Discuss Interconnection of MV Earth with LV Earth in Public Supply in the UK Electrical Forum area at ElectriciansForums.net
HV,LV whats MV? thought MV was old hat.What factors determine the interconnection of the MV neutral/earth with the LV neutral at the local substation? When are they connected together and when would it be appropriate not to connect them together?
NopeHV,LV whats MV? thought MV was old hat.
wheres does MV Start and HV kick in? and where does it state the parameters ?Nope
ELV, LV, MV, HV, EHV etc all still very well defined.
it is only the wiring regs that simplifies everything above LV as "HV"
I thought MV was 1-33kVwheres does MV Start and HV kick in? and where does it state the parameters ?
Iec 60071 defines MV as 1kV to 36kVwheres does MV Start and HV kick in? and where does it state the parameters ?
Oops, yes 275, got mixed up with some other work - must pay better attention.Most power distibution is at 132kv (highest voltage for a DNO), 275kv and 400kv. I've never seen or heard of 232kv.
At EHV you don't have to worry about touching a live conductor. You would be dead well before you touched anything. NG safety distances are 1.4m at 132kv, 2.4m at 275 and 3.1m at 400kv but in reality it's 'as far away as f'in possible'.I'm assuming they are phase-neutral (i.e. earth) since the main risk of shock is touching a line conductor while in contact with the Earth (or attached parts)
A reasonably quick way to tell the voltage of a pylon. If it's just got 1 cable per phase it's 132kv. 2 cables is 275kv and 3 or 4 is 400kv.Most power distibution is at 132kv (highest voltage for a DNO), 275kv and 400kv. I've never seen or heard of 232kv.
And next comes UHV.Iec 60071 defines MV as 1kV to 36kV
Most others take the value as 35kV (such as iec60038)
HV is 35kV to 230kV
EHV >230kV
Unless you're not on the ground...At EHV you don't have to worry about touching a live conductor. You would be dead well before you touched anything.
Interesting stuff,
I thought HV power distribution was delta, so no neutral (star point)
I have no basis for this, other than my own conclusion from looking at 3 wire overhead lines, going to what i presumed were delta to star transformers to step voltage down to 230v (415v) and provide a neutral / earth for consumers??
Nope, the same, I have had little to do with transmission stuff in a practical sense.I wouldn't do that job for any money! I wouldn't climb the pylons either. I'm happy when I'm just climbing about all over the transformers ?
LV networks are always solidly earthed and may be TT TNS or TNC-S.Does the grounding at the HV-MV substation play any role? I've heard that MV systems in the UK are resistance or peterson coil earthed. Is this true?
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