Power System Analysis and Fault Protection Studies for 120 QUU Sites

Client: Queensland Urban Utilities

Technology: SKM PTW (Power Tools for Windows)

Witthoft Engineering undertook an audit of each site to ensure the integrity of the earthing system, that AS3000:2007 requirements regarding clearance around switchboards, access and egress ways were met, and to confirm as-built information required to perform the power system analysis including:

  • Energex Connection Details (Pole #, Meter, Connection Type, Transformer Details)
  • Circuit Breaker Make / Model / Settings
  • Cable Types / Sizes / Lengths / Installation Methods
  • Drive Make / Model / kW / FLC

We then performed the power system analysis to identify issues with the operation of the existing equipment with respect to:

  • Improperly coordinated protection schemes
  • Lack of discrimination in some circuits
  • Incorrectly set protective devices
  • Improperly designed protection systems
  • Excessive fault clearance times resulting in high incident energy levels and risk to operations personnel
  • Risk to operations personnel when operating the control panel (Reset/Start/Stop pushbuttons) (where applicable)
  • High prospective arcing currents exceeding rating of existing PPE
  • Power factor
  • Touch Potential

Finally, we provided the client with a report for each site containing:

  • All protection device settings and Time Current Curves
  • Comparison of the existing protective device settings against new settings.
  • Categorisation of major switchboards with relevant labels designed for installation on each switchboard.
  • Assessment of existing system to confirm adherence to AS3000:2007.
  • Assessment of the new system to confirm adherence to AS3000:2007.
  • A summary of findings.
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