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

• 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