• Skip to main content
  • Skip to primary sidebar
  • Skip to footer

GreyMatters

Electrical Earthing System Design & Soil Resistivity Testing

  • Home
  • About
    • Contact Us
  • Blog
  • Earthing Services
    • Earthing Design Services
    • Lightning Protection Design
  • Earthing Training Courses
  • XGSLab
    • XGSLab Services
    • XGSLab Online Demo
    • XGSLab Sales
  • Members Academy
Home » Ask the Experts Electrical Earthing Blog » 50 Shades Darker – CDEGS Myths Busted!

26/03/2015 By Ian Leave a Comment

50 Shades Darker – CDEGS Myths Busted!

CDEGS Modelling Software demystified!

It’s interesting how the psychology of the car has found a place in our daily lives.  How many times have you asked or been asked ‘what car do you drive?’

If you’re one of the lucky few that own a Ferrari (unfortunately, I am not one of those!) – you might receive a different response than if you own a Nissan Micra.  The common thread is that there are both ‘cars’ aimed to transport you from A to B – but each one has been designed, developed and delivered to fit two very different budgets and to two very different purposes.

When to ask for black or white – not all CDEGS Modelling Software are the same!

 

CDEGS Modelling Software Demystified

In the land of cars, we measure performance in terms of acceleration (0-60 MPH), top speed, economy (MPG), ecology (g/CO2) or lap times if you’re a Top Gear fan …

In Earthing – the key performance measures (for EN 50522, 50122-1) are a function of accuracy % error, complexity, and/or correlation to reality.  The trouble is, one of the best-kept secrets is that different versions of “CDEGS Modelling Software” also exist – From the £7,000 Nissan Micra to the £200,000 Ferrari 488.

So, next time you receive a fee proposal for an Earthing Study that claims to be CDEGS compliant – ask the provider ‘what version/module of the CDEGS Modelling Software are you intending to use?’ Why (you might ask)?

The chief reason boils down to the engine that powers the modules – some modules, like MALT and MALZ rely on ‘Circuit Theory’.  Others, such as HI-FREQ are based in ‘Electromagnetic Field Theory’.

Why does this matter?

Two words … ERROR RATE.   If your application is on the simpler, smaller end of the earth design spectrum, with lower fault energisation levels; then the more budget sensitive versions of the CDEGS  Modelling Software which are based in Circuit Theory may be sufficient… but as the complexity and/or the size increases, so will the rate of error increases – sometimes as much as 50%.

Think about it – let’s say there’s a 6 kA fault with a 50% split factor.  This means there’s 3 kA going through the Main Earth System to earth.  For ease of calculation, let’s assume the Earth is 1 Ω impedance, which means the basic Earth Potential Rise (EPR) for the system should be around the 3 kV mark.

But what if the software module selected has underestimated the EPR by 50%?  This would lead to a 1.5 kV difference in predicted verses actual – is this significant??

I accept in this scenario mentioned, it’s not possible to be definitive without understanding a bit more about the circumstances but taking this at face value, an underestimate of 1.5 kV could have a significant impact on the touch/step safety – without putting too fine a point on it, enough to kill.

So, an upgrade in the computational engine is required for the larger, longer, more commonly encountered earth designs or studies for ‘power systems’, which can take account of mutual coupling effects, inductance, capacitance, e.g. the calculations are not limited to just the conductive/resistive effects.

Armed with an Electromagnetic Field Theory engine, the risk of error is mitigated – typically by an order of magnitude lower, which means we can all sleep at night because the design is using robust, accurate, low levels of error, based in the latest accepted science for its calculations.

If you have a ‘critical’ asset or infrastructure project – then the standard requirement has to be the elimination (or reduction at least) of error that can be easily avoided.  In most cases, this can be achieved by simply being more aware of the choices available and the residual risk in the modules used.  Knowingly or otherwise, no-one wants to be haunted by easily avoidable errors.

There’s a bewildering quantity of CDEGS modelling software modules – so if you’re not sure whether what is being used on your project is fit for purpose – drop us a line on our live chat facility below … for a super quick response.

Featured Image:  LaFerrari

 

Software Tools Update – Jan 2020

Regular readers of this blog will know GreyMatters have championed CDEGS for many years. But now there is a viable and attractive alternative to CDEGS. I explain “Why I chose this alternative” in this article. And compare several past projects, done with CDEGS and the alternative – in this article.

Filed Under: CDEGS Tagged With: 50122-1, BS7430, CDEGS, earth electrode, earth systems, Earthing, earthing design, Electromagnetic Field Theory, electromagnetic interference, EMF, EMI, EN 50522, greymatters, HI-FREQ, MALT, MALZ, safety earth, soil structure

Electrical Earthing Training – Free Trial

Do you want to understand more about Electrical Earthing System Design – Greymatters Academy is our Earthing Training site take a look or access your free trial here.

Recent Posts:

retractable grounding assembly

We take a look at the risks associated with ATEX/COMAH sites and what the ATEX-approved patented Retractable Grounding Assembly (RGA) does to reduce the risk of tank fires by subduing sustained arcs during the lightning event and other electrical phenomena. If you missed it, you can watch a replay of the webinar here.

Understanding the risks of EMF

Impressed voltages and interference from electromagnetic fields are increasingly becoming a hot topic for safety professionals and engineers alike. Hugh looks at the risks of EMFs, when you need to do an EMF study and how XGSLab does the heavy lifting for you when doing EMF studies. Watch a replay of the webinar here. Ian: […]

Earthing in difficult geologies

Ian takes us on a recap of earthing in difficult geologies, you can find the webinar replay here. Ian: Hello and welcome. How many times have we faced with the install team, or you are doing tests on site. You come back, and the readings are high, far higher than expected, and you are scratching […]

Why is a hot site a problem

Hugh takes us on a deeper dive into hot sites and answers the question ‘Why is a hot site a problem?’ You can find the webinar replay here. Hugh: Hello, everyone, thanks for joining our webinar this morning. This is a continuation from our previous session where Ian introduced the concept of a hot site […]

why am I getting a hot site?

Hello, and welcome this month’s topic, Ian answers the question Why am I getting a hot site? You can find the webinar replay here. Now for those that know me, I like to start these sessions with a thought of a concept that I’ve come across over the week. This is another one from James […]

About Ian

This post is written by Ian Griffiths, Principal Engineer at GreyMatters, an Earthing & Lightning Consultant of 28 years, one of the top 1% accredited CDEGS and XGSLab consultants and professional advisor to international utility companies, data centre and infrastructure developers.

Reader Interactions

Leave a Reply Cancel reply

You must be logged in to post a comment.

Primary Sidebar

Online Earthing Courses

Free Trial Learn More

Free Online Course – Learn Ohms Law in 10 minutes or less!

Learn Ohms Law

Our Top Earthing Post

Electrical Fault Theory

Blog Categories

  • Acadamy (2)
  • Anti-Theft (1)
  • CDEGS (5)
  • Earth Testing (6)
  • Earthing Designs (5)
  • Earthing System Design (16)
  • Earthing Systems (4)
  • Electrical Earthing (34)
  • General Post (9)
  • Grounding (1)
  • Lightning (8)
  • Lightning Protection Design (15)
  • Lightning Strike (1)
  • Renewable Energy (2)
  • Soil Resistivity (17)
  • Soil Resistivity Testing (10)
  • Solar (3)
  • XGSLab Updates (2)

Tag Cloud

BS7430 BS EN 50522 CDEGS data centres earth electrode Earthing earthing design earthing protection earthing standards Earthing system design earthing systems earth potential rise earth systems Electrical Earthing System Design Electromagnetic Field Theory electromagnetic interference EMI EN 50522 EPR Finite Element Analysis Finite Element Analysis Software greymatters Grounding HV Earthing HV Earthing Protection lightning lightning danger Lightning Protection lightning strikes Renewable Energy Rise of Earth Potential risk management ROEP Soil Resistivity Soil Resistivity Methods Soil Resistivity Testing Soil Resistivity Testing 10 Common Mistakes Soil Resistivity Testing Methods soil structure Step Potential Surge Protection Tag Archive - Lightning Strike Touch Potential what to do in a thunderstorm what to do when lightning strikes

Footer

  • Terms
  • Privacy
  • Cookies

Copyright GreyMatters © 2022