Capital investment in a typical continuous miner (CM) is running to several millions of rands. System availability of these systems is often less than 50% due to the extremely harsh operating conditions.
Coupled with the legal and moral responsibility upon mine management to ensure that these machines are operating safely and without risk to operating personnel, CM users are continuously striving for more effective means of monitoring and managing the systems. However, the geographical separation between the machine operating underground and the management infrastructure on surface presents unique challenges to monitoring the operation of the machine in realtime.
On-board methane interlocking systems have been extensively used since the mid-1990s to shut down the CM's cutting drum in the event of dangerous levels of methane or in the event of a failure of the water spray systems. In addition, underground telemetry systems have been available in the coalmines for some years and have extensive application in environmental monitoring. However, providing a robust and reliable data link between the mines data communications infrastructure (or fixed environmental telemetry system) and the mobile CM has presented a significant technical challenge and has, until very recently, prevented the integration of the environmental monitoring system and the CM for realtime CM monitoring or interlocking of the off-board secondary ventilation fan.
The Spero solution
During 1997 and 1998, the Spero Group developed a harsh terrain telemetry system, specifically designed for underground mining applications. This system, the SL2000 telemetry system, was initially developed for nonfiery mines, gaining wide acceptance as a South African standard in gold and other deep mines during the following years.
During 2000, further developments were made to the system to allow its application in hazardous areas in fiery mines. Explosion protection certification was obtained from the SABS and the first coal mining installations were conducted during 2000.
From the outset, the Spero Group recognised the need in coalmines to monitor on-board CM systems in realtime and adopted the approach of extending the SL2000 system, with all of its benefits and features for monitoring and control, on-board the mobile CM and long wall mining systems.
Both the MMA200 on-board CM monitoring and control system and the MM700 secondary ventilation fan interlocking system were developed on the foundation of the considerable expertise in robust and reliable data communications in harsh underground mining conditions built up over several years during the development and deployment of the SL2000 system. Since both the MM700 secondary ventilation fan interlocking system and the MMA200 on-board CM monitoring and control system are effectively constructed using largely standard SL2000 system modules, the system may be configured as a standalone system for those mines which have already invested in (a nonSL2000) underground environmental monitoring system or require, for example, only fan interlocking.
Alternatively, the on-board systems infrastructure may be integrated with an existing SL2000 underground telemetry system (or extended in phases) into a full-fledged mine-wide environmental monitoring and control system, without having to sacrifice any of the original investment of MM700 or MMA200 equipment.
System description
The heart of the Spero Group on-board CM monitoring and control systems (and indeed the SL2000 telemetry system) is the LonWorks communications protocol which allows for robust and reliable data communications over a range of communications media including fibre optics, 10Base-T Ethernet channels, twisted copper pair and/or power lines, using a single communications protocol.
It is the last, ie reliable power line communications, which allowed Spero Group to develop its range of on-board data communications systems and resolve the technical challenges that had hampered the development of similar systems in the past. By superimposing two-way data communications onto the existing high voltage trailing cable supplying power to the machine, both off-board secondary ventilation fan interlocking (MM700 system) and remote machine status monitoring (MMA200 system,) can be reliably and cost effectively achieved.
Due to the modular design concept implemented in the system architecture, various turnkey options are offered to clients to suit their differing needs. However, due to the common technological foundation of the different system configurations all systems are compatible with each other and the client has the option of upgrading from one configuration to the next at minimum additional cost and without having to discard existing system equipment.
The system options are described below:
* MM700 (off-board secondary ventilation fan interlock to CM cutting drum)
The MM700 off-board secondary ventilation fan interlocking system is a self-contained bolt-on system contained in two flameproof boxes that may be mounted onto virtually any CM and gate-end box combination. The system is therefore not restricted to any particular make or model of CM. In addition, the system may be configured to interlock several off-board fans (each fan being individually selected by means of a switch on the controller) to a single CM, thus obviating the need to connect and disconnect fans during mining operations.
The MM700 fan interlock system monitors the secondary ventilation fan motor load current by means of a controller that is mounted inside a flameproof box and connected in-line with the fan power supply cable on the gate-end box. The fan status is communicated via the three-phase 1000 V a.c. power cable to a second controller (mounted in a flameproof box) on the CM. The fan interlock status is output via a potential-free, normally open relay contact, which is connected to the cutter drum control circuit to trip the drum under fault conditions. An override keyswitch is incorporated into the on-board controller to allow the operator to override the fan interlock when the machine has not yet penetrated 12 m from the last through road (as per the requirements of directive B7).
The system is fail-to-safe so that the interlock will operate in the event of equipment or power failure or in the event of a loss of data communications between the gate-end controller and the machine-mounted controller. Status indicators are also included to facilitate fault finding in the event of equipment failure.
Communications between the gate-end box and CM is by means of the same LonWorks protocol as used in the MMA200 and SL2000 underground telemetry system.
* MMA200
The MMA200 realtime remote CM monitoring system comprises three system components, namely a surface installation, communications infrastructure and machine-mounted equipment. The MMA200 surface installation includes a personal computer with network interface card and Windows NT operating system running the scada software that provides the operators interface
The system employs the Citect scada package to provide the operator interface and data processing and archiving. This allows for remote monitoring of the machine data at a number of view nodes located virtually anywhere on the surface Ethernet LAN infrastructure.
An additional system option, using a TCP/IP link via the Internet, allows data to be viewed remotely from any point globally that has a telephone connection. This will allow managers and supervisors to monitor machine performance from remote locations (while at home, for example) or allow scarce maintenance personnel to monitor system performance and make technical decisions prior to deploying maintenance resources underground.
The MMA200 communications infrastructure includes the data link between the surface control room and the section where the machine is located, together with signal routers, power supplies and other network hardware required for the telemetry system. The communications infrastructure comprises existing SL2000 telemetry system modules and is tailored to the specific mine conditions (mine layout, distances covered, existing infrastructure, etc). For those mines already employing the SL2000 system for environmental monitoring and control, virtually no additional hardware or software will be required since the communications infrastructure and surface installation will already exist.
The communications backbone is generally a twisted copper telephone wire pair, but may incorporate fibre-optic, Ethernet LAN communications or indeed any of the communications media types used by the SL2000 system, meaning that the system may be optimised to fit in with the mine's existing infrastructure to achieve considerable cost savings.
The MMA200 machine-mounted equipment comprises a 16 analog and 16 digital channel communications transceiver, supported by associated power supply and interface circuitry, mounted on-board the CM. The on-board equipment communicates via power-line coupling electronics over the three-phase 1000 V a.c. power cable to a signal router mounted at the section gate-end box, meaning that no extra communications cable is required between the CM and section gate-end equipment. From the signal router, the data is communicated, via the communications backbone described above, to the operators scada console on surface where the data may be viewed, processed and archived or further distributed to different users of the data.
The on-board equipment is a self-contained, bolt-on system, packaged in two flameproof boxes that may be mounted onto virtually any CM. The MMA200 system is therefore not restricted to any particular make or model of CM. It is fully compatible with both Joy and Voest Alphine manually operated as well as remote-controlled machines.
Customers using a combination of machines from different manufacturers therefore have a cost effective means of being able to monitor all of their machines using a single data monitoring and control system and communications infrastructure. Since the system is also based on standard SL2000 building blocks (routers, transceivers, control room installation and network management software), users obtain the benefits, including spares availability and continuing system development and improvements, of a large installed customer base.
The capability to monitor 16 analog (4-20 mA industry standard) inputs as well as 16 digital I/O channels, means that the user can monitor, in realtime, virtually any mix of the following parameters and the data may be recorded for later retrieval and analysis:
* Methane, water flow or pressure (from the Spero Group MM100 methane monitoring system).
* Motor load currents.
* Oil temperature and pressures.
* Contactor status (open/closed inferring motor running/stopped).
* Boom position.
* Cutting times.
* Shift start and end times.
* Communications link status.
Two-way communications between the machine and other nodes (transceivers, for example) on the communications network means that it is possible to perform limited remote control functions, including, for example, the ability to interlock the (off-board) secondary ventilation system with the cutting drum or to remotely trip the cutting drum in the event that a dangerous situation is detected or some critical machine parameter (motor load current or gearbox temperature) goes outside of a preset limit.
* MM1000
Spero on-board systems have been designed to integrate seamlessly, and work in conjunction with each other, including the Spero Group MM100 methane monitoring and interlocking system, already widely used throughout the South African coal mining industry. The features of the MM700, MMA200 and MM100 systems have been combined into a single turnkey package, designated the MM1000 system.
Features of the MM1000 combined on-board systems include:
* Meets all local statutory requirements - offers, for the first time, full compliance with DME directive B7
* Offers extremely cost-effective means of remote machine monitoring - superior functionality at a fraction of the cost of competing products.
* Reduced ownership costs - one system type can monitor and interlock all machine types.
* Proven technology - over 150 (MM100) systems installed; more than a dozen SL2000 sites countrywide.
* Locally developed and manufactured for South African conditions.
* Demonstrated performance and reliability (demonstrated communications link availability approaching 100% provided integrity of the physical medium (such as telephone cable) is maintained).
* Designed for ease of maintenance.
* Fail-to-safe design.
* In situ calibration using test equipment supplied with the system.
* On-going product improvements.
* Backed up by 24/7 call-out service and parts availability.
* Full on-site training support.
* May also be integrated onto longwall systems.
* Remote, off-site machine status monitoring (via Internet).
Spero Group
(012) 665 0317
| Tel: | +27 12 665 0317 |
| Email: | [email protected] |
| www: | www.spero.co.za |
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