Early collision warning system uses very low frequency.
The VAK Electronics CWS 800 collision warning system, supplied by Booyco Electronics, has been designed to reduce the number of accidents occurring between pedestrian workers and heavy capital equipment in the mining environment.
Extensively tested in mining applications such as platinum, gold, base metals and coal, the system is suitable for use both underground and above surface in traditional mining as well as earthmoving applications.
Operating principles
The CWS 800 combines both very low frequency (VLF) and radio frequency (RF) technologies to provide mines with a very effective two-way communication safety enhancement system.
Two-way communication underground can often be compromised by the presence of certain ore bodies and the physical thickness of the rock itself. The use of VLF technology, however, eliminates this uncertainty, providing a stable and unbroken line of communication between tagged personnel and vehicles.
The CW 800 system comprises a VLF and RF two-way communication tag built into a cap lamp, a machine control unit fitted with an alarm, one or two-loop antennae on each vehicle, a power supply and an additional tag reader in each static danger zone.
The system transmits a VLF signal via the antenna to create a warning zone in front of and behind the vehicle. The fully encapsulated antenna is mounted in a non-static plastic enclosure and provides a stable field around the equipment for greater accuracy.
The CWS 800 system has a smaller detection range when compared to high frequency VHF and UHF, but this does not impact on the operation as too large a detection range would result in a tag picking up a signal from too far away.
Warnings and extended functions
The system has an outer and inner zone area which is adjusted to suit the equipment on which it is mounted. When the pedestrian enters the outer zone, the VLF tag fitted in his cap immediately alerts him to the fact that there is a moving vehicle within close proximity to him. This warning can be conveyed via a flashing lamp, an audible buzzer or both. This warning signal remains constant until such time that the pedestrian leaves the outer zone completely.
The virtual dividing line between the outer and inner zone is usually set at 50% of the outer zone extent. When the pedestrian enters the inner zone the driver of the vehicle is alerted to his presence, via the machine’s control system by means of a flashing light and buzzer mounted in a position where the driver has optimum visibility.
The system is supplied in two versions, one for surface use and a second for underground use. The system provides both personnel and vehicle warning. It also offers expanding possibilities to optional clocking in and out of personnel and mine clearance as well as protection against entering certain hazardous areas underground.
The CW 800 system forms an integral part of Booyco Electronics’ comprehensive safety enhancement system and, combined with its asset management software, is able to provide accurate real-time feedback on the exact location of both workers and vehicles at any position within the mine.
It is important to remember though that the CW 800 is not a safety system. It is a driver aid and enhancement to assist both the equipment operators and the pedestrian personnel as a warning system. The responsibility for safety still resides with the individual.
For more information contact Anton Lourens, Booyco Electronics, +27 (0)11 974 8640, www.booyco.co.za
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