Onsite-substations

depends, is the answer

you will get better rates if you buy the electricity at 11kV and own your own transformer and ring main unit. 

Can be either.

Sometimes the DNO provide an HV supply, often at 11 KV, and providing and maintaining the substation is then a customer problem. In such a case a slightly low tariff is generally applicable since the losses in the transformer are now paid for by the customer. In this case the customer, or their appointed HV person/contractor will have keys to the substation which should be kept locked.  The keys should be kept secure but quickly available to the authorised person.

Sometimes the substation is DNO property but happens to be sited on, or adjacent to, or within customer owned property. For a substantial load, the DNO may require that space for a substation be  provided. In this case the customer should NOT have keys to the substation.

In this cases the customers responsibilities are limited to keeping the access clear, and reporting any problems such as flooding that has entered or is likely to enter the substation.

If the customer DOES have keys, then enquiries should be made as to whether this is correct, or a mistake.

As well as broadgage’s comments, it also means that the DNO won’t bring a new one free of charge, if it fails. If it is not one of the standard ESI spec units, it may not be an “off the shelf” replacement. 

Regards,

Alan. 

Metering may then be at HV - as noted in such a case losses are the customer problem.

The other advantage of metering at HV is that losses are reduced, at least on paper. The DNO can now say, “losses in our network are falling year on year”

The transformer losses still occur of course, but are now part “of customer consumption” rather than being “DNO network losses”

my place of work thought that the DNO owned the transformer on site, however, when i started, i did some investigation work and found that we did indeed own it, and then immediately had to appoint an HV qualified company, our last inspection revealed a major potential problem with it and we are replacing it at Christmas, this has given us the opportunity of reducing the size of the transformer from 1600KVA to 1MVA, and putting in an amorphous core super low loss one, which should see our bills drop through the floor, as the landlord also wants to put PV on the roof!

“reducing the size of the transformer from 1600KVA to 1MVA” ?

grubbym: 
 

my place of work thought that the DNO owned the transformer on site, however, when i started, i did some investigation work and found that we did indeed own it, and then immediately had to appoint an HV qualified company, our last inspection revealed a major potential problem with it and we are replacing it at Christmas, this has given us the opportunity of reducing the size of the transformer from 1600KVA to 1MVA, and putting in an amorphous core super low loss one, which should see our bills drop through the floor, as the landlord also wants to put PV on the roof!

thats the bit I cant find any regs on, appointing a qualified company/person

We have a “Joint Operational Agreement” where we sell a supply at HV, which lists the ownership and responsibilities. Part of the agreement is related to what the customer has to provide in the way of Authorised Persone. 

Regards,

Alan. 

the harpist is harping, and I'm remembering

I took a call from the DNO, who, after a year of going 11kV, were enquiring if I was appointing my own person/company, or wanted to pay for them to do it for another year. 

I think the gist was that they included 1 year of appointed person, then it was over to us.