A typical modern continuous miner (CM) involves a capital investment to the operator of several millions of rands. With the system availability of these systems often being less than 50% due to the extremely harsh operating conditions, 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. 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. Until very recently, the different methods tried, eg, radio frequency data communications, have not proven to provide a reliable or cost-effective solution.
Spero's solution
During 1997 and 1998 the Spero Group developed a harsh terrain telemetry system, specifically designed for underground mining applications. The SL 2000 telemetry system, was initially developed for, and sold to, non-fiery mines, gaining wide acceptance as a South African standard during the following years.
During 1999 and 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 to monitor on-board CM systems in realtime and adopted the approach of extending the SL 2000 system, with all of its benefits and features for monitoring and control, on-board the mobile CM and longwall mining systems.
The MMA200 on-board CM monitoring and control system was 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 SL 2000 system. While the MMA200 on-board CM monitoring and control system is effectively built up using largely standard SL 2000 system building blocks, the system may be configured as a standalone system for those mines which have already invested in (a non-SL2000) underground environmental monitoring system. Alternatively, the MMA200 infrastructure may be extended over time into a fully-fledged mine-wide environmental monitoring and control system, without having to sacrifice any of the original investment of MMA200 equipment.
System description
The heart of the MMA200 on-board CM monitoring and control system (and indeed the SL 2000 telemetry system) is the LonWorks communications protocol which allows for robust and reliable data communications over a range of communications media including fibre-optics, 10BaseT Ethernet channels, twisted copper pair and powerlines, using a single communications protocol. It is the last - that is reliable power-line communications that allowed Spero Group to develop the MMA200 and resolve the technical challenges that had hampered the development of similar systems in the past.
The MMA2000 system comprises a 16 analog and 16 digital channel communications transceiver, supported by associated power supply and interface circuitry, mounted on-board the CM. This communications transceiver communicates via the 3-phase 1000 V a.c power cable to a signal router mounted at the section gate-end box, meaning that no additional communications cable is required to link data communications to the CM. From the signal router, the data is communicated via a communications backbone (which 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 SL 2000 system) to an operators scada console on surface where the data may be viewed, processed and archived or further distributed to different users of the data.
The system is a self-contained bolt-on system which may be mounted onto virtually any CM - it is therefore not restricted to any particular make or model of CM. 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. The system is also based on standard SL2000 building blocks (ie routers, transceivers, control room installation and network management software) ensuring the benefits, including spares availability and continuing system development and improvements, of a large installed customer base.
Furthermore, because the system offers the capability to monitor 16 analog (4-20 mA industry standard) inputs as well as 16 digital I/O channels, the user can monitor virtually any mix of the following parameters (which) 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 (ie, open/closed inferring motor running/stopped).
* Cutting times.
* Communications link status.
Two-way communications between the machine and other nodes (eg, transceivers) 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 (eg, motor load current or gearbox temperature) goes outside of a preset limit.
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 allows data to be viewed using a standard Internet browser using a TCP/IP link via the Internet. This will allow managers to monitor machine performance from remote locations (eg, while at home) or allow scarce maintenance personnel to monitor system performance and make technical decisions prior to deploying maintenance resources underground.
System benefits
The MMA200 system has been designed to work in conjunction with the Spero Group MM100 methane monitoring and interlocking system, already widely used throughout the South African coal mining industry. Features of the combined MM100/MMA200 system include:
* Cost-effective means of remote machine monitoring.
* Over 150 systems installed.
* Locally developed and manufactured for South African conditions.
* Meets all local statutory requirements.
* Demonstrated performance and reliability (demonstrated communications link availability approaching 100% provided integrity of physical medium (eg, 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.
* Remote (surface) machine status monitoring.
* May also be integrated onto longwall systems.
| Tel: | +27 12 665 0317 |
| Email: | [email protected] |
| www: | www.spero.co.za |
| Articles: | More information and articles about Spero Sensors & Instrumentation |
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