"high voltage spark initiator for non-electric detonators"

Abstract

Disclosed is a high voltage spark initiator for non-electric detonators comprising of a Power Pack configured for generating high voltage impulse current; a down range initiator (DRI) disposed close to the blast site configured to generate spark due to corona discharge at atleast 1100 volts after receiving high voltage impulse current from power pack to initiate NONEL.

Description

[0001]LR-AAR-2618 “HIGH VOLTAGE SPARK INITIATOR FOR NON-ELECTRIC DETONATORS” FIELD OF INVENTION The present invention relates to a High Voltage Spark initiator for Non-Electric Detonators. More particularly, the present invention discloses a high voltage spark initiator configured for use with standard blasting cable with record of count of blast initiations for each tip. BACKGROUND ART The blasting is mainly performed at blasting sites for underground excavation and / or mining using non-electric detonators. Until now, detonation methods are carried out using starter detonators and percussion devices and detonation methods using spark detonators and electric detonators were used to detonate non-electric detonators. The detonation method using the starter detonator and percussion machine is expensive and leaves plastic waste, and the detonation method using the spark detonator and the electric blaster is inexpensive, but the voltage drops as the blasting bus length becomes longer and the blasting often fails. Currently for initiating non-electric detonators following methods are used 1) Plain Ordinary Detonator 2) Electric Detonator 3) Detonation cord 4) Electronic Detonator 5) Percussion primer 6) Percussive electric match 7) Electrical Spark Ignition LR-AAR-2618 The aforesaid detonation methods 1 to 6 are methods where explosives are used, but the method 7 is a non-explosive method. Current devices available for method 7 have a few problems – 1) The blasting cable used to connect downrange initiator with the powerpack needs to be of particular specification. 2) Charging time of down range initiator is high 2 to 3 seconds. 3) The tip used to create a spark is either complex to arrange or may be unreliable as there is no counter associated with the tip as to how many initiations has it done. The tip has a finite life and hence without a counter the user may not know how many imitations have been done The present invention constitutes a means for directly or indirectly detonating a non-electric detonator to an electric initiator in order to solve the above problems, and a non-electric detonator blaster and detonator configured with a High Voltage Spark initiator configured for use with standard blasting cable with record of count of blast initiations for each DRI / ESI tip capable of operating the electric blaster from a distance provide the system. The non-electric detonator initiator and the detonation system using the same have the effect of safely and reliably detonating the non-electric detonator at a low detonation cost from a long distance. The added advantage is that a reusable blasting cable can be used to detonate the non-electric detonator from a distance reducing costs significantly. In the prior art, an US specification US6196131B1 discloses a non-electric initiator tip for use with a non-electric shock tube initiation device. The initiator tip of the present invention comprises an inner electrode, an outer LR-AAR-2618 electrode, and a conductive component electrically coupled to the inner and outer electrodes for applying current to the inner and outer electrodes to thereby cause a percussion spark to be generated. When the initiator tip is connected to an initiation device, the conductive component of the initiator tip is electrically coupled to electronics in the initiation device such that, when the initiation device is actuated, the electronics in the initiation device in conjunction with a power supply cause a voltage differential to be generated between the inner and outer electrodes and a percussion spark to be produced. The percussion spark initiates gun powder contained in a shock tube mounted to the initiator tip. In accordance with one embodiment of the present invention, the initiator tip comprises an inner electrode made of a material having a high melting point, such as, for example, steel / nickel alloys (e.g., stainless steel SS-304, SS-306), chromium / molybdenum alloys, Tungsten, etc. In accordance with another embodiment of the present invention, the initiator tip is encased in an insulative material to eliminate any possibility of electric shock to a person handling the initiation device. In another prior art, there is also provided an US specification US20040025735A1 which discloses Multiple independent penetrating electrode non-electric tips in which the electrodes are separated in a non-coaxial arrangement so as to generate a spark gap internal to the non-electric shock tube, with the electrodes being brought together inside of the shock tube at a very precise distance, improving longevity by eliminating ablation of the insulating material between the inner and outer electrodes, reducing electrical shorting of the electrodes, and providing more consistent and reliable ignition of shock tubes. SUMMARY OF INVENTION LR-AAR-2618 The principle object of the present invention is to design of the power pack (Blasting unit) and down range initiator (DRI) such that any standard blasting cable can be used for length upto 2 km. Another object of the present invention is to provide a power pack configured to give a high voltage initiator which charges the down range initiator in 2 to 3 millisecond which is 1000 times faster than available. Yet another object of the present invention is to provide a tip including an embedded microcontroller configured to maintain the count of initiation as well as health of the tip. In the present invention the DRI may be armed through an electronic signal. In an exemplary embodiment, after arming is done then only any stimulus can cause the spark. In another embodiment the Power Pack needs to be armed before the Power pack send`s a High Voltage signal to initiate the DRI / ESI Tip. The Power Pack gets armed by an encoded signal generated by the DRI`s Microcontroller. The disclosed initiator has the advantage of low cost of detonation and no environmental problems due to the use of high voltage initiator instead of conventional permanently blasting busbars. Therefore such as herein described there is provided a high voltage spark initiator for non-electric detonators comprising of a Power Pack configured for generating 3.5 kv to 4.5 KV high voltage impulse current; a down range initiator (DRI) disposed close to the blast site configured to generate spark due to corona discharge at atleast 1100 volts after receiving high voltage impulse current from power pack to initiate NONEL BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS LR-AAR-2618 Fig 1(a) illustrates the different components used for said high voltage spark initiator for non-electric detonators in accordance with the present invention; Fig 1(b) illustrates the Down Range Initiator in accordance with the present invention; Fig 1(c) illustrates the Power Pack which was used in the testing in accordance with the present invention; Fig 2 illustrates the functional diagram of the initiator in accordance with the present invention; Fig 3 illustrates the functional diagram of the metal tube of the ESI tip in accordance with the present invention; Fig 4(a) illustrates the circuitry of the power pack in accordance with the present invention; Fig 4(b) illustrates the functional diagram for the circuitry of the power pack in accordance with the present invention; Fig 5(a) illustrates the circuitry of the down range initiator in accordance with the present invention; Fig 5(b) illustrates the functional diagram of the down range initiator in accordance with the present invention; Fig 6(a) illustrates the circuit to read voltage fluctuations present in both DRI and power pack in accordance with the present invention; Fig 6(b) illustrates the circuit to create encoded signal through current / voltage fluctuations present in both DRI (optional) and power pack in accordance with the present invention; Fig 6(c) illustrates the arming circuit of down range initiator in accordance with the present invention. DETAILED DESCRIPTION The present invention relates to a High Voltage Spark initiator for a non- electric detonator that can safely and reliably detonate a non-electric detonator from a long distance, and a detonation system using the same. LR-AAR-2618 The blasting unit is configured for providing the electronic initiator through the at least one wire with an initiation voltage which is sufficient to initiate the non- electric detonator / shock tube , and with the proper digital codes that the electronic initiator can identify and understand to execute the functions ordered by the blasting unit. Therefore, the present invention provides a reliable and safe way to initiate non-electric blasts remotely. According to the invention, the blasting unit is capable to initiate the at least one electronic initiator connected thereto and, in consequence, initiating the at least one shock tube attached and held by the retaining means of the external housing in a use situation of the firing system. In an embodiment of the invention the retaining means of the electronic initiator comprise at least one tip adapted to receive at least one shock tube. In a preferred embodiment the at least one slot is situated adjacent to the explosive charge. In an embodiment of the invention there is provided a Reusable / onetime Electric Spark Initiator (ESI) Tip configured to generate a spark due to corona discharge when a voltage of at least 1100 Volt is applied. It does not contain any active energy components like capacitors / batteries. The tip includes a counter configured to count the number of firings. In an embodiment of the invention the firing system includes a plurality of electronic initiators connected to the blasting unit. In an embodiment the electronic initiators are programmable to initiate respective blasts sequentially in time. Advantageously, it is also thus possible to assign time sequences between the plurality of electronic initiators connected to the blasting unit. LR-AAR-2618 In an embodiment, the firing system comprises a plurality of blasting units and a plurality of electronic initiators, each blasting unit being connected to at least one electronic initiator. In an embodiment the blasting units are programmable to initiate the electronic initiators sequentially in time. In an embodiment the blasting unit comprises communication means configured to allow communication with at least one additional blasting unit. In a preferred embodiment the communication means are configured to allow bidirectional communication between at least two blasting units, such that instructions and / or commands can be sent between them. The communication interface of the communication means can be wired or wireless. In a preferred embodiment the communication means are configured to operate in ad-hoc mode and / or in infrastructure network. High Voltage Spark Initiator for Non electric Detonators This system can initiate non electric detonator without using any explosive initiator like electric / electronic detonator. This has been developed indigenously for Indian environment. The system contains 3 units as shown in fig 1(a - c). 1) A battery powered electronic device (Power Pack) as shown in Fig 1(c), which discharges 10-20 joules of energy at more than 3500 Volts. Battery used are lithium-ion batteries of 9 V to 12.4 V. 2) A down Range one time / multiple use initiator as shown in Fig 1(b) and further working at Fig 2 have capacitors and other electronic components. This down range initiator charges after it receives an input of more than 3.5kv form the power pack. After charging it outputs a current of more than 1100 V. 3) A Reusable / onetime Electric Spark Initiator (ESI) Tip (as shown in Fig 3 is configured to generate a spark due to corona discharge when a voltage LR-AAR-2618 of at least 1100 Volt is applied. It does not contain any active energy components like capacitors / batteries. This ESI Tip is integrated with the DRI. The operation of the system 1) The Metal tube of the ESI tip is of diameter 1 mm as shown in Fig 3. This tube is inserted inside the shock tube (PETN / HMX) which is close to the blast holes. 2) The Red and black connectors are then connected with one end of the short firing cable. 3) After the blast site is vacated, the other end of the short firing cable is connected with the power pack. The length of the cable is typically 100 -400 meters can go up to 2 Km. 4) The Power Pack then communicates with the down range initiator (DRI) to enquire about the status and health of the initiator, after all is ok it gets armed and then in a certain version of the invention, The power pack may arm the initiator and proceeds to the next step. 5) In a different version of the invention the power pack gets armed by the DRI before taking the DRI to the blast site through encoded signals generated by the DRI. 6) The power pack is then charged with the help of a battery and a high voltage dc-boost converter to 3500+V. After charging is complete the exploder discharges the entire energy into the ESI Tip causing a spark. 7) After the blast is successfully initiated all connections are disconnected and the ESI tip is recovered from the site and can be reused for the next blast. Advantages- 1) Electric detonator which are used currently for initiation of Non Electric Detonator (NONEL) pose a substantial safety risk as they are susceptible to stray currents LR-AAR-2618 2) Electric detonators are being phased out worldwide as well as in India and alternates are required by the mining Industry Power Pack Component level design as shown in Fig 4 - 1) Battery Pack of 9V to 12V which will power the Microcontroller, the peripheral circuits and High voltage generator 2) Micro Controller – (1) Will read information from the peripheral circuit – “Circuit to read the incoming encoded signal through current fluctuation”. Based on the binary digits (digital signal) (serial number of the Down range Initiator / DRI) received from this circuit the microcontroller will determine the health of the DRI, including its functionality, the number of times the DRI has been used, the arming status etc. After each successful initiator the microcontroller will store information regarding the number of times the particular DRI has been used (2) Will send information to the DRI through (Fig 6(b))– “Circuit to create encoded signal through current / voltage fluctuations”. After Checking the status of the DRI and after finding it ok the Power Pack will get armed. The microcontroller may initiate the process of arming the DRI depending on the version of the system. For this an encoded binary / digital signal through current / voltage fluctuations will be send to the DRI (3) After receiving information from the DRI that arming has been successful, the microcontroller will activate the HIGH voltage generator which will charge the Capacitor to 4KV+ (4) After charging is complete the microcontroller will indicate to the user that the charging is complete and then the user through a mechanical switch discharge the energy stored in the capacitors into the DRI LR-AAR-2618 3) HIGH voltage generator – generates 4KV + voltage to charge the capacitors 4) Input Output terminals – 2 terminals in which a 2 core cable as shown in Fig 1(a) is of resistance less than 300 ohms is connected to transmit and receive signals 5) Circuit to read the incoming encoded signal through current fluctuation- A circuit which may consist of resistors, transistors, diodes and comparators which can sense a change in overall resistance of the complete system (including the DRI) and generate a digital output . 6) Circuit to create encoded signal through current / voltage fluctuations - - A circuit which may consist of resistors, transistors, diodes which can change the overall resistance of the system including DRI. Down Range Initiator (DRI) Component level design as shown in Fig 5- 1) Input Output terminals – 2 terminals in which a 2 core cable of resistance less than 300 ohms is connected to transmit and receive signals 2) Circuit to read the incoming encoded signal through current fluctuation (Fig 6(a)) (optional)- A circuit which may consist of resistors, transistors, diodes and comparators which can sense a change in overall resistance of the complete system (including the DRI) and generate a digital output. 3) Circuit to create encoded signal through current / voltage fluctuations (Fig 6(b)) - - A circuit which may consist of resistors, transistors, diodes which can change the overall resistance of the system including DRI. 4) Arming Circuit - Fig 6(c) (optional)- – The circuit which consists of relays, SCR, transistors, capacitors. The circuit is designed such a way that until an arming signal is received from the power pack to the microcontroller it will not activate the connection of the input terminals to the capacitors. This arming circuit may be time dependent that after arming the circuit will automatically get disarmed after certain time duration. LR-AAR-2618 5) Microcontroller i) Receives power from input / output terminals. ii) Sends a unique serial number to the powerpack through - Circuit to create encoded signal through current / voltage fluctuations iii) Receives a signal for arming from power pack through Circuit to read the incoming encoded signal through current fluctuation (optional). iv) Activates the arming circuit after signal is received(optional) 6) High voltage switch- This may contain a gas discharge Tube, Electrically activated spark switch etc. the function is to activate when the desired voltage of at least 1100 Volts is reached in the capacitors. Inventive step Because of the design of the power pack (which will generate 4000v) and down range initiator (which will charge quickly) the initiation process will be smooth and similar to electric detonators. Also the microcontroller will record the blast initiations in the DRI / ESI tip which will make the system highly reliable. Also feature of option al arming is there which will make the device safer(prevent accidental initiations) and will make it more secure that is unauthorized personal will not be able to use the same. Uses: 1) For initiating Non-electric detonators 2) For initiating ordinary detonators 3) For using as a trunkline initiator for non-Electric detonators Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having LR-AAR-2618 ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

LR-AAR-2618 CLAIMS:

1. A high voltage spark initiator for non-electric detonators comprising of: a Power Pack configured for generating high voltage impulse current; a down range initiator (DRI) disposed close to the blast site configured to generate spark due to corona discharge at atleast 1100 volts after receiving high voltage impulse current from power pack to initiate non-electric detonator [NONEL]; wherein said power pack and down range initiator (DRI) are connected with each other through standard 2 core blasting cable.

2. The high voltage spark initiator as claimed in claim 1, wherein said power pack is disposed at a remote location from blast site.

3. The high voltage spark initiator as claimed in claim 1, wherein said 2 core blasting cable is of the length of the cable typically 100 -400 meters and total resistance at least less than 300 ohms.

4. The high voltage spark initiator as claimed in claim 1, wherein the blasting count for each DRI is maintained.

5. The high voltage spark initiator as claimed in claim 1, wherein said power pack will only get armed / charged after enquiring about the serial number of the DRI and finding out the health and time of use of the DRI.

6. The high voltage spark initiator as claimed in claim 1, wherein said DRI will have an arming feature which will only get activated by an encoded signal from the powerpack; and wherein said Power Pack is configured for generating 3.5 kv to 4.5 KV.LR-AAR-2618 7. The high voltage spark initiator as claimed in claim 1, wherein said down range initiator (DRI) is configured for one time or multi time use.

8. The high voltage spark initiator as claimed in claim 1, wherein said charging time of said DRI is very small from 2 to 3 milliseconds.

9. The high voltage spark initiator as claimed in claim 1, wherein the arming procedure is carried out in either Power Pack or DRI or both; and wherein said arming procedure for both in the Power Pack and DRI are different.

10. The high voltage spark initiator as claimed in claim 9, wherein only after arming only the DRI is being activated to initiate NONEL.

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