Title of Invention

MICROPROCESSOR BASED SOLID STATE CONTROL SYSTEM FOR HAULERS IN COAL MINE

Abstract

A microprocessor based solid state control system hauler in a coal mine with a motor, gearbox and a ropedrum the said system comprising: - a housing, - a changeover selector unit disposed within the said housing, operable externally, and positioned in the top portion of the said housing for selecting the changeover from the conventional drive system to a microprocessor based control system, - a microprocessor disposed within said housing in the bottom portion, - plurality of display unit disposed on the surface of the said housing for viewing the coal tub hauling conditions, - plurality of the input signals from the input means operatively connected to the said microprocessor for feeding a set of user instructions through programmable microprocessor, and - plurality of the output signals generated by the microprocessor for operatively feeding corresponding control signals to the motor, - wherein plurality of the input means includes atleast one local program keypad and atleast one remote application keypad wired to the controller system, - wherein the local program keypad is in communication receive user signals from the keys and to provide a predictive execution model by means of said processor, - wherein the remote application keypad is in communication receive the user signals from the keys and to feed corresponding control signals to the motor in response to the

Full Text

This invention relates to a Microprocessor based Solid State Control system for Haulers in coal mines which is adapted and including change over mechanism to operate both in conventional mode and microprocessor mode. Prior Art In the mining Industry, the coal tubs are hauled up from the working place to the surface by using haulers. The conventional system is generally prevalent in the mining industries is a non-linear resistance electro-mechanical controller devices. A conventional system as stated in Fig 3 comprising of a forward and reverse unit, drum control unit, resistance unit and brush gear unit of the 3- Phase slip ring Induction motor. In the conventional system, it works on non-linear resistive electro-mechanical control system. Therefore the power consumption is very high. Besides, the components are wired and involves high maintenance due to non-linearity, more operators physical stress and more moving parts, poor efficiency and improper resistance contacts are the difficulties. Description Of Various Units Of Conventional System Forward and Reverse Selector Unit This is an electromechanical unit. This unit would be used for changing the speed direction of 3- Phase slip ring Induction motor. Therefore the hauler would be operated either Forward or Reverse direction. Drum Control Unit Drum control unit was interfaced to the Resistance and F&R Unit. This unit used for selecting resistance of resistance box for controlling the speed of the 3-Phase slip ring Induction motor. Resistance Unit The conventional system works on resistance controls. Therefore, this unit plays vital role in the operation of the system. This unit works with the combination of drum control unit. The speed of the 3- Phase slip ring induction motor depends on this unit. Brush gear Unit This unit would helps 3- Phase slip ring Induction motor for getting desired torque. This was interfaced to the resistance unit and 3-Phase slip ring induction motor. Object Of The Invention :- It is the first object of the invention to develop Microprocessor based control system which can be fixed and adopted to work in a parallel with conventional system or independently. The main object of the invention is to replace the expensive 3 phase slip ring Induction motor with brush gear unit to squirrel cage induction motor. The object of the invention is to design a new system which will overcome the demerits of known art and which also include switchover back to conventional process if desired, so as to make the invention most adaptable to field condition at all times. It is further object of the invention to eliminate the problematic conventional electro-mechanical units i.e., forward and reverse units, drum control unit, resistance unit and 3-phase slip ring induction motor with brush gear unit of the conventional hauling system. It is another object of the invention to develop a system with reduced power consumption where in the current conventional system is power consuming and involves high maintenance with low efficiency and instead replace with a low power consuming MBSC system operable via set of keypads which controls desired torque and speed of the motor. It is another object of the invention to incorporate a selection unit wherein hauling system is workable both, in conventional mode or in microprocessor mode as and when desired. Brief Description of The Invention :- The system as per the invention is a microprocessor based controller for a squirrel cage induction motor, which is so interfaced through the control panel to the conventional system, to enable the operation of motor by choice either by conventional system or through microprocessor. The system as per the invention is a microprocessor based solid state control system housed in a sheet metal housing. The housing has three portions divided such as to comprise:- 1. Top - mode selector portion. 2. Centre - MBSC control system portion. 3. Lower - motor control system portion. The wiring and cabling is done such as desired to run the system in the MBSC mode or the Conventional mode. The system has the MBSC mode and conventional mode wherein the user has an option to make the choice. (i) The top mode selector is a changeover unit which allows and enables the user to changeover from conventional mode to MBSC mode or vice versa. (ii) The second component of the panel which is a MBSC control panel consists of a microprocessor, two keypads and display. The microprocessor controls the operation of the hauling system. The output of the MBSC system will be directly applied to the Induction motor via two sets of keypads. First one being a 'Program key pad' and second being an 'Application key pad'. The program key pads are operable only by authorised user. It is fixed in the MBSC system and for setting vital parameter limits e.g., speed, current, voltage, frequency, overload protection totaling to nearly 46 parameters. The second key pad known as ' application key pad ' is wired to the MBSC and can be operated remotely. The second key pad only has four keys-start, stop, speed and direction frequently used by the operator. The first key pad is under the supervision and control of the authorized supervisor and the second key pad is operated by the layman operator. Description of The Invention :- This invention is related to hauling of coal tubs in mines more specifically it is a non-linear resistance conventional system. Therefore the conventional system breaks down very frequently and consumes very high power, thus it hampers the production and safety. Accordingly it is a principal object of the invention to provide a linear frequency control implemented with microprocessor based solid state controller within a covered housing positioned away at a safe distance and clean environment, controllable both at point of hauling and at housing end suitably. The present invention is not limited to any specific size and dimension and can be of any suitable size. While various changes can be incorporated in the detail construction, it is understood that such changes will be within the spirit and scope of the present invention as is defined by the claims. The mode selector changeover unit enables the user to select one of the two modes either MBSC mode or conventional mode to control the motor and thereby the haulage operation. The incoming voltage enters into the air circuit breaker. The reduction gear box interfaced to the squirrel cage motor shaft reduces the motor speed to 30:1 and drives the rope drum. The coal tub connected to the one end of the rope is transported from underground to surface. In the conventional mode, the control is manual, whereas in the MBSC mode, the output is directly interfaced to the squirrel cage Induction motor. Further in the MBSC mode, the system control program is controlled from the main key pad attached to the system. The second remote key pad enables the operator to operate the simple On/Off/speed/direction only. The description and operation of MBSC system is as follows: Three phase AC motors are comprised of two major components, the stator and the rotor. The stator is a set of three electrical windings held stationary in the motor housing. The rotor is a metal cylinder, fixed to the motor drive shaft, which rotates within the stator. The arrangement of the stator coils and the presence of three-phase AC voltage give rise to a rotating magnetic field, which drives the rotor. The speed at which the magnetic field rotates is known as the synchronous speed of the motor. Synchronous speed is a function of the frequency at which the voltage is alternating and the number of poles in the stator windings. The strength of the magnetic field in the gap between the rotor and stator is proportional to the amplitude of the voltage at a given frequency. The output torque capability of the motor is, therefore, a function of the applied voltage amplitude at a given frequency. When operated below (rated) speed, AC motors run in the range of constant torque. The microprocessor - based system is interfaced to the AC three phase induction motor as shown in Fig (1).further is interfaced with reduction gear box and rope drum. Incoming AC line voltage is converted to a pulsating DC voltage by the input diode bridge of the MBSC system. The DC voltage is supplied to filter capacitor bank through a charging circuit, which limits inrush current to the capacitors during power-up. The pulsating DC voltage is filtered by the capacitor, which reduces the ripple level. The filtered DC voltage enters the control section of the system, composed of six output intelligent/insulated gate bi-polar transistors (IGBTs), which make up the three output legs of the system. Each leg has one intelligent/IGBT connected to the positive bus voltage and one connected to the negative bus voltage. Alternatively switching on each leg, the intelligent/IGBT produces an alternating voltage on each of the corresponding motor windings. By switching each output intelligent/IGBT at a very high frequency (known as the carrier frequency) for varying time intervals, the system is able to produce smooth, three phase, sinusoidal output current wave which optimizes motor performances. Therefore, the power consumption is reduced by 20-40% and improved the hauler efficiency by eliminating many conventional problematic power consuming modules of conventional system. The control module consists of 16-bit microprocessor, keypad and display. System programming is accomplished via the keypad or the serial communication port. During operation the system can be controlled via the keypad, by control devices wired to the control terminal strip. The power board of MBSC system contains the control and protection circuits, which govern the six, output IGBTs. The power board also contains a charging circuit for the filter capacitors, a motor current feedback circuit, a voltage feedback circuit, and a fault signal circuit. It has several built in protection circuits. These include phase-to-phase and phase-to-ground short circuit protection; high and low line voltage protection, protection against excessive ambient temperature, and protection against continuous excessive output current. Activation of any of these circuits will cause the drive and thereby haulage system to shut down in a fault condition. A microprocessor based solid state control system in a parallel arrangement for a changeover from a conventional drive system of coal tubs hauling in a coal mine with a motor, gearbox and a ropedrum comprising of: - a housing, - a changeover selector unit disposed within the said housing, operable externally, and positioned in the top portion of the said housing for selecting the changeover from the conventional drive system to a microprocessor based controller system, - a microprocessor disposed within said housing in the bottom portion, - plurality of display unit disposed on the surface of the said housing for viewing the coal tub hauling conditions, - plurality of the input signals from the input means operatively connected to the said microprocessor for feeding a set of user instructions through said programmable microprocessor, and - plurality of the output signals generated by the microprocessor for operatively feeding corresponding control signals to the motor, wherein plurality of the input means includes atleast one local program keypad and atleast one remote application keypad wired to the controller system, - wherein the local program keypad is in communication receive user signals from the keys and to provide a predictive execution model by means of said processor, wherein the remote application keypad is in communication receive the user signal from the keys and to feed corresponding control signals to the motor in response to the input signals. The said processor of a control system diode Bridge Rectification means for rectification of incoming AC power, filtration means for filtering and removing ripples fromjhe incoming AC power, control Module to receive the filtered DC and which further includes 16 bit microprocessor, first and second key pads alongwith display, and power Module includes control and protection circuits within, wherein said rectification means includes Diode bridge to rectify incoming AC line voltage to pulsating DC voltage which is the source to filtration means, wherein said filtration means include capacitors to filter the pulsating DC voltage and reduce the ripple levels, wherein said Control module includes 16-bit microprocessor which further includes six output intelligent/ insulated gate bi-polar transistors (IGBTs) which make up the three output legs of the system, each leg has one intelligent/IGBT connected to the positive bus voltage and one connected to negative bus voltage, alternatively switching on each leg, the IGBT produces an alternating voltage on each of the corresponding motor windings, by switching each output IGBT at high carrier frequency at varying time intervals, it produces smooth, three phase, sinusoidal output current wave to optimize motor performance, wherein the said first key pad of the control module is the program key pad fixed on the control panel and for programming system parameters by the system programmer, wherein the second key pad of the control module is the application key pad wired to processor control panel and operable remotely for a keys i.e., Start, Stop, Speed and direction only by the operator, wherein display is interfaced to the processor to display the selection choices, alarm indications and to selecting the operating parameters, and wherein the power module includes control and protection circuits, which govern the output IGBTs alongwith charging circuit for filter capacitors, motor current feedback circuit, a voltage feedback circuit and fault signal circuit, the protection circuits include phase-to-phase and phase-to-ground short circuit protection, high and low line voltage protection, protection against excessive ambient temperature and protection against continuous excessive output current. The said changeover selector switch is mounted within the housing and a panel having operation button/handle knobs by which a user activates the said selector switch, and comprising of : first Switch comprising first and second fixed contacts, and a fixed first common contact located between the first and second fixed contacts and the first movable contact strip means attached to first common contact for alternatively touching the first and second contacts and first common contact adapted to receive line supply from ACB, second Switch comprising third and fourth contacts and a fixed second common contact located between third and fourth fixed contacts, and a second movable contact strip means attached to second common contact for alternatively touching the third and fourth contacts and second common contact adapted to receive supply from the processor, operating means comprising a handle for activating the first and second movable contact strip means concurrently in order to connect first and third fixed contacts to first and second common contacts respectively or connect the second and fourth fixed contacts to first and second common contacts respectively, interlocking switch for activating processor control circuit or conventional control circuit in order to achieve processor mode and conventional mode, wherein when second fixed contact is made adaptable to be connected to conventional controller system, then concurrently fourth fixed contact is made adaptable to receive output from conventional control system and also to connect to motor terminals for supplying via conventional controller system, first fixed contact is made adaptable to input terminals of processor control current, second common contact is made adaptable to be connected to output terminals of processor, and third fixed contact is made adaptable to be connected to motor terminals for supply via processor controller system, and further alternatively and wherein when first fixed contact is made adaptable to be connected to conventional control system then concurrently third fixed contact is made adaptable to receive output from conventional control system and also to connect to motor terminals for supply via conventional controller system, second fixed contact is made adaptable to be connected to input terminals of processor control current, second common contact is made adaptable to be connected to output terminals of processor, and fourth fixed contact is made adaptable to be connected to motor terminals for supply via processor controller system. The said housing is made of sheet metal and comprising :- a top portion; a central portion and a bottom portion, wherein the top portion is configured to hold the changeover selector unit, wherein the central portion is configured to hold processor, wherein the bottom portion is configured to hold the motor receptacle, wherein the top portion is further specifically configured to receive power supply from ACB of conventional drive control system to feed the changeover selector unit, wherein the top portion further is specifically configured to feed supply power back to conventional drive control system via changeover selector unit, wherein the bottom portion is further specifically configured to receive supply from conventional drive control system to feed directly to the motor terminals, and wherein necessary electrical coupling and mechanical connections are provided between top, central and bottom portion of the housing. The MBSC drive system thus provides solid state Controller system and Conventional Controller system to control speed of a motor. The MBSC drive Control System control panel, thus provides a changeover between solid state controller MBSC system and conventional control system by activating a single mode selection switch. The MBSC drive system has a dynamically updated displays. The MBSC drive system has a local key pad and remote key pad which provide safe and reliable operations. The MBSC control panel has the below mentioned specification : Control panel being used for operating system in two modes. They are 1) conventional mode and 2) MBSC mode. The block diagram of the control panel is in Fig 6. This facility is provided for keeping one of the systems as a stand by. Therefore, the hauler system is available for transportation of coal tubs is continuous, irrespective of breakdowns. Moreover, this new technology is introduced recently. If the operator is not comfortable with this system, he can choose conventional system for hauling the load. As per the invention the mode can be changed by adopting following procedure with the selection mode switch : • First switch means of changeover switch of power section to be in B position as reflected in fig 6. • Second switch means of change over switch of motor section to be in B position as reflected in fig 6. Therefore, the switch positions should be in the same line and direction. Now the operator will be working with conventional system MBSC mode In this mode microprocessor would control the haulage system. This method would be selected by adapting the following procedure • First switch means of changeover switch of power section to be in A position as reflected in fig 6. • Second switch means of change over switch of motor section to be in A position as reflected in fig 6. Therefore, the switch position and direction of the motor and power section of control panel should be in bottom vertical. Now the operator will work with new (MBSC) system In the changeover, first switch means is positioned and followed by the positioning of second switch means at all times. While changing over the method of operation switch off the system power and select the desired method. Remote control key pad is interfaced to the system through a control box and it is used for following operations and block diagram as in Fig 7. • START the motor - Push Button (Green Color) • STOP the motor - Push Button (Red Color) • FWD/REV change of direction - Switch knob (Block color) • Speed control - Potentiometer The purpose is the remote but limited operation by the operator. The aforesaid four switch buttons are frequently used or complete haulage operation depends on four push button. Therefore these push buttons are separated for operator to easy operation. Interlock is provided at the outgoing changeover switch of the system by control panel, such that the system will switch off if the changeover switch handle is operated. SYSTEM SPECIFICATIONS AND OPERATING ENVIRONMENT :- Ambient temperature - -10° to 55° C Ambient Humidity - Less than 95% (non-condensable) Input Line Voltage - 240/120 Vac, 240/200 Vac, 480/400 Vac and 590/480 Vac Input Voltage tolerance - +10%,-15% Input frequency tolerance - 8 to 62 Hz Output waveform - Sine coded PWM Output frequency - 0-120 Hz, Optional up to 60 Hz Carrier frequency - 2.5 KHz to 14 KHz (5 KHz typically) Efficiency - >97% throughout speed range Power factory - >0.96 Control voltage - 15VDC CONTROL PANEL SEPCIFICATION :- The specification of control panel are as follows :- Base Channel ISMC 72x40 mm Inter Connection bus bars 25x6 mm copper used with the panel Change over switch 125/100A control & switchgear Interconnection with motor 70 sqmm of 3C armoured copper cables GlandsDouble compression Flame proof cables Lugs Jainsons makes Keyboards programmable and applications Description Of Invention With Drawings :- Fig. 1 illustrates the block diagram of MBSC based haulage system. Fig. 2 illustrates the lock diagram showing various modules of MBSC system as envisaged in the invention. Fig. 3 illustrates the conventional Haulage system, with the component elements making up the control system of the motor. Fig, illustrates the block diagram of four modules that comprise the invention of MBSC system. Fig. 5iUustrates the housing construction, with the electrical connections and terminals generally marked therein, with the shape and configuration of the housing. Fig. 6llustrates the block diagram of the remote key pad as per the invention. Fig. 7illustrates the graph between current and Speed of slip ring induction motor with Microprocessor Based Solid State Control (MBSC) System. Fig. 8illustrates the current Vs Speed graph of conventional haulage system Practical Investigation Of The Invention Shown In The Graph :- Fig.8 shows the current Vs Speed graph of conventional haulage system, As per the graph the conventional system takes 60 amps current at a speed of 0 rpm initially. The current was varied from 60 amps to 40 amps at a speed varying from zero to 125 RPM. Further the current was varying with speed up to 60 amps at full speed of 750 rpm. The relation is a non linear and is very poor control. Therefore, conventional system requires 60 amps current initially and excess current was wasted as a heat. At zero speed or at full speed the current drawn is maximum (60 amp). Fig. 7 shows the graph between current and speed of slip ring induction motor with Microprocessor Based Solid State Control (MBSC) system. As per the graph the MBSC system took zero Amps current at zero speed initially. The current was varying from zero to 60 Amps with the speed of 0 to 750 RPM. The current was linearly varying from zero to 60 Amps with speed. The relation was linear and is a good control over the speed. Therefore, MBSC system requires zero Amps current initially and the power saving was more initially and less in later stages. The sudden small jump at 35 Amp was due to non-uniformity of haulage road gradient. The behavior of the hauler with MBSC system was linear. Therefore better control achieved and efficiency of the hauler was improved. Advantages Of The Invention :- Following components of the conventional haulage system are eliminated by introducing the MBSC system • Drum Controller unit • Series of resistance units • Forward and Reverse control unit • Slip ring motor can be replaced with squirrel cage induction motor Internal cables required for connecting drum controller, F & R switch, resistance and slip ring brush gear unit of the motor. Brush gear unit of the motor (slip rings, brushes and brush holders). Humming sound of the motor is eliminated. Maintenance of the hauler electrical system Physical stress and strain of the hauler driver Consumption of the electrical spares for maintenance/repair The operational defects and the down time of the haulage system The moving parts of the electrical controls Heat generation and sparks Tampering of control system due to electronic password protection Mechanical jamming of the conventional haulage system Frequent fluctuations in flow of voltage and current. Shock/impact loads on mechanical components including (coupling bolts, couplings, keys, Gearbox, Rope socket, D-links, pins and shackles) frequent derailment of tubs. WE CLAIM:- 1. A microprocessor based solid state control system hauler in a coal mine with a motor, gearbox and a ropedrum the said system comprising: - a housing, - a changeover selector unit disposed within the said housing, operable externally, and positioned in the top portion of the said housing for selecting the changeover from the conventional drive system to a microprocessor based control system, - a microprocessor disposed within said housing in the bottom portion, - plurality of display unit disposed on the surface of the said housing for viewing the coal tub hauling conditions, - plurality of the input signals from the input means operatively connected to the said microprocessor for feeding a set of user instructions through programmable microprocessor, and - plurality of the output signals generated by the microprocessor for operatively feeding corresponding control signals to the motor, - wherein plurality of the input means includes atleast one local program keypad and atleast one remote application keypad wired to the controller system, - wherein the local program keypad is in communication receive user signals from the keys and to provide a predictive execution model by means of said processor, - wherein the remote application keypad is in communication receive the user signals from the keys and to feed corresponding control signals to the motor in response to the input signals. 2. A control system as claimed in claim 1, wherein the said changeover selector switch is mounted within the housing and a panel having operation button/handle knobs by which a user activates the said selector switch, comprising: - first Switch comprising first and second fixed contacts, and a fixed first common contact located between the first and second fixed contacts and the first movable contact strip means attached to first common contact for alternatively touching the first and second contacts and first common contact adapted to receive line supply from ACB, - second Switch comprising third and fourth contacts and a fixed second common contact located between third and fourth fixed contacts, and a second movable contact strip means attached to second common contact for alternatively touching the third and fourth contacts and second common contact adapted to receive supply from the processor, - operating switch comprising a handle for activating the first and second movable contact strip means concurrently in order to connect first and third fixed contacts to first and second common contacts respectively or connect the second and fourth fixed contacts to first and second common contacts respectively, - interlocking switch for activating processor control circuit or conventional control circuit in order to achieve processor mode and conventional mode, wherein when second fixed contact is made adaptable to be connected to conventional controller system, then concurrently fourth fixed contact is made adaptable to receive output from conventional control system and also to connect to motor terminals for supplying via conventional controller system, first fixed contact is made adaptable to input terminals of processor control current, second common contact is made adaptable to be connected to output terminals of processor, and third fixed contact is made adaptable to be connected to motor terminals for supply via processor controller system, and further alternatively and wherein when first fixed contact is made adaptable to be connected to conventional control system then concurrently third fixed contact is made adaptable to receive output from conventional control system and also to connect to motor terminals for supply via conventional controller system, second fixed contact is made adaptable to be connected to input terminals of processor controller current, second common contact is made adaptable to be connected to output terminals of processor, and fourth fixed contact is made adaptable to be connected to motor terminals for supply via processor controller system. 3. A microprocessor based solid state controller system as claimed in claim 1, wherein the said housing is made of sheet metal comprising : a top portion, a central portion, and a bottom portion, - wherein the top portion is configured to hold the changeover selector unit, - wherein the central portion is configured to hold processor, - wherein the bottom portion is configured to hold the motor receptacle, - wherein the top portion is further specifically configured to receive power supply from ACB of conventional drive control system to feed the changeover selector unit, - wherein the top portion further is specifically configured to feed supply power back to conventional drive control system via changeover selector unit, - wherein the bottom portion is further spetifically configured to receive supply from conventional drive control system to feed directly to the motor terminals, and - wherein necessary electrical coupling and mechanical connections are provided between top, central and bottom portion of the housing. 4. A microprocessor based solid state control system as claimed in claim 1, as substantially described in the complete specification.

Documents:

0384-mas-2002 claims-duplicate.pdf

0384-mas-2002 claims.pdf

0384-mas-2002 correspondence-others.pdf

0384-mas-2002 correspondence-po.pdf

0384-mas-2002 description (complete)-duplicate.pdf

0384-mas-2002 description (complete).pdf

0384-mas-2002 description (provisional).pdf

0384-mas-2002 drawings-duplicate.pdf

0384-mas-2002 drawings.pdf

0384-mas-2002 form-1.pdf

0384-mas-2002 form-19.pdf

0384-mas-2002 form-26.pdf

0384-mas-2002 form-5.pdf