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26th Oct 2020 Login  
G5/9 @ 33kV
by Tony Noble at 2010-12-21 10:43:48 (Ask an Expert)
Does anybody have any info I could research, on the net, for the above application?
I am looking to understand the 'hoops' that have to be jumped through in order to get an export connection at 33kV.

I have very little experience of this element, of electrical engineering, but have done normal import 33kV grid connections before.

Thanks in advance for any help and assistance.

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G5/9 @ 33kV Tony Noble - 2010-12-21 10:43:48
Re: G5/9 @ 33kV Bryan Rendall - 2010-12-21 14:03:09

As an NERS accredited contractor for both 11 and 33 kV, we have done a lot of work on these connections for windpower, ranging from large windfarms down to single turbines.

There is a significant amount of work to do for a 33 kV connection, more than can be detailed in a posting on here. However, as you have knowledge of 33 kV import connections, we can skip over most of the issues (which are common to import and export), and cut straight to your title, which I assume is G59.

G59 protection can be implemented either at the substation, or at the turbines. We favour the turbines, executing a stop command, as opposed to tripping the 33 kV breaker, forcing the turbine into an emergency stop situation. Either can be, and have been accepted by the DNO's

G59 equipment needs to be witness tested by the DNO to their satisfaction, and this involves using a 3 phase injection test set to inject the relay with the variable voltage, frequency and rate of change of frequency.

There may well be other considerations that are different from import connections, namely P28 and G5/4, whereupon you would need to assess the impact on voltage and harmonics from your proposed generation.

As each connection tends to be site specific, then I would doubt that you will find a simple guide on the net. You could however start off by getting a copy of G59/2, G75, P28 and G5/4 from the ENA and have a good read up there for an idea of the general principles.

Otherwise, designing a 33 kV generation connection at 33 kV involves a great many man-weeks of works, and I would run out of characters here!


Bryan Rendall

Re: G5/9 @ 33kV Tony Noble - 2010-12-30 19:17:04
Thanks very much for the info. I was aware that there was a lot involved, just didn't know where to begin the research.
I will be reviewing the documents you have highlighted as a starting point.
Out of interest what is an NERS accreditted contractor?

Thanks again for your help and assistance.


Re: G5/9 @ 33kV Bryan Rendall - 2010-12-31 10:10:59
Hi Tony,

An NERS Accredited contractor is one who has been assessed by Lloyds Register under NERS (National Electricity Registration Scheme).


This is the requirement of all UK DNO's for contractors carrying out contestable works. DNO's will not accept contestable works carried out by non accredited contractors.


Bryan Rendall

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