16 Jan Dig Deeper With SAE
In 2018, SAE was contracted to design and install the electrical grounding system for the main power transformer and communications tower at the new Barrie-Simcoe Emergency Services Campus located in Barrie, ON. Proper grounding systems are critical when dealing with possible high current surges to mitigate any risk to nearby personnel or electrical equipment. SAE designs all grounding systems in accordance with the Electrical Safety Authority (ESA) requirements for Ground Potential Rise (GPR) and the IEEE-80 requirement for step and touch voltage safety in the event of a line to ground fault.
The first step in designing a grounding system is to conduct a soil resistivity test. SAE uses a high-quality resistivity meter and the Schlumberger array method to collect resistivity data on the soil in the area to a depth of 100m. The soil resistivity data in ohm-meters or ohm-centimeters is then entered into CDEGS software to calculate a layered soil model. SAE engineers utilize this model, and the CDEGS software, to design a grounding system that provides a sufficiently low R-value, or resistance to ground. This ensures that any hazard from issues such as line to ground faults on the transformer or lightning strikes on the tower are properly mitigated.
After the proposed design was approved, SAE worked with other contractors on site to install an enhanced horizontal grounding ring and two enhanced vertical ground wells. Conducrete®, SAE’s conductive backfill, was utilized during the installation as an integral part of the grounding system. Surrounding the bare copper conductors in the ground with Conducrete® prevents corrosion, damage and theft, ensuring that the system performs as intended for the lifespan of the transformer and tower.
Once the installation was completed, the system was tested to check that the measured R-value of the installed system meets what was calculated in CDEGS. These measurements guaranteed that the grounding system will function as designed.
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