Third Line Transmission Station
Tertiary System and Capacitor Bank Configuration Study

Selected Projects

Substation Upgrade Projects

● Anjigami Transmission Station
● Clergue TS Protection System Upgrade Project
● CNP - Gilmore Station P & C Upgrade Project
● CNP - Station 17 P & C Upgrade Project
● CNP - Station 18 Expansion Project
● D. A. Watson Transmission Station
● Mackay Transmission Station
● Niagara-on-the-Lake Hydro 115kV  MTS #2
● Patrick Street Transmission Station
● Patrick Street Ground Grid Upgrade Project
● Third Line TS - Tertiary System & Capacitor Bank Configuration Study
● Third Line TS - T1 Replacement Project


Location: Sault Ste. Marie, Ontario
Owner: Hydro One, Sault Ste. Marie LP
Engineer: OneLine Engineering

OneLine Engineering carried out a study to determine the cause of a failure of reactive compensation capacitors and the failure of the associated series reactor connected to the tertiary winding. The scope of work included:

• Collection of available data at site
• Setting up a simplified model of the power system to estimate the magnitude of voltage variations due to capacitor switching
• Use of the model to identify possible resonance frequencies
• Development of a Bewley lattice diagram to investigate the possibility of over-voltages due to wave reflections
• Review of data extracted from the existing multifunction relay to determine the possible presence of harmonics
• Determination of the adequacy of surge arresters protecting the transformer delta tertiary circuits and capacitors
• Ascertain the effectiveness of the existing grounding system
• Detailed design for the installation of new reactors
• Detailed equipment and installation estimate

OneLine Engineering is part of Cormorant Utility Services

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