Figure 2 is a perspective view showing the external appearance of the spark detonator of the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

Figure 3 is an exploded perspective view showing the configuration of the spark detonator of the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

4 is a perspective view and a cross-sectional view showing in detail the spark terminal of the spark detonator in the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

5 is a circuit diagram showing two embodiments of a blasting circuit of a spark detonator in a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

6 is a circuit diagram showing the most common use of varistors

FIG. 7 is a circuit diagram illustrating two embodiments in which a varistor is embedded in a blasting circuit of a spark detonator in a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

8 is a view showing the configuration of the housing and the vise cap of the spark detonator of the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

9 is a view showing the coupling of the housing and the vise cap of the non-electric primer detonation system using a spark detonator according to an embodiment of the present invention

10 is a perspective view showing a circuit inspection device [conduction tester and resistance measuring device] used in the blasting construction method using the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

11 is an exemplary view showing a state of inspecting a blast circuit using a conduction tester in the blasting construction method using a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention

12 is an exemplary view showing a state of checking a blasting circuit using a resistance measuring device in the blasting construction method using the sparking detonation system of the non-electric primer using the spark detonator according to an embodiment of the present invention

50: circuit inspection equipment [50-1: conduction tester, 50-2: resistance measuring instrument]

100: electric blasting machine 200: blasting bus 300: spark detonator

400: signal tube 500: tunnel close

30: upper and lower housings [30-1: vise rack, 30-2: vise protrusion,

30-3: Spark tip check groove, 30-4: Tightening male thread]

31: Vise cap [31-1: Signal tube insertion groove, 31-2: Slope tube,

31-3: Tightening female thread]

32: spark terminal 33: capacitor 34: safety resistor

35: varistor 36: lead wire 37: electromagnetic plate

The present invention relates to blasting using non-electric primers carried out at sites such as tunnels and underground excavations, and more particularly, to a spark detonation device and a non-electric primer using the same.

Looking at the detailed configuration of the spark detonator and the non-electric primer detonator system using the same through the accompanying drawings for the purpose of correct implementation of the present invention.

1 is a view showing the configuration of a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

This detonation system is the installation stage of connecting spark blasting device to the signal tube of the non-electric primer which was finally connected at the tunnel curtain and then connecting the blasting bus to the safety zone, and the blasting circuit consisting of spark detonating device and blasting bus It consists of a test step to check for abnormalities, and a blasting step of charging and blasting after connecting the blast bus to the blasting machine.

The configuration of the device for implementing the detonation system is composed of a circuit inspection device 50, an electric blasting device 100, a blast bus 200 and a spark detonator 300, etc. In particular, the spark detonator in the present invention It is the main component that occupies the core.

The spark detonator 300 receives a high-pressure current generated from the electric blasting machine 100 through the blast bus 200 of several hundred meters and then ignites the signal tube by generating a strong spark on the signal tube 400 of the non-electric primer. Looking at the structural features and the configuration of the parts as a detonator to make as follows.

Figure 2 is a perspective view showing the appearance of the spark detonator of the detonator system of the non-electric primer using the spark detonator according to an embodiment of the present invention.

Spark detonator 300 shown in the outer shape as shown in the figure is connected to the plastic housing for protecting the electronic component 30, the transparent plastic viscap 31 for binding the signal tube, and the blast bus It consists of the lead wire 36 which becomes.

3 is an exploded perspective view showing the configuration of the spark detonator of the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

Inside the housing 30 of the spark detonator made of a plastic injection molding is composed of a spark terminal 32, a capacitor 33, an electrical resistance 34, a varistor 35, a lead wire 36, an electromagnetic plate 37, etc. It consists of an electronic component and a viscap 31 of a transparent plastic material.

Looking at the specific role and characteristics of the electronic component as follows.

The spark terminal 32 is composed of two electrodes having a compact gap, and the two electrodes are inserted into the signal tube to receive a high voltage current generated by the electric blasting device and generate a strong spark in the signal tube. to be.

The capacitor 33 serves to temporarily accumulate and discharge a high-voltage current generated by the electric blast generator, and serves to allow a sufficient current to flow through the spark terminal by correcting a voltage lost through a long blast bus.

At this time, the capacitor used was a film capacitor without polarity, and the proper capacity of the capacitor was about 0.5 ~ 2uF (microfarad).

The capacitor is an accessory part that is selectively inserted according to the output voltage of the electric blast generator. When the high voltage electric blast generator having a high output voltage is used, the capacitor is not necessary.

The electrical resistance 34 provides a means for inspecting the abnormality of the blasting circuit and is an essential component used as a safety device for the spark amplification device in which a capacitor is inserted.

The electrical resistance used as a means of inspecting the blasting circuit is an essential component that must be built regardless of the presence or absence of a capacitor. The inspection method of the blasting circuit will be described in detail with reference to the drawings in the back of the chapter. Only electric resistance will be described.

The electrical resistance used as a safety device is an electronic component that must be inserted into a spark detonator with a built-in capacitor. When the spark does not occur due to a defective electrode of the spark terminal, it gradually discharges the charge accumulated in the capacitor.

For example, if the spark detonator fails to spark due to a poor electrode of the spark terminal, the explosive failure may cause the explosive operator to approach the tunnel barrier 500 to check for an abnormality of the blasting circuit. If the charge stored in the battery is discharged at once, an unexpected accident may occur.

Therefore, the electrical resistance is a part that plays an important role in gradually discharging the electric charges stored in the capacitor. The proper size of the resistance value was about 5KΩ ~ 1MΩ through experiments, and the safety resistance with this resistance value is applied to the spark terminal. The spark discharge was sufficiently caused, and if the spark discharge did not occur, the charge of the capacitor was completely discharged within 0.5 seconds.

The varistor 35, which is another safety device, is an electronic component that prevents current from flowing through the spark terminal under a certain voltage. The spark detonator does not react to an electrical installation flowing inside the tunnel or lightning generated from outside the tunnel. The spark detonator is a safety component that causes sparking only by the electric blast generator.

As other components, the lead wire 36 is a connecting wire for connecting the blast bus and the spark detonator, and the electromagnetic plate 37 connects and fixes the spark terminal, the capacitor, the electrical resistance, the varistor, and the lead wire to each other to form an electric circuit. Parts.

The structural features of the spark terminal causing spark in the signal tube of the non-electric primer is as follows.

4 is a perspective view and a cross-sectional view showing in detail the spark terminal of the spark detonator in the non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

As shown in the figure, the spark terminal 32 constitutes a spark tip 32-A composed of two electrodes 32-1 and 32-2 having a tight gap, and the distance between the two electrodes is an insulating coating 32-A. 3) is determined by the thickness.

The thickness of the insulating coating, that is, the spacing between the two electrodes, is closely related to the voltage causing the spark, and the larger the spacing between the two electrodes, the higher the voltage of the electroblasting apparatus is required.

The thickness of the insulation coating of the spark terminal used in the present invention was about 0.15 to 0.2 mm, and the required voltage for sparking in this gap was about 500V.

As shown in the figure, the spark tip 32-A consisting of two electrodes is inserted into the signal tube 400 to cause a strong spark to explode the octogen explosive 400-1 applied in the signal tube.

The main material of the spark terminal is brass or a similar conductive metal. Teflon wire or enameled wire is used for the insulation coated wire constituting the spark tip.

The types and roles of the components of the spark detonator have been described above, and the circuit configuration of each electronic component will be described below.

5 is a circuit diagram illustrating two embodiments of a blasting circuit of a spark detonator in a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

FIG. 5A is a circuit diagram of the spark detonator composed of only the spark terminal 32, the electrical resistance 34, and the lead wire 36. As shown in FIG.

Such spark detonator requires a high voltage blasting device of 3000V or more to compensate for the size of the spark depending on the thickness and length of the blast bus.

In addition, the electrical resistance 34 used for this circuit is an electronic component used as a means of inspecting the abnormality of a blasting circuit.

* In other words, if there is no electric resistance 34, there is no way to check the disconnection and short circuit of the blasting circuit connected to the blast bus and the spark device. Therefore, an electric resistance having a resistance value of several KΩ or more must be connected in parallel to the two wires. do.

5B is a circuit diagram of a spark detonator composed of a spark terminal 32, a capacitor 33, an electrical resistance 34, and a lead wire 36. As shown in FIG.

The spark detonator is such that the capacitor 33 is built into the electric circuit so that the spark can be generated even with a conventional electric blast within 1500V. The electric resistance 34 used at this time is a means for inspecting the abnormality of the blasting circuit. At the same time it is used as a safety device to discharge the charge of the capacitor.

Since the general spark detonator composed of the above components is not considered to be safe against surge currents caused by lightning strikes that may be applied from the high voltage electric facilities of about 500V or from outside the tunnel, such unexpected additions are not expected. There is a need for a spark detonator that is also safe against current.

In order to achieve this purpose, the varistor 35 is directly connected to the spark detonator so that the electronic circuit is cut below the required voltage, and the circuit is connected to generate the spark only when the required voltage is applied. It was made up.

6 is a circuit diagram showing the most common use of the varistor.

In general, the varistor 35 exists as a non-conductor connected in parallel to two wires of an electric circuit input terminal as shown in the circuit diagram. When a current of a specific voltage or more is applied, the varistor 35 becomes a conductor so that a high voltage current does not pass through the electric circuit or the ground. It is a variable resistance element that protects an electric circuit that allows current to flow to a portion.

However, in the present invention, unlike the above-mentioned purpose, the varistor is connected to one or two lines of the circuit input terminal in series so that the electric circuit is cut off below a specific voltage and the circuit is connected above a specific voltage. The spark detonator did not cause a spark at a current below the voltage.

The specific voltage is determined by the varistor specification according to the purpose of use. If the maximum voltage that can be applied during tunnel excavation is usually within 500V, the operating voltage of the varistor should be about 1000V in consideration of safety.

In other words, when a varistor operating at 1000V or higher is connected in series with a spark detonator, the spark detonator does not cause sparks for current within 1000V, so it is safe.The higher the output voltage of the blasting device, the safer the level of the varistor. It can be increased.

FIG. 7 is a circuit diagram illustrating two embodiments in which a varistor is embedded in the blasting circuit of the spark detonator in the detonator system of the non-electric primer using the spark detonator according to an embodiment of the present invention.

7 [A] is a diagram in which varistors are connected in series to one line in a circuit, and FIG. 7 [B] is a diagram in which varistors are connected in series to two lines in a circuit.

The circuit configuration of the spark detonator is described above, and the following is a description of the features and functions of the external configuration of the spark detonator.

8 is a view showing the configuration of the housing and the vice cap of the spark detonator of the detonator system of the non-electric primer using the spark detonator according to an embodiment of the present invention.

The housing 30 of the spark detonator is made of a plastic material that is light and easy to mold, and the housing is composed of a body portion 30-A for protecting the electronic component and a vice 30-B for coupling the signal tube. .

The configuration of the vise 30-B is a vise that adds the strength of tightening by the multi-parted vise rack 30-1, which serves to tighten the signal tube, and the inclined tube body 31-2 of the vise cap. The projection 30-2, the signal tube confirming groove 30-3 for checking whether the spark tip is inserted into the signal tube, and the fastening male screw 30-4 for fastening the vise cap are configured. It is done.

9 is a view showing a combination of the housing and the vise cap of the non-electric primer detonation system using a spark detonator according to an embodiment of the present invention.

When the vise cap 31 is fastened to the housing 30 as shown in the figure, the vise rack 30-1 is pressed against the inclined tube body 31-2 of the vise cap and tightly tightens the signal tube so that the signal tube does not fall out. .

Through the above drawings, the detailed configuration and operation of the spark detonator was examined. When the spark detonator and the signal tube are completely connected, the blast bus 200 of several hundred meters is connected to the lease line 36 of the spark detonator to evacuate to a safe distance. This completes the installation phase, the first phase of the detonation system.

10 is a perspective view showing a circuit inspection device (conductivity tester and resistance measuring device) used in the method for constructing a blasting using a spark detonation system using a spark detonation device according to an embodiment of the present invention.

The circuit tester may use the conduction tester 50-1 and the resistance meter 50-2 used in the conventional electric primer blasting, but the electric resistance inserted in the spark detonator has a resistance value of several KΩ. A high range of inspection equipment is required.

The conduction tester 50-1 is a simple circuit test device for checking the disconnection of the blast bus in the conventional electrical primer blasting.

This device checks whether the blast bus is disconnected according to the direction of the needle gauge.In the conventional blasting circuit using an electric primer, the needle gauge points to the left when the blast bus is broken, and when the blast bus is normal and short-circuited. In fact, it is difficult to check whether the blasting circuit is short-circuit in the right direction.

Therefore, in order to accurately check whether the blast bus is disconnected as well as whether the blast bus is short-circuited, the resistance measuring instrument 50-2 is used to determine the abnormality of the blast circuit by measuring the resistance value of the blast bus.

The resistance measuring instrument usually expresses the resistance value by digital number, and if the blast bus is disconnected, it shows 0 or infinity. If there is no abnormality in the blast circuit, the resistance value of the blast bus is displayed. It is smaller than the resistance value.

The inspection step, which is the second step of checking whether there is an abnormality in the blasting circuit composed of the blasting bus and the spark detonator, is as follows.

11 is an exemplary view showing a state of inspecting a blast circuit using a conduction tester in the blasting construction method using a non-electric primer detonator system using a spark detonator according to an embodiment of the present invention.

11A shows a case in which the blast bus 200 constituting the blast circuit is disconnected, and the needle of the conduction tester is pointing to the left side.

In general, the blast bus used in tunnel blasting has a length of at least 300m and is frequently broken by scattering of blasting rock. When the blasting circuit is checked with a conduction tester, the needle of the conduction tester points to the left.

This means that the electric current sent by the conduction tester cannot be returned through the blast bus, and the worker should find and connect the disconnected wire.

11B shows a case where the blast bus is shorted, and the needle of the conduction tester is pointing in the right direction.

This means that the minute current flowing through the continuity tester passes through the blast bus and returns to the continuity tester.

11 [C] is a diagram showing that the blast bus and the spark detonator are intact and the needle of the continuity tester is pointing to the center.

This means that a significant voltage drop occurred while the current of the continuity tester passed back through the blast bus and spark detonator. The direct cause of this phenomenon is due to the electrical resistance 34 inserted into the spark detonator. The larger the resistance value, the more the needle of the conduction tester is biased to the left. The smaller the resistance value is to the right.

Therefore, the resistance value of the electrical resistance inserted into the spark detonator should be in the range that can be checked by the conduction tester, and the resistance value of the needle of the conduction tester used in the conventional electric blasting is about 10-20KΩ.

12 is an exemplary view illustrating a state of checking a blasting circuit using a resistance measuring device in the blasting construction method using the sparking detonation system using a spark detonation device according to an embodiment of the present invention.

This method is similar to the method using the conduction tester described above, but differs in that it is represented by a number in the method of indicating the presence or absence of a blast circuit.

12 [A] is a picture of the case where the blast bus is disconnected, and is usually indicated by 0, and sometimes by a separate sign according to the production company.

Fig. 12B is a diagram in which the blast bus is shorted and is expressed as a resistance value up to the shorted part, and the maximum size of the shorted resistance is less than or equal to the maximum resistance of the blast bus.

12 [C] is a diagram illustrating a case where the blast bus and the spark amplification device have no abnormality, and the resistance value of the resistance meter is expressed as the sum of the resistance of the blast bus 200 and the resistance of the electrical resistance 34.

As described above, when there is no abnormality in the blasting circuit using the circuit inspection device, the blasting step is performed, which is the third step of blasting by connecting the blasting bus to the electric blasting device, and charges the electric blasting device to blast the high voltage current. When spilled into the mothership, the spark detonator causes a strong spark, and the signal tube connected to the spark detonator is ignited by the spark impact to detonate the non-electric primer.

The spark detonator is a consumable product that is directly buried by the blasting rock at every blasting because it is directly connected to the final signal tube at the tunnel face.

The non-electric primer detonation system using the spark detonator has less cost reduction and environmental pollution than the conventional detonation system using the starter, and it is electrically safer than the detonation system using the electric primer because it is only detonated by the high-pressure current blasting machine. .

The present invention having the same configuration as described above is an industrially useful invention that can safely and surely trigger non-electric primers at low cost.

Claims

Detonator circuit having a spark tip consisting of two electrodes to generate a spark by a high voltage current is configured therein to receive power from the electric blast through the blast bus to generate a spark in the spark terminal, the spark terminal In the non-electric primer detonation system using a spark detonator equipped with a spark detonator for transmitting the spark generated by the spark terminal to the non-electric primer installed in the tunnel through a signal tube connected to the spark terminal,

The detonator circuit includes two lead wires connected to the blast bus and electrically connected to each electrode of the spark tip, respectively.

Detonation system of a non-electric primer using a spark detonator, characterized in that the electrical resistance is connected between the two lead wires in parallel with the spark tip.
The method of claim 1,

The detonator circuit may further include a varistor connected between the electrical resistance and the spark tip at least one of the two lead wires with respect to a current equal to or greater than a predetermined voltage, in series with the spark tip. Detonation system of non-electric primer using spark detonator.
The method of claim 1,

The detonator circuit, a non-electric primer detonator system using a spark detonator, characterized in that the capacitor further connects between the two lead wires in parallel with the spark tip at a position between the electrical resistance and the spark tip. .
The method of claim 2,

The detonator circuit is a device in which at least one of the two lead wires is energized by a current equal to or greater than a predetermined voltage between the capacitor and the spark tip, and further includes a varistor connected in series with the spark tip. Detonation system of non-electric primer using detonator.
The method according to any one of claims 1 to 4,

The spark detonator includes an electromagnetic plate provided with the detonator circuit,

The body surrounding the electromagnetic plate and the spark tip of the detonation circuit are positioned and the signal tube is inserted into the spark tip and is formed in a conical shape having a smaller diameter toward the end thereof so that the end is divided into a vise rack. The housing provided,

And a vise cap for tightening the vise rack while being coupled to the conical vise so that the vise rack is tightened to couple the signal tube to the vise.
The method of claim 5,

The vise of the housing is formed with a signal tube confirmation groove that can confirm whether the spark tip is coupled to the signal tube at the position,

The vice cap is a non-electric primer detonator system using a spark detonator, characterized in that formed of a transparent material.
In the blasting construction method using the non-electric primer detonation system using a spark detonation apparatus using a spark detonation system using the spark detonation system of any one of claims 1 to 4,

An installation step of connecting the spark detonator to a signal tube of a non-electric primer that is finally connected at a tunnel curtain and connecting a blast bus to the spark detonator to evacuate to a safe distance;

An inspection step of checking the disconnection, short circuit, and normality of the blasting circuit by using a conduction tester or a resistance tester which is a circuit inspection device on the blasting bus and confirming that there is a disconnection or short circuit;

A blasting construction method using the sparking detonation system of the non-electric primer using a sparking detonator, characterized in that the blasting circuit is connected to the blasting bus after confirming that the blasting circuit is normal.
The method of claim 7, wherein

The inspection step is determined as disconnection when no current flows,

When conduction and resistance are detected by the resistance value based on the sum of the resistance of the blast bus and the electrical resistance of the blast circuit, it is judged as normal.

When the conduction and resistance caused by the resistance value lower than the resistance due to the sum of the resistance of the blasting bus and the electrical resistance of the blasting circuit are detected, the short circuit is determined. Blasting construction method.