[SystemSafety] Hazard and Qualitative-Risk Analysis of Mode 3 Charging of Electric Road Vehicles

Peter Bernard Ladkin ladkin at rvs.uni-bielefeld.de
Tue Oct 22 11:32:53 CEST 2013


On 10/21/13 5:07 PM, Andrew Rae wrote:
> The only comment I can make until the document is in English is to applaud you and the committee for
> opening it to public peer review.

Thank you!

My personal wish is that such an analysis be public, and be improved and filled out as experience is
gained. Because lots of people have an interest in ensuring that such processes are as safe as can be.

The house stuff worries me. Some people have been explaining the state of electrical installations
in buildings in Germany. It is not much different from other countries and, we may presume, better
than most. There is no requirement to modify installations in private households, although when
professional electricians are called in, they upgrade the circuits with which they deal to current
standards, and advise on the rest if necessary.

The different standards throughout Europe along are .... interesting. Almost everyone has protection
against excessive current and short-circuits (these are two different kinds of protective device,
even though a short-circuit mostly results in excessive current). But requirements for residual
current devices vary. The British, and I think the French, require only Type AC, which protects
against a sinusoidal wave form, but not against modified sinusoidal wave forms (say, those where
half the cycle is chopped to null). Those are protected with Type A devices (a Siemens
specification) which is since 2007 the law in Germany (my house protection was modified in 2006, but
has them in - it has been state of the art for a while. The protectors are combined
excess/short-circuit/Type A RCD devices to an Eaton design). Type A protection, though, may be
blinded by DC currents of 6mA or over. There is quite a lot of discussion about that in
standardisation committees at the moment, because electric vehicles have DC circuits in them and the
question is where the protection should occur. Type B RCDs protect against all RC, but Type A
combined protectors cost about €30 and Type B well over €100. Not much difference, one might think,
but in practice it means that people and companies don't install Type B protection if they can avoid
it.

What we are really concerned about is people putting in their own recharging boxes. These things
deliver a lot of juice over many hours, potentially daily. The boxes themselves *should* be
installed by a professional electrician who has the responsibility to ensure the circuit at the back
of it is fit for purpose. But when heshe comes into the building and says "oh, my, you need
this-and-this-and-this in the way of a circuit behind your box and it'll cost €€€€€€€" then some
building owners may well think "gee, I'll just put it in myself and avoid all that". That's folks.

15 or 16 people die in Germany every year from electric shock from building circuits. About 600
people die in building fires, of which fully one-third derive from electrical faults. So roughly
speaking ten to thirteen times as many people die from electrically-caused fires as directly from
electric shock. Nevertheless, in our analysis we rate shock as a more severe outcome than fire,
because shock is instant and one has a chance theoretically to take some action in case of fire.

None of that gets into the HazAn, but it is stuff we think about in Committee a lot. Indeed, there
is one project in my uni group (a Master's thesis) trying to assess reliably the state of
installations in a small town near Bielefeld, and we have a project application in to try to do it
for Bielefeld. We shall have to work with social scientists who know how to do this kind of thing.

> I don't know the direction of cause and effect but the difference in quality between open and closed
> risk assessments in my collection is marked. This doesn't stop a prevailing culture of secrecy.

When risks are assessed by a company for a product, or a systems integrator, then that entity is
responsible in a legal sense for that analysis. If that analysis is open and if/when an accident
happens then the legleagles have immediate access to an analysis they can criticise. If the analysis
is not available, then there are all sorts of legal processes one might have to go through to obtain
it; wide-ranging US-type disclosure rules do not apply over here, as I understand it; our rules are
more limited.

> I look forward to the English version, and I hope you will consider publishing the received comments
> to the extent permitted by confidentiality.

That is strictly up to the authors of the comments. We also consider publishing comments anonymously.

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de






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