On 27 September 2016 there was the fourth webinar of the series "In simple words about installation of grounding and lightning protection", at which there was a discussion about electrical substation. The general director of an electric-installation company "N G N Group" Ltd. Sergey Alexeevich Tolstopyatov told about how to make the right calculation and installation of grounding and lightning protection, observing the existing requirements . In addition to the main program of the seminar, upon the request of the participants, the topic of grounding and lightning protection of a diesel power station was observed.
During the webinar there were a lot of questions from the participants, so we have prepared navigation on the responses that our expert gave:
- Are active lightning rods applied? 28:34
- Can they be considered as part of the internal grounding contour of the metal doors frames and gates? 29:57
- How effective is the use of lightning protection mesh? 31:03
- What proves the height of the inner contour of 0.6 m? Why not use the height above the cupboards, for example, 2.4 meters? 32:43
- Can I go outside the perimeter of the grounding device? 40:08
- Screws, bolted to the metal structure, are considered to be good grounding? 40:54
- Is it possible to adopt EIC grounding norms for temperate climate in the calculations in permafrost soils if the soil is bulk? 42:56
- 12 vertical ground electrodes 7 meters high and 90 mm in diameter are used in bulk soil. Do I need to fill them not only with bulk soil, but with graphite mixture? 47:16
Answers to frequently asked questions were given to the chat by our technicians. Here are some of them:
Question: is the height of running the internal grounding contour (earthing grid) somehow limited? We run the contour at the height of 2 meters at our substations. Is it allowed?
Answer: the recommended height of running the contour - 0.6 m. There is no strict normative document for this case, only recommendations with the wording "should".
Question: how to properly ground sandwich panel at the substation? Should every panel be grounded separately?
Answer: if the building is specially designed to contain the substation control building, the construction of buildings made of sandwich panels has electrical continuity. It is not necessary to ground each panel separately. Contact resistance between the elements used for lightning protection, should be less than 0.05 ohm. It is checked by the microohmmeter or insulation resistance tester.
Question: Is it necessary to intall vertical lightning rods in buildings where the roof thickness is less?
Answer: it is desirable to use wire or rod system. Each case is studied individually.
We thank all the participants for their active communication and invite to the next lecture on October 11, 2016 - "Grounding and lightning protection for a tank farm". Videos of previous seminars see here.