Importance of safety protection
Another extremely important substation engineering aspect is associated with safety protection. It is fair to say that safety is always a No. 1 priority in substation design, operation and maintenance.
Unlike the case where a higher reliability required a larger investment, we can’t put a price tag on safety since there is no such thing like working conditions being more or less safe. It should always be 100% safe to work at or visit the substation.
There are numerous laws, rules, codes, etc. governing safety requirements; of the most important being “IEEE Standard C2-2012. 2012 National Electrical Safety Code®” (NESC®)
Safety standards contain requirements for:
- Enclosure of electrical equipment
- Rooms and spaces
- Floors, floor openings, passageways, stairs
- Installation of equipment:
- Protective grounding
- Guarding live parts
- Working space above electrical equipment
- Specific rules for installation of all typical substation equipment
All these measures are based on common sense and the goal to provide a safe environment for substation personnel.
6 rules to provide substation safety
Rule no. 1 (clearance)
Enough clearance from energized parts should be provided to avoid accidental contact with them. If that can’t be met, live parts should be guarded or enclosed.
Rule no. 2 (minimum height)
A minimum height from the ground to any ungrounded part of an electrical installation should be 8’-6”, so a person staying on the ground can’t touch a substation element or its part which may become energized accidentally. For example, the bottom of a post insulator supporting an energized bus does not normally have any potential.
Rule no. 3 (illumination…)
There should be sufficient illumination for personnel to clearly see their surroundings and perform any work safely. Required illumination levels are specified in NESC® .
Rule no. 4 (passageways…)
All passageways and stairs should be wide enough for personnel to navigate them safely, adequate railing should be provided, and floor openings should have guard rails.
Rule no. 5 (evacuation routes)
Exits should be clearly marked and evacuation routes should be free from obstructions. Depending on the function of the building (for example, control house), it may require several exits to avoid personnel being trapped during equipment fault, fire, etc.
Rule no. 6 (grounding, as always)
All substation metallic structures, fences, and equipment tanks should be connected to a station ground grid which should be designed to ensure that step and touch potential values are lower than the ones stipulated in the applicable standards.
Reference: Fundamentals of Modern Electrical Substations; Part 3: Electrical Substation Engineering Aspects by Boris Shvartsberg, Ph.D., P.E., P.M.P.