CLIAMS:1. An improved system for control of stacking conveyors using wireless signal transmission comprising: at least four Radio Modem means installed in the respective drive houses (Remote Stations) of three conveyors & in plant substation (Master Station); at least four sets of RTU(s) means installed in the respective drive houses (Remote Stations) of three conveyors & in substation (Master Station); at least four Antennas means installed in the respective drive houses (Remote Stations) of three conveyors & in Plant substation (Master Station); and at least one display screen means installed in the control room for monitoring the stacking operation using wireless network & PLC.

2. The system as claimed in claim 1, wherein the said wireless signal transmission works on point to multipoint configuration where one master station communicates with remote stations of respective conveyors.

3. The system as claimed in claim 1 or 2, wherein a wireless signal transmission is established in Non-Line of Sight condition over a long distance for critical application in yard conveyors.

4. The system as claimed in anyone of the preceding claims, wherein inputs and outputs of the field devices are interfaced to RTU through auxiliary contacts of relays with proper isolation.

5. The system as claimed in anyone of the preceding claims, wherein a change over scheme is configured to switch over to old cable route in case of Radio failures using a selector switch.

6. The system as claimed in anyone of the preceding claims, wherein a display screen is provided for online monitoring & control of Process & Safety interlocks for yard conveyors.

7. The system as claimed in anyone of the preceding claims, wherein the said Radio Modem comprises of: (Pl include the hardware components) Frequency range: 410-470 MHz Communication mode: Half-duplex Carrier Power: 100 mW – 6 W Programmable. Interface: RS-232 or RS-485 Supply voltage: 12-24 Vdc Temperature range: -20°C...+70°C

8. The system as claimed in anyone of the preceding claims, wherein the said RTU comprises of : (Pl include the hardware components)Supply Voltage: +18v to +36v DC Digital Inputs: 8 nos. optically isolated Digital Outputs: 8 nos. potential free contacts, 250V-5A Analog Inputs: 2 nos. 0-20mA 12 bit resolution Analog Outputs: 2 nos. 0-20mA 12 bit resolution with internal Loop power. Communication Ports: 2 Serial PORT RS232 & RS232/RS485 Protocols: Modbus, ASCII Operating Temperature: -20 degree Celsius to +75 degree Celsius
,TagSPECI:FIELD OF INVENTION

The present invention relates to a system for controlling of the conveyors used in the field of stacking different materials. More particularly, the system describes an automatic and remotely controlling of stacking conveyors using wireless signal transmission technology.

BACKGROUND ART

When an industrial conveyors and another field apparatus cooperatively perform an operation, there is a case where an operation area of the conveyor overlaps an operation area of the cooperative apparatus, i.e., the conveyor and the cooperative apparatus share the same operation area. In such a case, it is necessary to prevent the industrial conveyor and the cooperative apparatus work in proper coordination & as per correct operational logic. According to a conventional manual method to ensure such coordinated operation, were very difficult. Stacking conveyors were earlier controlled using long distance control cables. Many times the signal from the motor house to the control room was lost due to breakage of control cables as a result harsh ambient conditions. This adversely affects the tippling & screening operation and production of the base mix. It was also not possible to introduce improved process & safety interlocks due to vast expanse of RMHP and limitation of number of cores in the cable.

On facing the aforesaid technical difficulties and further for remotely controlling the conveyors, a technological innovation has been achieved by RDCIS in association with Durgapur Steel Plant (DSP), Durgapur in the form of wireless transmission system in Stacking conveyor network of Raw Material Handling Plant (RMHP) of DSP.

In RMHP (DSP), conveyor A9 & A10A are used to stack screened lump ore on the beds of old area. Conveyor A10 is used to stack base mix on old area bed using wing trippers. The material which is stacked by these equipments on six beds is reclaimed using 4 reclaimer machines.. These conveyors feed the material to Sinter Plant & Blast Furnace through a network of other conveyors. The reliability of this stacking reclaiming sequence is dependent on the availability of stacking conveyors namely A9, A10 & A10A.

The present system has been designed, installed and commissioned for signal transmission based on wireless signals. The system comprises of radio modem & Radio Telemetry Unit (RTU) based transmitters & receivers which were integrated with the existing Programmable Logic Controller (PLC). Industrial radio modems encode, transmit and decode the data. The wireless system uses radio waves for data transmission & this medium of transmission gives user a lot of advantage over the wired data transfer.

SUMMARY OF THE INVENTION

According to principle aspect of the present invention there is provided an improved system for control of stacking conveyors using wireless signal transmission technology and the said system comprising: at least four Radio Modem means installed in the respective drive houses (Remote Stations) of three conveyors & in plant substation (Master Station); at least four sets of RTU(s) means installed in the respective drive houses (Remote Stations) of three conveyors & in substation (Master Station); at least four Antennas means installed in the respective drive houses (Remote Stations) of three conveyors & in Plant substation (Master Station); at least one display screen means installed in the control room for monitoring the stacking operation using wireless network & PLC.

A further aspect of the present invention is directed to said wireless signal transmission system for control Stacking Conveyors wherein said Radio Modem comprising
Frequency range: 410-470 MHz
Communication mode: Half-duplex
Carrier Power: 100 mW – 6 W Programmable.
Interface: RS-232 or RS-485
Supply voltage: 12-24 Vdc
Temperature range: -20°C...+70°C

Yet another aspect of the present invention is directed to said wireless signal transmission system for control Stacking Conveyors wherein said RTU comprising
Supply Voltage: +18v to +36v DC
Digital Inputs: 8 nos optically isolated
Digital Outputs: 8 nos potential free contacts, 250V-5A
Analog Inputs: 2 nos 0-20mA 12 bit resolution
Analog Outputs: 2 nos 0-20mA 12 bit resolution with internal Loop power.
Communication Ports: 2 Serial PORT RS232 & RS232/RS485
Protocols: Modbus, ASCII
Operating Temperature: -20 degree Celsius to +75 degree Celsius

Yet another aspect of the present invention is directed to the said wireless signal transmission system for control Stacking Conveyors comprising computer based human machine interface screen is installed in the dispatcher. The programmable logic controller gets the control signals using wireless network. The screen displays the real time data to the operator for stacking operation & status of process & safety interlocks.

OBJECT OF INVENTION

A principle object of the present invention is to provide an improved system for control of stacking conveyors using wireless signal transmission technology.

Another object of the present invention is to establish wireless signal transmission in Non-Line of Sight condition over a long distance for critical application in yard conveyors.
Yet another object of the present invention is to provide an improved system that caters to improved process & safety interlocks using wireless network.

These and other advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

Other features as well as the advantages of the invention will be clear from the following description.
Figure 1 illustrates the network architecture of wireless system in accordance with the present invention;
Figure 2 illustrates the Scheme of Digital Input/output Connections in accordance with the present invention;
Figure 3 illustrates the snapshot taken from Google Earth in accordance with the present invention;
Figure 4 illustrates the actual photographs of Wireless equipment panels & antenna in accordance with the present invention;.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and illustrate the best mode presently contemplated for carrying out the invention.

The present invention relates an improved system for control of stacking conveyors using wireless signal transmission technology. The improvement is over the control & automation part of stacking conveyors.

The system comprises of radio modem & RTU based transmitters & receivers which were integrated with the existing PLC. The wireless system uses FUNK radio operating on a frequency band 410-470 MHz. DIs & DOs are connected to radio RTU 1400D of LOTUS wireless. The Basic Module of RTU has 8 optically isolated inputs, 8 potential free outputs, 2nos. of 0-20mA Analog input and 2 nos. 0-20mA Analog outputs. RTU modules are easily mountable and scalable. Its plug-in screw terminal blocks make it easy in electrical connection to the devices. RTU at each of the three remote stations (drive houses) caters to 10 DI & 10 DO whereas RTU at master station (Lime Plant Substation) caters to 30 DI & 30 DO. Field signals were at first connected to interfacing relays, and then they were connected to the RTU. Radio modem receives signals from RTU & transmits them to master station wirelessly. At master station, signals are received by the master radio modem. Modem gives the signals to the RTU. Output signals of the RTU are processed in PLC through interfacing relays. Scheme is similar for signal transmission from master station to remote stations. Signal exchange from three remote stations (drive houses) to the master station was tested & taken online one by one. Process & safety interlock signals like under speed sensors & chute jamming etc. which were transmitted through wireless network, were introduced in the existing PLC. The network architecture of wireless system as disclosed herein is illustrated in Figure 1. The architecture was designed based on point to multipoint configuration where one master station communicates with three remote stations of respective conveyors. RF power in radio modem was optimized to have good signal strength. Polling delay & RTU drop out time were also adjusted for a reliable communication. The methodology adopted for connection of digital input/output connection to the RTU is shown in Figure 2. The control & interlocking signals which are required for running of these stacking conveyor motors like start, stop, under speed, chute jamming etc. These signals are communicated between drive houses (remote stations) and Lime Plant Substation (master station) through wireless signal transmission.

The signals are connected to the RTU using interfacing relays. The Scheme is common for all the three drive houses (remote stations). The distance between three remote stations & master station is approximately 1 Km and there is no clear line of sight between them. A snapshot taken from Google Earth is shown in Figure 3, illustrates the communication between Master station & Remote station is shown using graphics. This gives an idea of the distance between master station & remote station. The referred figure also gives an idea of Non- Line of sight condition. . Therefore, to have a secure & reliable wireless network, UHF frequency band was used. The Operating frequency license was obtained from Wireless Planning Commission (WPC). The Wireless equipment panels & antenna installed at master station (lime Plant Substation) is shown in Figure 4.

INDUSTRIAL APPLICABILITY
1. Similar schemes can be implemented in various areas where long distance cabling is to be eliminated by wireless communication like RMHP, Mines, Coke ovens, Sinter Plant etc.
2. The system developed has huge possibilities of technology transfer in areas where there is no line of sight between transmitting & receiving station.

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 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. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.