CWS 800

The CWS 8OO collision warning system uses very low frequency technology (VLF) to provide miners and drivers with a personal communication tag to create a warning zone of a stable and predictable shape and size on moving machinery.

System Operation

The design philosophy utilises the following logic:

When a pedestrian approaches a traffic light at an intersection and the red light is showing pedestrians not to cross, it is up to the pedestrian to heed the warning and it is irresponsible of pedestrians to rely on drivers to give way to jaywalkers. If the pedestrian decides to jaywalk, he has to consciously override the warning light in front of him and he has to be held accountable for this decision.  Similarly the CWS800 in its basic form warns the miners of an approaching vehicle.  The system does however have additional 2-way communication which can be used amongst other things to warn the operator of the mobile equipment that there is a miner within dangerous proximity of his vehicle (who might not have been in sight of the operator) as a second warning zone. The system can also be expanded to provide other functions such as confirmation of shaft clearance and time and attendance (T&A).

The system employs very low frequency (VLF) and radio frequency (RF) technology.  Miners are equipped with 2-way RFID tags.  Vehicles or other static danger zones are equipped with VLF antennae which creates two stable fields of a predetermined size and shape in front of and behind the vehicle.  When a miner enters the zone in which the field is established, his tag is activated and the warning signal is triggered indicating to the miner that he is entering a danger zone, be it a static danger zone or an approaching vehicle.  Antennae on vehicles are only energised when the vehicles are in motion.  With these 2-way tags the operator of the vehicle can also be warned that a miner has entered his danger zone.

The antennae create warning zones of up to 15 m in a stable, predictable shape and size.  The size of the warning zone that can be achieved is dependent on the power available e.g. from intrinsically safe (IS) power supplies or DC/DC converters.

CWS 800 System Functions

- Mobile equipment detection and warning given to the miners at risk
- Warning given to the operator if an intruder has entered his vehicle’s danger zone
- No false warnings from stationary machinery
- Personnel identification, clock in/out and mine clearance
- Warning against going into dangerous areas for example conveyor reloading point or unsupported roof areas

Hardware Required:

- Radio Frequency (RF) communication tag for each person in a mine
- Radio Frequency (RF) machine control unit for all mobile equipment in a mine
- An alarm unit to indicate warning to the driver, and/or to control external devices or interlock with equipment
- One or two loop antenna (two for vehicles longer than 8 m)
- A test unit for both pedestrian and vehicles tags at each point of entry, or typically in the lamp room
- A VLF reader in each location prohibited for entry zone (optional)

Hardware Description

Machine Unit
The unit transmits a VLF signal of less than 15,0 kHz via loop antennae which creates a warning zone in both directions of travel for underground use.
When required to additionally warn a driver, the control unit then receives a UHF signal from the miner’s tags before activating the relevant alarms.
The unit will disable the driver’s tag when a driver is in the cabin.
Power requirement is regulated 12VDC.

Alarm Unit
The unit responds to the machine control unit activated through the receipt of a UHF signal from a tag.
The unit facilitates relay contacts to activate additional alarms or interlock with equipment.
The unit has both visual and audible alarms in the event of an activation.

Ferrite Antenna
The antenna is mounted in a resin filled, non-static plastic enclosure, and contains a resonance circuit forming a multi-turns loop.
On machinery longer than 8m, two antennae should be installed with one unit on opposite ends of the machinery.
On shorter machinery, one antenna in the center is sufficient.

Personnel Tags
The IS approved tag is fitted into a cap lamp cover, and flashes the miner’s cap lamp to warn a miner on the approaching machinery.
The tag reacts only when receiving a signal from the control unit, and as such deemed to be in a hazardous position. Therefore, tags do not pollute the electro-magnetic (EM) environment.
The tag consumes less than 100 µA.

Test Units
The test unit is installed at a safe point of entry or lamp room area in such a position that personnel have to pass by the test unit to confirm that the tag is functioning correctly before the start of shift.
The unit transmits short range (2,0 – 3,0m) VLF to initiate the tag and receives the UHF signal in response (and registers the miner’s ID if a 2-way system is used).

Optional
An IS approved audible alarm unit can be provided for underground use as part of personnel tag.

Upgrading The System

The system can be upgraded for optional functions if required

Installation, Service & Maintenance

- The system can be upgraded for optional functions if required
- Booyco Electronics have trained personnel that are able to support and maintain all of the system components
- The system promotes “Plug and Play” capability to ensure easy repairs and reduce down-time
- It is recommended that the system is maintained under a standard maintenance agreement
- Training must be provided to end users/relevant mine personnel to ensure user buy-in and product acceptance