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Electrical Systems
• Electrical Engineering in Railways
– Rolling Stock
– Communications & Control
– Signalling
– LV Installations in Stations and Buildings
– Electrical Systems
Electrical Systems
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Electrical Systems
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High Voltage Aerial Lines and Underground Cables
Substations
1500V dc Traction System
– Overhead Wiring
– Traction Return
• Power Supply for signalling operation, communication
equipment, station and buildings, etc
• LV installations in Railway Tunnels and Yards
Electrical Systems
• Statutory Environment
– Rail Safety Act 2002
– Electricity Supply Act 1995
– Electricity Supply (Safety & Network
Management) Regulation 2002
– RailCorp is one of the Electricity Distributors
in NSW
High Voltage A.C.
Distribution System
• Standard Voltages
– 11kV
– 33kV
– 66kV
– 132kV
• Modes of transfer
– Overhead Transmission Lines
– Underground Cable
HV Aerial Lines
• Conductors
– Copper
– Aluminium (AAC or Aluminium Alloy)
• Conductor Supports
– Wood Poles
– Steel Poles
HV Cables
• Conductors
– Copper
• Construction
– Paper insulated lead sheathed
– XLPE
• Configuration
– Underground
– Galvanised Steel Troughing / Ground Line
Troughing
1500V D.C. System
• Electric Trains in NSW Run on 1500V D.C.
– Power is supplied from traction substations to
trains by means of the overhead wiring
(OHW) system
– Trains collect current through pantographs
sliding under the contact wire
– Current returns to the substations via traction
rails
Traction Substations
• Switchgear
– AC Circuit Breaker
– DC Circuit Breaker
• Transformers & Rectifiers
– Convert the high voltage ac supply to 1500V
dc
• Control and Monitoring
– SCADA (Supervisory Control and Data
Acquisition)
Traction Substations
• Substation Spacing
– Typically 4km to 15km
– Depends on a number of factors including
• Train loads
• Track grades
• Losses
• OHW types
• Train headways
• Electrolysis
Overhead Wiring (OHW)
• Overhead Wiring Systems in RailCorp
– Simple Catenary
• One or two contact wires supported by a
catenary wire
– Compound Catenary
• A main catenary supports an auxiliary
catenary, which in turn supports the contact
wire
– Contact Only
Overhead Wiring
• Tensioning Modes
– Fixed Anchored
• Wires rigidly anchored at both ends of the
wire run
• Tension in the wire varies with temperature
• Wire sags down at high temperatures
– Regulated Tension
• Tension is the wire is held approximately
constant
Overhead Wiring (OHW)
Overhead Wiring (OHW)
Overhead Wiring
Power Supplies
• Supplied from High Voltage Distribution System
– Generally from the 11kV Network
• Transform voltage to 415V or 240V
• Signalling Supplies
– Generally two independent source of supplies are
provided
– “Normal” supply from RailCorp HV Distribution
System
– “Standby” supply from local electricity distributor
• Power supplies to stations, buildings, workshops and
other LV installations.
Electrical Systems
• Challenges
– Reliability
• On Time Running
• Single Contingency (Except for OHW)
• Double or Triple Contingency at Critical Locations
• Design to minimise restoration time after failures
– Safety
• Statutory Clearances
• Permit System
• Safety in Design