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Overview of a Minecom Leaky Feeder System
Communications Rack
Located on the mine surface (in IS mines), it contains:
- Head End Unit (up to 32 channels) interfacing Leaky Feeder cable & Base radios
- Leaky Feeder Power Supply and Battery Backup
- Base radio equipment
- Surface coverage antenna system
- Surge arrester protecting Head End Rack
- Audio Bridge interfacing and controlling the audio channels
- Repeaters and Isolators
- Non radiating coaxial cable RG400
- 27RU, 39RU & 47RU robust Rack enclosure.
Leaky Feeder Cable 20-00007/8/20, 20-00040/41 (MSHA)
Distributes power and RF signals throughout the mine. Available in 350 m (1148 ft) and 500 m (1640 ft) drums. Robust and flexible cable has foam dielectric protecting system from harsh environment.
Amplifier 01-20001
Amplifiers are installed at regular lengths along the cable to maintain signals levels. Featuring Automatic Gain Control, adjustable attenuation and local diagnostics LED display.
Power Coupler (PC) 01-20004
Injects power through leaky feeder cable to power amplifiers. Power Couplers are compatible with 12 V 24 V and 48 V DC systems.
Single Branch Unit (BU1) 01-20003
Used to split an additional path tunnel or level from the main Leaky Feeder cable.
Dual Branch Unit (BU2) 01-20015
Used to split two additional paths tunnels or levels from the main Leaky Feeder cable.
Joiner Box (JB) 01-20006
Joins two ends of Leaky Feeder cable together to allow the system to work correctly - preventing further losses and damage to the cable.
Termination Box (TB) 01-20010
Seals the end of the cable and protects against harsh mine environments. MSHA requires the last amplifier in a cable run to have a termination unit.
Antenna Coupler 02-00063
Provides the same function as the termination box with extended coverage via an omnidirectional antenna.
Power Station (Non IS) 02-00067/93
Provides power to a minimum of 3 amplifiers from a single 120 V (240/220 V available) single phase source. Available in 24 VDC or 48 VDC. For Non-IS environments only.
Emergency Call Station 05-00018
Features alarm and siren, remote emergency diagnostics remote or manual alarm activation/deactivation from handheld or vehicle radio. For Non IS environments only.
Isolation Barrier (IB) 01-20014
Provides DC isolation and transient voltage protection. Placed just outside surface & safe underground and just outside safe underground & hazardous areas.
Battery Backup
The Pyott Boone 1953 & 1955 Battery Backup provides 24 and 96 hours of battery backup for the Minecom Amplifiers. In an IS environment MSHA require battery backup for each amplifier in the communications system.
Power Station (IS)
The Pyott Boone 1925 Power Supply has 2 independent 24V1A outputs which powers a total of 4 Minecom amplifiers from a single 120V single phase source.
Minecom’s next generation amplifiers incorporate our new ZeroCal™ technology and Automatic Gain Control (AGC) circuits to ensure the entire leaky feeder system is kept in balance and no calibration is required. Microprocessor controlled attenuation circuits automatically maintain a constant signal level, regardless of cable loss, and prevent unwanted signal gain entering the communications system.
