Title of Invention

"A MULTI-CHANNEL INTRINSICALLY SAFE REAL-TIME MONITORING SYSTEM FOR UNDERGROUND MINES"

Abstract

The microprocessor based multi-channel intrinsically safe real-time environmental monitoring system of the present invention will be particularly useful for underground mines. The system of the present invention is capable of providing real-time monitoring of different environmental parameters such as temperature, air velocity, machine status, methane, carbon monoxide at a plurality of locations even in a big underground mine. The system of the present invention enables two-way communication, which is very much essential for taking up appropriate control action whenever required from the surface. The system also provides on-line visual representation of trend of all the monitored parameters and gives audio-visual warning signal when a particular parameter crosses the respective threshold limit so that mine management can immediately take appropriate action. This would also help in enhancement of productivity and profitability of a mine, proper ventilation planning, early detection of fire, indicating occurrence of high concentration of gases, reducing the response time and minimizing dependence on human errors

Full Text

The present invention relates to a multi-channel intrinsically safe real-time environmental monitoring system for underground mines. The present invention particularly relates to a microprocessor based multi-channel intrinsically safe realtime environmental monitoring system for underground mines. The microprocessor based multi-channel intrinsically safe real-time environmental monitoring system of the present invention is particularly useful for underground mines. Installation of the system of the present invention in an underground mine would help the mine management to monitor production rate, environmental condition and concentration of gases in the underground mine from the surface control room. This would also help in proper ventilation planning, early detection of fire, indicating occurrence of high concentration of gases, reducing the response time and minimizing dependence on human errors and effective enhancement of productivity and profitability of a mine. The hitherto known prior art generally related to data acquisition and environmental monitoring in underground mines may be referred to in the following patent and literature references. Reference may be made to an Indian patent application number 174 / DEL / 95, titled "A data acquisition system useful for underground mines", wherein a system has been described and claimed for acquisition of data from underground mines. The literature references to the above system are also given in: Bandyopadhyay, L.K., Srivastava, S. and Srivastava, S.C.: 1989, 'Application of computers for online monitoring and control in coal mines', In: Proc. of Industrial Conference on Computer Application in Mineral Industry (Eds.Ghose, A., Misra, D.D. and Mazumdar, T.), 6-7 January 1989, MGMI publications,Calcutta, pp. 157-161. Srivastava, S., Sinha S. and Bandyopadhyay, L.K.: 1991, 'Microprocessor based switching of intrinsically safe power from surface to underground methane sensor in down link and data from underground to surface in up link in same pair of conductor', Research and Industry, 36: 268-270. Bandyopadhyay, L.K., Srivastava, S., Sinha, S., Dutta, M.K., Tudu, E., Sinha, S.K. and Srivastava, S.C.: 1992, 'Experience with indigenous microprocessor based data acquisition system for underground mines', Research and Industry, 37: 54-56. Bandyopadhyay, L.K. and Banerjee, G.: 2000, 'Integrated mine environmental monitoring system towards development of a decision support system', In: Proc. of Mine Environment and Ventilation Symposium (Ed. Panigrahi, P.C.), Organised by Indian School of Mines, Dhanbad, 11-12 December 2000, Oxford & IBM, Kolkata, pp. 89-97. Bandyopadhyay, L.K.: 2001, 'Integrated mining information and control systems: towards the digital mine', In: Proc. of Third Indian Conference on Computer Applications in Mineral Industry (Eds. Bandopadhay, C and Sheorey, P.R.), Organised by Central Mining Research Institute, Dhanbad, 17-18 March 2001, Oxford & IBH, New Delhi, pp. 187-192. Bandyopadhyay, L.K., Kumar, S. and Singh, A.K.: 2001, 'Computerised mine environmental monitoring system for underground coal mines', In: Proc. of the International Conference on Mechanistion and Automation - The Future of Mineral Industry (Eds. Bose, L.K., Mitra, D., Ghose, S., Dutta, A.K., Choudhury, A., Deb, T.K. and Dasgupta, K.), Organised by Mining, Geological and Metallurgical Institute, 26-28 July 2001, IRIS Communications, Kolkata, pp. 209-212. The drawbacks of the hitherto known prior art, as referred above are accessibility of only eight number of channels which restricts the system to monitor four parameters at maximum of two places; consumption of more power by the system because each channel is connected to a particular sensor through its own signal processor and power source; availability of only four sensors, viz. temperature, air velocity, machine status and methane; consumption of more electric power by methane sensor having less sensitivity, absence of visual display capacity of the system to see the trend and bar chart of the monitored data; and inability for two-way communication of the system which is essential for real-time monitoring. The main object of the present invention is to provide a multi-channel intrinsically safe real-time environmental monitoring system for underground mines which obviates the drawbacks as detailed above. Another object of the present invention is to provide a microprocessor based multichannel intrinsically safe real-time environmental monitoring system for underground mines which obviates the drawbacks as detailed above. Yet another object of the present invention is to provide a microprocessor based multi-channel direct measurement of environmental parameters at a plurality of locations by a single system for an underground mine. Still another object of the present invention is to provide a real-time environmental monitoring system with reduced consumption of power. Still yet another object of the present invention is to provide all the five essential environmental parameters for underground mines, namely temperature, air velocity, machine status, methane and carbon monoxide for real-time continuous monitoring. A further object of the present invention is to provide on-line visual representation of trend of all the monitored parameters and give audio-visual warning signal when a particular parameter crosses the threshold limit to enable the mine management to take appropriate action immediately. A still further object of the present invention is to provide two-way communication between surface computer and underground data station for effecting changes in the underground system from the knowledge of measured parameters. The microprocessor based multi-channel intrinsically safe real-time environmental monitoring system of the present invention will be particularly useful for underground mines. The system of the present invention is capable of providing real-time monitoring of different environmental parameters such as temperature, air velocity, machine status, methane, carbon monoxide at a plurality of locations even in a big underground mine. The system of the present invention enables two-way communication, which is very much essential for taking up appropriate control action whenever required from the surface. The system also provides on-line visual representation of trend of all the monitored parameters and gives audio-visual warning signal when a particular parameter crosses the respective threshold limit so that mine management can immediately take appropriate action. In the drawings accompanying this specification: Figure 1 shows the block diagram of the complete system (1) to (20) of the present invention. Figure 2 represents block diagram of the data station (1). Figure 3 represents circuit diagram of multi-channel selector (4). Figures 4 to 8 represent circuit diagrams of temperature (7), air velocity (8), machine status (9), methane (10) and carbon monoxide (11) sensors, respectively. The details of the figures 1 to 8 of the drawings are given below: The block diagram as depicted in figure 1 of the electronic hardware of the microprocessor based multi-channel intrinsically safe real-time environmental monitoring system of the present invention for underground mines consists of: microprocessor based data station (1), which is kept in the underground (2) and connected to an intrinsically safe power supply of 5 V D.C. (3). A multi-channel selector (4) and data communication link (5). Output (6) of the sensors, namely temperature (7), air velocity (8), machine status (9), methane (10), carbon monoxide (11) and other optional sensors (12-14) are connected to the multi-channel selector (4). The sensors are powered by intrinsically safe power supply (15) through 5 V D.C. connector (16). The signal processors of the sensors are connected using 12V D.C. intrinsically safe power cable (17). On the surface (18) of an underground mine (2), a computer (19) is connected through data link (5) for collecting data and two-way communication from surface (18). A printer (20) is attached with the computer (19) for taking the printout of data as well as graphs, using a software developed in higher level and assembly languages for collecting, processing and storing of data as per the requirement. The block diagram as depicted in figure 2 of the data station (1) comprises: microprocessor (21), memory (22), digital input/output device (23), analog input/output (24), serial communication port (25), keyboard/display interface (26), data bus (27), 5 V D.C. power supply (28), address bus (29), control bus (30). Figure 3 represents the circuit diagram of multi-channel selector (4) which consists of: parallel port (31), decoder (32), driver (33), analog to digital port (34), relay (35), signal processor (36), 12 V (D.C.) power supply (37), multi-channel input (38). Figures 4 to 8 shows details of the circuit diagrams of the temperature sensor (7); air velocity sensor (8); machine status sensor (9); methane sensor (10); and carbon monoxide (11) sensor, respectively. Accordingly the present invention provides a multi-channel intrinsically safe real-time environmental monitoring system for underground mines, which comprises electronic hardware located in an underground mine (2) essentially consisting of a microprocessor based data station (1) connected respectively to an intrinsically safe 5 V D.C. power supply (3), data communication link (5) capable of transmitting data and providing two-way communication, and a multi-channel selector (4); the said multi-channel selector (4) being connected to outputs (6) of a plurality of sensors such as temperature (7), air velocity (8), machine status (9), methane (10), carbon monoxide (11) and other optional sensors (12-14); the sensors being powered by intrinsically safe power supply (15) through 5 V D.C. connector (16) and sensor signal processors being connected through 12 V D.C. intrinsically safe power cable (17); the said data station (1) being connected through the said data communication link (5) to a computer (19) and a printer (20) on the surface (18) of the said underground mine (2), In an embodiment of the present invention the data station (1) capable of receiving and transmitting data consists of: microprocessor (21), memory (22), digital input/output device (23), analog input/output (24), serial communication port (25), keyboard/display interface (26), data bus (27), 5 V D.C. power supply (28), address bus (29), and control bus (30) duly interconnected to function as a data station; the said analog input/output (24) being connected through the multi-channel selector (4) to sensors (7-14) and the said serial communication port (25) being connected through the data communication link (5) to the computer (19). In another embodiment of the present invention the multi-channel selector (4) capable of receiving and transmitting data from the sensors (7-14), comprises: parallel port (31) interfaced to data station (1), the said parallel port (31) being connected through decoder (32) and driver (33) to relay (35) of sensor (7-14) circuit consisting of 12 V (D.C.) power supply (37), the output of the said sensor (7-14) circuit being connected to analog to digital port (34) through signal processor (36) and multi-channel input (38), the said analog to digital port (34) being interfaced to the analog input/output (24) of data station (1). In yet another embodiment of the present invention the temperature sensor (7) is a thermistor based bridge circuit, having range of 5 to 50° C, accuracy: ± 0.5° C, input voltage (39): 3 V D.C., output voltage (40): 0 to 100 mV D.C. after amplification through signal processor, reproducibility of ± 0.5° C, power consumption: 100 mw and shelf-life of over two years. In still another embodiment of the present invention the air velocity sensor (8) is a hot wire type Wheatstone bridge circuit, having range of 0.2 to 10 m/s, accuracy of ± 0.1 m/s, input voltage (41): 3 V (D.C.), output voltage (42): 0 to 10 mV after amplification through signal processor, reproducibility of ± 0.1% of the reading, power consumption: 100 mw and shelf-life of over two years. In still yet another embodiment of the present invention the machine status sensor (9) is a search coil type having range on/off, load/no-load, self-generated input voltage, output voltage (43): 0 to 500 mV A.C. after amplification through signal processor, power consumption: 100 mw and shelf-life of over five years. In a further embodiment of the present invention the methane sensor (10) is an electrode formed on an alumina ceramic tube with sintered bulk semiconductor composed mainly of tin oxide, and enclosing a heater coil, the sensor being housed in a non-metallic housing, the said sensor having range of 0 to 5 %, accuracy: ± 0.1 % of methane, input voltage (44): 5 V (D.C.), output voltage (45): 700 to 800 mV D.C. after amplification through signal processor, reproducibility: ± 0.1% of the reading, power consumption: 10 mW and shelf-life of over two years. In a still further embodiment of the present invention the carbon monoxide sensor (11) is a thin film electrode formed on a ceramic tube with sintered bulk semiconductor composed mainly of tin oxide having a pair of embedded wire electrodes and enclosing a heater coil, the sensor being housed in a non-metallic housing, the said sensor having range of 0 to 200 ppm, accuracy: 1 ppm, input voltage (46): 5 V (D.C.), output voltage (47): 700 to 800 mV D.C. after amplification through signal processor, reproducibility: ± 0.1% of the reading, power consumption: 20 mW and shelf-life of over two years. In a yet further embodiment of the present invention real-time monitoring is effected of carbon monoxide, temperature, air velocity, machine status and methane. In another embodiment of the present invention the system incorporates threshold limit alarm. In yet another embodiment of the present invention the system enables two-way communication. In still another embodiment of the present invention the computer (19) is of minimum specifications: hardware: RAM: 32 MB, CPU: Pentium I, HDD: 20 MB (free), colour monitor of resolution: 800 x 600 and 16 bit colour having one free serial communication port and software: operating system: Windows 98/NT/Me/XP/2000 and having software: Visual Studio 6.0. In still another embodiment of the present invention the computer (19) is provided with a software developed in higher level and assembly languages which enables collecting, processing and storing of data. In the present invention the main sub-system of the multi-channel intrinsically safe real-time environmental monitoring system for underground mines is the microprocessor based data station (1) which is kept in underground mine (2) and connected to a computer (19) at the surface through RS-422 link (5). The real time data is obtained from this device and logged onto the hard disk of the computer. These data can be displayed in the form of graphics including trends, bar charts in real time. Reports are generated from these data which are available as on-screen and hard copy printout can be obtained through printer (20). The data are also being stored in the hard disk at regular intervals. The underground data station (1) is placed inside the mine near the mine-face and connected to the computer (19). The microprocessor (1) is programmed to energize the relays (35) connected to a particular sensor with power supply (37) and signal processor (36), and thereby connecting the output of the sensor to the analog to digital converter channel (34). Similarly, data from any particular sensor is sent to analog to digital converter channel (34) for processing whenever required. The application software is developed in Visual Studio under Windows environment. The computer (19) at the control room runs the main program for collecting data from the underground data station (1). The data-station (1) continuously sends and receives data through the microprocessor (21) programmed in assembly language. It also sends requisite instruction to the underground data station (1) through the two-way communication link (5). The programme at the beginning selects the channels and the parameters to be monitored, and after proper handshaking is established with the data station (1), data starts coming to the computer screen channel-wise. Different windows can be opened to see the trend of data in different channels. Data is also stored channel-wise in a separate file in the hard disc. The stored data can further be analyzed for finding the average value, preferred parameter ratios and for other similar purposes. As the trends are more informative than absolute values, graphics software is utilized to represent and hard-copy graphs can be plotted against time. In a physical embodiment of the monitoring system of the present invention the specifications of the different units of the system are as follows: Data station (1) as shown in figure 2: microprocessor (21) - IC8085, memory (22) -8 KB RAM and ROM, digital input/output device (23) - IC8255, analog input/output (24) - Integrated circuit IC0800 (digital to analog converter) and IC0809 (analog to digital converter), serial communication port (25) - IC8251, keyboard/display interface (26) - IC8279, data bus (27) - 8 bit, power (28) - 5 V (D.C.), address bus (29) - 16 bit and control bus (30) - 8 bit. Multi-channel selector (4) as shown in figure 3: parallel port (31) - IC8255, decoder (32) - 3:8 IC74LS259, driver (33) - transistor 2N222, analog to digital port (34) -8/16 IC0809, relay (35) - 12 V/ 200 ohm, signal processor (36) - IC741, power supply (37) - 12 V (D.C.) and channel input (38) - 16 channels. The details of the sensors are: Temperature sensor (7): type - thermistor based bridge circuit, range - 5 to 50° C, accuracy - ± 0.5° C, shelf-life - beyond two years, input voltage (39) - 3 V (D.C.), output voltage (40) - 0 to 100 mV D.C. (after amplification through signal processor 0 to 5 V D.C.), reproducibility - ± 0.5° C, power consumption - 100 mW. The temperature sensor (7) as detailed in figure 4: resistance (R1) - 20 KQ rectangular port % W, R2 - 10 KQ metal film resistor Yt W, R3, R4 - 10 KQ ceramic disk type thermistor, R5 - 10 KQ rectangular pot, R6, R7 - 1 KQ carbon Y* W, R8 - 1 MQ rectangular pot, R9 - 1 MQ carbon 1/2 W, R10 - 20 KQ rectangular pot 1/2 W, R11 - 10 KQ wire wound pot 1 W, diodes (D1, D2) - IN4001, peak inverse voltage (PIV) 400V/100mA, capacitor (C1)- 0.1 ufd/16V, IC1-IC741. Air velocity sensor (8): type - hot wire type (Wheatstone Bridge circuit), range - 0.2 to 10 m/s, accuracy - ± 0.1 m/s, shelf-life - beyond two years, input voltage (41) - 3 V (D.C.), output voltage (42) - 0 to 10 mV (after amplification through signal processor 0 to 5 V D.C), reproducibility - ± 0.1% of the reading, power consumption -100mW. Air velocity sensor (8) as detailed in figure 5: R12 - 500 Q rectangular pot % W, R13 - 100 Q metal film resistor Yz W, R14, R15 - 20 Q sensing and compensating elements made up of platinum wire 47 standard wire gauge (SWG), respectively, R16 - 10 KQ rectangular pot, R17, R18 - 2 KQ carbon 1/2 W, R19 - 1 MQ carbon 1/2 W, R20 - 2 MQ rectangular pot, R21 - 20 KQ rectangular pot 1/4 W, R22 - 10 KQ wire wound pot 1 W, D3, D4 - IN 4001, PIV 400 V/100 mA, C2 - 0.1 ufd/16 V, IC2 -IC741. Machine status sensor (9): type - search coil type, range - on/off, load/no-load, shelf-life - beyond five years, input voltage - nil (self-generation), output voltage (43) - 0 to 500 mV A.C. (after amplification through signal processor 0 to 5 V D.C.), power consumption - 100 mW. Machine status sensor (9) as detailed in figure 6: rod (S1) - over a ferite core of 10 cm length nearly 10,000 number of turns of copper wire 42 SWG are wound, induction of coil is 330 mH, resistance of coil is 58 0, R23 -10 KQ rectangular pot, R24 - 1 MQ carbon 1/2 W, R25 - 2 MQ rectangular pot, R26 - 20 KQ rectangular pot 1/2 W , R27 - 10 KQ wire wound pot 1 W, D5 - IN4001 PIV 400 V/100 mA, C3 -0.1 ufd/16Vand IC3-IC741. Methane sensor (10): type - semiconductor based (This sensor is a sintered bulk semiconductor composed mainly of tin oxide. The semiconductor material and electrode are formed on an alumina ceramic tube. A heater coil made of 60 microns diameter is located in the ceramic tube. The sensor components are housed inside a non-metallic housing), range - 0 to 5 %, accuracy - ± 0.1 % of methane, shelf-life -beyond two years, input voltage (44) - 5 V (D.C.), output voltage (45) - 700 to 800 mV D.C. (after amplification through signal processor 1 to 3 V D.C.), reproducibility -± 0.1% of the reading, power consumption - 10 mW. Methane sensor (10) as detailed in figure 7: R28 - 60 Q, R29 - 30 KQ, R34 - 20 KQ 1/2 W, R31 - 2 KQ, R32 - 1 KQ, R33 - 100 KQ, R34 - 20 KQ, R35 - 10 KQ, all resistances 1/2W, C4-0.01 ufd, transistor(Q1J-TIP122, IC4-IC741. Carbon monoxide sensor (11): type - semiconductor based wherein the core of the sensor is thin film based semiconductor. Tin oxide is main material of the sensor element. A pair of wire electrodes is embedded in the sintered material. A heater coil made of 60 micron diameter is located in the ceramic tube. The sensor components are housed in a non-metallic housing), range - 0 to 200 ppm, accuracy - 1 ppm, self-life - beyond two year, input voltage (46) - 5 V (D.C.), output voltage (47) - 700 to 800 mV D.C. (after amplification through signal processor 1 to 2 V D.C.), reproducibility - ± 0.1% of the reading, power consumption - 20 mW. Carbon monoxide sensor (11) as detailed in figure 8: R36 - 25 Q, R37 - 45 KQ, R38 - 10 KQ, R39 - 1 KQ, R40 - 1 KQ, R41 - 1 MQ, R42 - 20 KQ, R43 - 10 KQ, all resistances 1/2 W, C5 - 0.01 ufd, IC5-OP27 and Q2-TIP122. Equivalent components can also be used wherever required. The novel features of the present invention have been realized by the non-obvious inventive steps of integrating the various sub-systems and components to function as a multi-channel intrinsically safe real-time environmental monitoring system for underground mines. The novelty and inventive steps of the present invention with respect to the prior art are: (i) provision of extendable multi-channel facility which enables monitoring of various parameters at any number of locations in a big underground mine and consumes less power by use of same signal processor for all the similar sensors; (ii) capable of real-time monitoring of carbon monoxide, which is an important parameter for most of the underground mines, in addition to measurement of temperature, air velocity, machine status and methane; (iii) development of semiconductor based methane and carbon monoxide sensors which consume less power and give higher sensivity compared to the hitherto known system; (iv) capable of simultaneous visual interpretation of trend of monitored data by a high quality graphic software and imparts warning signal when particular parameter crosses the respective threshold limit; and (v) provision of two-way communication, which is very much essential for taking up appropriate control measures whenever required from the surface. Installation of the monitoring system of the present invention in an underground mine should be done as follows: The microprocessor based data station (1) should be placed at a safe and dry place in the underground. Systematic lay down of cables (5 and 6) is very essential for proper data transmission. The cables (5 and 6) are multi pair twisted and armored (0.5 mm diameter or thicker copper conductor), having negligible inductance and capacitance. The cables (5 and 6) should be laid with least twists and kinks and fastened through clamps on the hard walls of side galleries. At every fifty meters clamps are to be fixed so that the cables remain stretched. A minimum distance of one meter should be maintained between the mine main power cable and the data cables (5 and 6) to avoid electromagnetic interferences. The sensor boxes (7-14) are to be fixed on the side-wall of the gallery of the mine. If possible the gas sensors (10-11) should preferably be hung from the roof of the gallery for optimum result. The complete software developed by us is menu driven, self-explanatory and does not require any prior sophisticated computer training. The software is designed to work in two modes, namely, on-line (real-time) and off-line. In on-line (real-time) mode the software automatically detects the connection with data station and configures itself appropriately for future communication and request for data of different sensors is sent to the data-station. The data station serves the request by sending the data of the required sensor and then computer retrieves the instantaneous data from the serial communication ports as per the connection. Finally the data is displayed numerically or graphically and automatically saved in a database file, the name of which corresponds to the system date. In off-line mode, one can display the pre-recorded data by simply selecting the file of the required date. Different windows could be opened for viewing graphical simulation of the data of different channels. Both operating modes of the software support hard copy printing of data such as numerical or graphical as required. Various statistical analysis operations like maximum, minimum, average, moving average, standard deviation etc. are also incorporated. There are alarms and warning messages when a data crosses its safe limit in the on-line mode. For administrative works like changing channel configurations, enough security has been maintained through the use of passwords. The following examples are given by way of illustration of the multi-channel intrinsically safe real-time environmental monitoring system for underground mines and therefore should not be construed to limit the scope of the present invention. EXAMPLE-1 The monitoring system of the present invention was first installed at Jhanjra 1&2 incline, being worked by longwall method of working, of Eastern Coalfields Limited, Sanctoria, Burdwan, West Bengal, India, with all the accessories. The system was operated on an experimental basis for over six months. Different sensors were located at various working locations in the underground mines. The parameters monitored during the period were temperature, air velocity, machine status, methane concentration and carbon monoxide concentration with the range of 26-35°C, 0.5-2.9 m/s, ON - OFF, 0-1.1 %, 0-12 ppm, respectively. The system successfully provided warning signals as well as visual interpretation of simultaneous graphs for particular sensor when temperature and air velocity crossed the threshold limit of 30°C and 1.1 m/s, respectively. Subsequently, corrective measures were implemented by the management to bring the respective parameter within the threshold limit. The total system was successfully operated in the mine and managed from the surface control room through two-way communication facility. EXAMPLE-2 The monitoring system of the present invention was installed for a second trial in a mine worked by Board and Pillar method of mining. The monitoring system was installed and operated in the Sudamdih shaft mine of Bharat Coking Coal Limited, Dhanbad, Jharkhand, India, on an experimental basis for a period of around six months. All the five category of sensors were installed at various working locations in the mine. The range of parameters were 27-36°C, 0.6-3.1 m/s, ON - OFF, 0 - 0.9 % and 0-15 ppm for temperature, air velocity, machine status, methane concentration and carbon monoxide concentration, respectively. The system provided audio-visual warning signal for a particular sensor when temperature and air velocity crossed the pre-set threshold value of 30°C and 1.1 m/s, respectively. All the additional features of the system were successfully operated in the mine through out the field trial period. The system indicated an excellent representation data of the underground environmental conditions during the reopening of the sealed off area by the mine management. This enabled the mine management to assess the environmental conditions and to take the necessary precautionary measures as and when required. The total system was successfully operated in the mine and managed from the surface control room through two-way communication facility.- The total monitoring system of the present invention essentially enabled the smooth functioning of the underground mining operations. This system also helped the mine management to enhance the safety and productivity at different underground working environments and mining methods. Provision of multi-channel facility helped in monitoring of various parameters at any number of locations in the big underground mines and consumed less power by using same signal processor for all the similar sensors. The facility for real-time continuous monitoring of carbon monoxide enabled the mine management to reduce the workers' exposure level and duration to the noxious gas by taking appropriate measures at the earliest. The development of semiconductor based methane and carbon monoxide sensors consumed less power and provided higher sensivity, which helped to reduce the cost of operation and to provide accurate result. All the data were analysed by the mine management from the surface control room through simultaneous visual interpretation of trend of monitored data by a high quality graphic software. The system also imparted audio-visual warning signal when any particular parameter crossed the respective threshold limit which helped the mine management to take immediate corrective measures and thus avoid occurrence of a catastrophe. The provision of two-way communication helped the mine management to take up appropriate control measures whenever required from the surface and reduced the delay in the process. Therefore, it is conclusively shown that the novel features enabled by the inventive steps of the multi-channel intrinsically safe real-time environmental monitoring system for underground mines of the present invention essentially proved useful for the mine management for better safety and enhancement of productivity. The main advantages of the monitoring system of the present invention are: 1. The system can monitor various environmental parameters in any number of locations in a big underground mine. 2. The system requires minimum consumption of power with the help of low power semiconductor based methane and carbon monoxide sensors, and microprocessor based switching technique. 3. The system having two-way communication, instruction can be sent to the data station for any immediate control action required in the underground in case of emergency. 4. The system provides real-time continuous monitoring of environmental parameters with alert/alarm system which helps in detecting the slow deterioration in the ventilation system/environmental condition and detect heating or increase in methane or carbon monoxide concentration much before an occurrence of an accident or catastrophe. 5. The system provides increased productivity and profitability. 6. The system reduces the response time and minimizes dependence on human errors. 7. The system monitors the unexpected and sudden changes in the environmental parameters and thus enables detection of fires. 8. The system monitors the trend of the parameters and helps easy diagnosis and pin-pointing of the problem and timely corrective action can be taken. 9. The system provides indication that the ventilation system is functioning as per design and guidelines laid down. It can also be utilized for proper ventilation planning of the mine. 10. The system provides indication of he production rate or running time of a particular operation through the machine status sensor of the system. We claim: 1. A multi-channel intrinsically safe real-time monitoring device for underground mines, which comprises electronic hardware located in an underground mine (2) essentially consisting of a microprocessor based data station (1) connected respectively to an intrinsically safe 5 V D.C. power supply (3), data communication link (5) characterized in that it is capable of transmitting data and providing two-way communication, and a multi-channel selector (4); the said multi-channel selector (4) being connected to outputs (6) of a plurality of sensors such as temperature (7), air velocity (8), machine status (9), methane (10), carbon monoxide (11) and other optional sensors (12-14); the sensors being powered by intrinsically safe power supply (15) through 5 V D.C. connector (16) and sensor signal processors being connected through 12 V D.C. intrinsically safe power cable (17); the said data station (1) being connected through the said data communication link (5) to a computer (19) and a printer (20) on the surface (18) of the said underground mine (2). 2. A device as claimed in claim 1, wherein the data station (1) capable of receiving and transmitting data consists of: microprocessor (21), memory (22), digital input/output device (23), analog input/output (24), serial communication port (25), keyboard/display interface (26), data bus (27), 5 V D.C. power supply (28), address bus (29), and control bus (30) duly interconnected to function as a data station; the said analog input/output (24) being connected through the multi-channel selector (4) to sensors (7-14) and the said serial communication port (25) being connected through the data communication link (5) to the computer (19). 3. A device as claimed in claims 1-2, wherein the multi-channel selector (4) capable of receiving and transmitting data from the sensors (7-14), comprises: parallel port (31) interfaced to data station (1), the said parallel port (31) being connected through decoder (32) and driver (33) to relay (35) of sensor (7-14) circuit consisting of 12 V (D.C.) power supply (37), the output of the said sensor (7-14) circuit being connected to analog to digital port (34) through signal processor (36) and multichannel input (38), the said analog to digital port (34) being interfaced to the analog input/output (24) of data station (1). 4. A device as claimed in claims 1-3, wherein the temperature sensor (7) is a thermistor based bridge circuit, having range of 5 to 50° C, accuracy: + 0.5° C, input voltage (39): 3 V D.C., output voltage (40): 0 to 100 mV D.C. after amplification through signal processor, reproducibility of ± 0.5° C, power consumption: 100 mw and shelf-life of over two years. 5. A device as claimed in claims 1-4, wherein the air velocity sensor (8) is a hot wire type Wheatstone bridge circuit, having range of 0.2 to 10 m/s, accuracy of ±0.1 m/s, input voltage (41): 3 V (D.C), output voltage (42): 0 to 10 mV after amplification through signal processor, reproducibility of ± 0.1% of the reading, power consumption: 100 mw and shelf-life of over two years. 6. A device as claimed in claims 1-5, wherein the machine status sensor (9) is a search coil type having range on/off, load/no-load, self-generated input voltage, output voltage (43): 0 to 500 mV A.C. after amplification through signal processor, power consumption: 100 mw and shelf-life of over five years. 7. A device as claimed in claims 1-6, wherein the methane sensor (10) is an electrode formed on an alumina ceramic tube with sintered bulk semiconductor composed mainly of tin oxide, and enclosing a heater coil, the sensor being housed in a non-metallic housing, the said sensor having range of 0 to 5 %, accuracy: ± 0.1 % of methane, input voltage (44): 5 V (D.C), output voltage (45): 700 to 800 mV D.C. after amplification through signal processor, reproducibility: ± 0.1% of the reading, power consumption: 10 mW and shelf-life of over two years. 8. A device as claimed in claims 1-7, wherein the carbon monoxide sensor (11) is a thin film electrode formed on a ceramic tube with sintered bulk semiconductor composed mainly of tin oxide having a pair of embedded wire electrodes and enclosing a heater coil, the sensor being housed in a non-metallic housing, the said sensor having range of 0 to 200 ppm, accuracy: 1 ppm, input voltage (46): 5 V (D.C), output voltage (47): 700 to 800 mV D.C. after amplification through signal processor, reproducibility: ± 0.1% of the reading, power consumption: 20 mW and shelf-life of over two years. 9. A device as claimed in claims 1-8, wherein real-time monitoring of carbon monoxide, temperature, air velocity, machine status and methane is enabled. 10. A device as claimed in claims 1-9, wherein the system incorporates threshold limit alarm. 11. A device as claimed in claims 1-10, wherein the system enables two-way communication. 12. A multi-channel intrinsically safe real-time monitoring device for underground mines, substantially as herein described with reference to the examples and drawings accompanying this specification.

Documents:

149-DEL-2003-Abstract-(04-09-2008).pdf

149-del-2003-abstract.pdf

149-del-2003-claims.pdf

149-DEL-2003-Correspondence-Others-(04-09-2008).pdf

149-del-2003-correspondence-others.pdf

149-del-2003-correspondence-po.pdf

149-del-2003-description (complete).pdf

149-del-2003-drawings.pdf

149-DEL-2003-Form-1-(04-09-2008).pdf

149-del-2003-form-1.pdf

149-del-2003-form-18.pdf

149-DEL-2003-Form-2-(04-09-2008).pdf

149-del-2003-form-2.pdf

149-DEL-2003-Form-3-(04-09-2008).pdf

149-del-2003-form-3.pdf