21 Feb Err On The Safe Side With Effective Grounding
In 2019, SAE was contracted by Cascades Casino in North Bay, Ontario, to design the grounding system for the main supply transformer. After conducting soil resistivity testing and developing a layered soil model, it was evident that this area would not require an extensive installation for adequate grounding protection. Due to the minimal requirements, SAE determined that the next step would be to model a traditional grounding system and conduct testing to determine if the system would successfully meet the standards laid out by the Institute of Electrical and Electronics Engineers (IEEE) and Electrical Safety Authority (ESA).
A traditional transformer grounding configuration typically consists of a bare copper conductor grounding ring surrounding the transformer pad and 4, 10-ft. ground rods bonded to each corner of the ring. By modeling this typical configuration, SAE’s technical team determined that the ground potential rise (GPR) kept acceptable levels during a fault event. Still, a highly resistive surface layer of asphalt or concrete would be required around the transformer to protect it from hazards due to high touch and step voltages.
An alternative grounding system that utilizes Conducrete®: conductive powder backfill, was also engineered and designed to compare the performance of the Conducrete® enhanced grounding system to the results of the traditional configuration’s results. A similar grounding ring provides touch voltage protection, and an enhanced vertical ground well provides a low-resistance, low-impedance path to ground for a high magnitude current surge. This design reduced the requirements for a surface treatment while still protecting from touch and step voltage hazards.
An additional benefit to utilizing Conducrete® is that the conductive backfill extends the life of the system by protecting direct buried metal from corrosion – thus, less maintenance is required, and the system will not require replacement, as it lasts 20x that of a traditional grounding system.
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