HV System Grounding

[speedtronic]

Why HV system are normaly not grounded through some impedance, I mean why are they solidly grounded? I am refering to power transformers actually, normaly their HV side is grounded solidly & not through some impedance where as MV equipments like alternators neutral is grounded through a transformer?

 

[ian.settle1]

Why HV system are normaly not grounded through some impedance, I mean why are they solidly grounded? I am refering to power transformers actually, normaly their HV side is grounded solidly & not through some impedance where as MV equipments like alternators neutral is grounded through a transformer?

Don't quite understand what your asking as in the UK anything AC upto 1000v is classified as Low voltage and anything above is High voltage.

When equipment is earthed it is normallt direct to earth and not via a tranny.

 

[speedtronic]

In my case, consider HV above 40 KV & MV from 1KV to 40 KV while LV below 1 KV. This is the understanding atleast in Middle east & Asia (I think). Now what I have seen that nuetral of turbo generators (MV equipment) is normaly grounded through some impedance but thats not the case normaly with HV equipment like transformers, their neutral on HV side is normaly solidly grounded i.e. without any impedance. Why?

 

[mechelec]

11KV systems and above have NER in UK. Check this link hopefull it should help

http://www.eon-uk.com/distribution/...ication Guide Primary Neutral Earthing v2.pdf

 

[NoSparks]

THIS IS PURE GUESS WORK!!!!!!!!!!

The small resistance to earth may help limit the current flow in the event of an earth fault.

The voltage across this resistance could be used to detect an earth fault and cut out the supply.

PS isn't this the fundamental definition of an IT system (which is not approved for use in the UK)

 

[mechelec]

THIS IS PURE GUESS WORK!!!!!!!!!!

The small resistance to earth may help limit the current flow in the event of an earth fault.

The voltage across this resistance could be used to detect an earth fault and cut out the supply.

PS isn't this the fundamental definition of an IT system (which is not approved for use in the UK)

I think you are missing the point that this is relating to electrical distribution which is a totally different set of rules to BS7671. Any distribution transformer with a secondary of 11 or 33KV will have the neutral star point connected to earth via a resistor.

 

[chlee-penang]

I noticed the plant I worked previously, 33KV/11KV transformer Start Point (Neutral) earthed via resistance, likewise the 11KV generator is also earthed through a neutral resistance to limit earth fault current.

 

[GMES]

The thread is 5 years old so time to close it thanks guys.