Final answer:
The surface of a substation is covered with materials like crushed rock or concrete to help dissipate electric charges during faults for safety and to prevent shock. These materials provide insulation and dissipate heat. Ground fault interrupters and isolation transformers further enhance safety by preventing unwanted current flow and shock.
Step-by-step explanation:
The surface of a substation is usually covered with crushed rock or concrete to help dissipate electric charges that may occur during a fault. Substations, like other electrical systems, are designed with safety and functionality in focus.
When a fault occurs, such as a short circuit or other abnormal electrical conditions, there needs to be a way to manage the excess charge safely. Covering the surface with materials like crushed rock or concrete provides a high resistance layer, which can dissipate heat and maintain the insulation of the ground to prevent the flow of fault currents.
Materials like crushed rocks have sharp edges that can scatter the electrical charges, and they also limit the step and touch potentials, reducing the risk of electrical shock to persons near the substation during fault conditions.
Furthermore, in case of a fault where conductors might drop to the ground, the high resistivity layer helps prevent the flow of electrical current into the ground where it could create a potential difference and pose a shock hazard.
Ground fault interrupters (GFIs) and isolation transformers are other important safety components that help protect against electrical hazards. GFIs detect the loss of current to unintended paths, and isolation transformers insulate a device from the source, to prevent shock. These components, along with the right surface materials, work together to ensure the safety and reliability of substations.