Mine Power Distribution Equipment

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Mine Power Distribution Equipment
Voicu Grajdan
INDIH
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Contents

• Mine power distribution equipment
• Substations
• Switchhouses
• Mine load centres

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Mine Power Distribution Equipment
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Substations

• Power is supplied at high transmission voltages

• Substations step down this voltage to the mine
  primary distribution voltage

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Substation Transformer

• Most commonly liquid (oil) immersion type
• Integral three-phase preferred
• Advantages over three single-phase type
• Less expensive
• More efficient and reliable
• Takes up less space
• Less exposed interconnections

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Typical Main Substations

• 66kV/6.6kV substation
• 2 transformers
• Each having a capacity of 5 MVA

• Western Minings nickel mine in Windarra WA
  (formally)
• Transmitted to mine at 33 kV
• Transformed to primary voltage of 3.3 kV

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Portable Substations
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Switchhouses

• Provides a means of branching the power supply to
  mining operations
• Protects power system
• Portable equipment on skids or wheels

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Switchhouse Parts

• Visual disconnects manually cuts off power
  supply to downstream power equipment
• Sectionalising units
• Branches out the power supply
• Provides a protective relay for system

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Switchhouse Components

• High-voltage vacuum circuit breaker (can also be
  oil breakers)
• Solid-state or induction-disk relays
• Adjusted for both time delay and pickup current
• Current transformers used in conjunction for s/c
  and overcurrent protection

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Mine Load Centres

• An important power equipment in both u/g and
  surface mines
• Converts distribution voltage to the utilisation
  voltages required by mine equipment
• Also protects the system and mine equipment

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Load Centre

• Mounted on tyres, skids or tracks
• No standard configuration

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Load Centre Protection Devices (Pre-Transformer)

• Mechanically operated visual disconnect switch
  rapidly removes primary of transformer
• High voltage fuses protects primary of
  transformer
• Surge arrestors protect transformer from
  transient overvoltages

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Mine Load Centre Transformer

• Distribution ? Utilisation voltage
• Integral three phase
• Ventilated dry type
• Connections are delta primary and wye secondary
• Delta Isolates distribution from utilisation
  circuit
• Wye Provides resistance grounding

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Load Centre Protection Devices (Post-Transformer)

• Moulded-case circuit breakers because of low
  voltages
• These provide overload and s/c protection
• Zero-sequence relaying for ground-fault
  protection
• Continuity or impedance monitor types for
  ground-check monitoring

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Conclusion Australian Mines

• North Flinders Mines Ltd at The Granites, NT
• Power from main substation supplied u/g by 3.3kV
  cables
• Transformed at 3 portable substations
• Reticulated at 440V
• Renison Ltd, Renison Bell, Tas
• 2 x 11kV and 2 x 3.3kV feeders from main
  substation
• 30 u/g substations
• Most equipment require 415V power