A number of organisations across the UK recommend a standard earthing design when building smaller scale substations. The key driver behind these is one of cost. Nobody wants to pay more than they have to. So, the question is — does installing a standard earthing design meet your obligations under the Electricity at Work regulations? Precautions shall be taken, either by earthing or by other suitable means, to prevent danger arising when any conductor other than a circuit conductor which may reasonably foreseeably become charged as a result of either the use of a system , or a fault in a system , becomes so charged; and, for the purposes of ensuring compliance with this regulation, a conductor shall be regarded as earthed when it is connected to the general mass of earth by conductors of sufficient strength and current-carrying capability to discharge electrical energy to earth. In my opinion, the key part of this extract is the last phrase: i.
|Published (Last):||22 June 2013|
|PDF File Size:||2.92 Mb|
|ePub File Size:||1.46 Mb|
|Price:||Free* [*Free Regsitration Required]|
The New ENA earthing standards have finally arrived after a very lengthy consultation process. For those of you not too familiar with this standard, it is used to calculate the earth grid impedance, earth potential rise and associated touch and step voltages, during a phase-earth fault on an HV electrical network.
The update is long overdue, and whilst the older standards were very good, they were rather dated in some areas. This results in a much more streamlined and practical standard, with some helpful new criteria and assessment procedures.
Whilst the latter approach is always best for larger projects, it is often not viable for smaller 11kV sites. We will add some further detail about the standards when we have chance, so please check back soon! SPE are usually busy working for our customers, but when we get chance we like to write useful technical articles on PowerSystems to help developers and clients. Please look at our Technical News page, for the latest articles prepared by our engineers.
Alternatively please have a look at our Case Studies page, to see some […]. At a practical level, what does this mean for earthing designers, operators and ICPs? There are a few key major differences: Lots of updated pictures, and scenarios. There is a very useful practical flow chart for deciding on the design route that must be followed see below.
Global earthing is now an accepted approach — this will be very useful for smaller substations in urban environments, and may avoid the need for detailed CDEGS modelling if certain criteria are met. Practically the new criteria are very similar to the old guidelines though! The safe touch and step voltages have been updated and revised for a variety of different protection clearing times.
The step voltage limits are now much higher, and tolerable step limits are much less likely to be a be problem unless it is a sensitive site. More practical guidance is given in terms of separation between HV earthing systems and other buried services and buildings. It is now generally regarded that use of earthing software is necessary for all but the most simple of cases.
ENA TS 41-24 and S34 – Earthing Standard For Earth Potential Rise Calculations
Your Standard Earthing Design – Are They Valid Anymore?