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Hi, My question is about routing conductor around a 240kV transfromer Sorbweb oil containment. The issue is that the containment area (14.5 x 32.5 m) is pretty huge compared to the transformer pad (4 x 9 m). If we are to install conductors below containment they will have to be installed at...

Keep in mind one more issue that we previously experienced for a 240kV breaker terminal pad. A smaller pad will have a greater temp rise for higher ampacity. This is especially an issue with breakers which have the max operating temp of limited (ref. IEEE 62271-1, Table 5.1). You may use IEEE...

You might want to complete a Fall of Potential test if possible to see what the ground resistance of grounding system is like. If bonded proprely, the building rebar would be very beneficial in dissipating ground current. If possible, you may also consider installing a ground wells and remote...

Great point @scottf about stray capacitances. I will keep those requirements in mind.

Thanks a bunch for everyone's response. @cuky2000 Your reply does make sense. Is there a simulation program that can be used to estimate the potential at each point on the insulator? My guess is that the potential drop would not be linear through the surface of the CVT insulator.

Hi Everyone, Our utility clients usually specify a minimum phase to ground clearances for high voltage (>69kV) substations. While we always meet those requirements, what potential issues would you all see in the following arrangement: A live wire jumper is connected in such a way that it meets...

If the transformer is solidly grounded on the high side, you might want to consider that return path as the design criteria

Hi RS, As stated by everyone else, it is impossible to state whether calculated potentials will exceed threshold limits without using a detailed grounding simulation. However, I can share some of my experience studying similar situations: Transfer of potential to a nearby facility fence due...

Hi Everyone, I am designing a 240kV AIS substation for a utility client. Their standards and specifications specify a bus rating of 3000A. For flexible jumpers, I specified 2x2000 MCM ASC conductors to satisfy the ampacity rating. The client came back and told us not to use 2000 MCM conductors...

By 'we use' do you mean a in certain geographical area?

Actually, for the electrical and civil group doing the work, grounding was an after-thought. It was only after the client insisted that they agreed to get a grounding study done. Hence they have little idea or appreciation for grounding hazards due to a utility level fault current. And thanks...

@va3mnr Thanks for your suggestion. We did try completing a test for top soil layers. However early winter frozen soil + highly compact top layer effectively rendered those measurements useless with no budget for further testing. And we cant wait til summer conditions to redo the test as the...

@davidbeach Thanks for sharing your experience. @stevenal By qualified, I mean that the civil guys are persisting that this coarse gravel top layer is enough to be considered as an insulating gravel layer in our grounding study. But as a grounding engineer, it's my job to recommend if...

Hi, We are designing a grounding system for a pipeline terminal which is being supplied by a 25kV utility substation. The grading drawings for the plant suggest that the backfill material is ‘225mm pit run gravel and 75mm thick coarse gravel layers’ for the whole plant area plus substation...

Hi everyone, While working with a 36/25kV 25MVA power transformer, I came across something labelled as a 'core bushing terminal'. Is this a grounding connector for the transformer core? I've never came across this before. Can someone please clarify its purpose? Thanks

Thanks alot that was very helpful. A closer look at both connectors shows that sliding connectors usually have a ring to enable tubular bus to slide freely whereas expansion connectors have flexible wire strands to ensure electrical connections as distinct tubular sections expand/contract.

Hi everyone, I have a question about bus connectors used in high voltage substations. There are mainly 3 types; fixed connectors, expansion and slide connectors. Whereas some connectors manufacturers use the term expansion and slide interchangeably, is there really any difference between them...

Hi everyone, Just wondering what is the difference between substation clamps and conductors? Are there terms used interchangeably ?? Thanks,