Electrical code Compliance - What voltage gives 1 cm spark in air?

Author

What voltage gives 1 cm spark in air?

Martin Leese

2005-10-22, 2:21 pm

Hi,

We are in Canada and starting to look at IEC 6001-4-2
compliance to sell into Europe. One product failed
its spark discharge test. We don't have US$2500 to
spend on an ESD gun, so we replicated the problem
using a piezoelectric barbecue lighter. (I then got
a little too enthusiastic and fried the motherboard
on my PC. However, the new motherboard was only
$200, so we are still ahead.)

We now want to know what sort of voltage the barbecue
lighter is putting out. It can generate spark as big
as 1 cm in air. Approximately what voltage is needed
to do that? The barbecue lighter can typically
generates a 0.5 cm spark. Would that voltage be
half?

Many thanks,
Martin Leese
E-mail: please@see.Web.for.e-mail.INVALID
Web: http://members.tripod.com/martin_leese/

Andrew Gabriel

2005-10-22, 4:21 pm

In article <djdptg$28g$1@news.ucalgary.ca>,
Martin Leese <please@see.Web.for.e-mail.INVALID> writes:
> We now want to know what sort of voltage the barbecue
> lighter is putting out. It can generate spark as big
> as 1 cm in air. Approximately what voltage is needed
> to do that? The barbecue lighter can typically
> generates a 0.5 cm spark. Would that voltage be
> half?

It depends on lots of things. A rough guide is 25kV/cm
will break down, whereas 25kV/inch is a minimum insulation
distance.

Given the short duration pulse nature of the piezoelectric
lighter, breakdown within that time probably requires a
significantly higher voltage than the rough 25kV/cm, so I
would guess 25-50kV for your 0.5cm to 1cm sparks.

--
Andrew Gabriel

hrhofmann@att.net

2005-10-24, 12:21 am

Martin Leese wrote:
> Hi,
>
> We are in Canada and starting to look at IEC 6001-4-2
> compliance to sell into Europe. One product failed
> its spark discharge test. We don't have US$2500 to
> spend on an ESD gun, so we replicated the problem
> using a piezoelectric barbecue lighter. (I then got
> a little too enthusiastic and fried the motherboard
> on my PC. However, the new motherboard was only
> $200, so we are still ahead.)
>
> We now want to know what sort of voltage the barbecue
> lighter is putting out. It can generate spark as big
> as 1 cm in air. Approximately what voltage is needed
> to do that? The barbecue lighter can typically
> generates a 0.5 cm spark. Would that voltage be
> half?
>
> Many thanks,
> Martin Leese
> E-mail: please@see.Web.for.e-mail.INVALID
> Web: http://members.tripod.com/martin_leese/

Why not rent an ESD gun. Also, you better do a lot of studying on ESD.
There is an ESD Association that has lots of free information. But,
you will have to buy the EN/IEC standards. That's why going to test
houses and paying for their expertise is cheaper for producers of small
low-volume products than buying all the equipment, standards documents,
and time=$$$.

H. R.(Bob) Hofmann

Martin Leese

2005-10-26, 1:21 am

hrhofmann@att.net wrote:

> Why not rent an ESD gun. Also, you better do a lot of studying on ESD.
> There is an ESD Association that has lots of free information. But,
> you will have to buy the EN/IEC standards. That's why going to test
> houses and paying for their expertise is cheaper for producers of small
> low-volume products than buying all the equipment, standards documents,
> and time=$$$.

A European distributor is having the formal tests
done, so they are paying the test house. One
product failed, and it was not a product that we
expected to fail.

We needed to replicate the failure in-house so
that we could investigate it and work out how to
overcome it. The barbecue lighter works really
well for this; it would be foolish to rent or buy
anything more sophisticated at the moment.

Thanks for the advice anyway.

--
Regards,
Martin Leese
E-mail: please@see.Web.for.e-mail.INVALID
Web: http://members.tripod.com/martin_leese/

operator jay

2005-10-27, 10:21 am

"Martin Leese" <please@see.Web.for.e-mail.INVALID> wrote in message
news:djdptg$28g$1@news.ucalgary.ca...
> Hi,
>
> We are in Canada and starting to look at IEC 6001-4-2
> compliance to sell into Europe. One product failed
> its spark discharge test. We don't have US$2500 to
> spend on an ESD gun, so we replicated the problem
> using a piezoelectric barbecue lighter. (I then got
> a little too enthusiastic and fried the motherboard
> on my PC. However, the new motherboard was only
> $200, so we are still ahead.)
>
> We now want to know what sort of voltage the barbecue
> lighter is putting out. It can generate spark as big
> as 1 cm in air. Approximately what voltage is needed
> to do that? The barbecue lighter can typically
> generates a 0.5 cm spark. Would that voltage be
> half?
>
> Many thanks,
> Martin Leese
> E-mail: please@see.Web.for.e-mail.INVALID
> Web: http://members.tripod.com/martin_leese/

I generally think of it as 1kV per mm, maybe 3kV per mm. But it's not
important to me, so I don't have a good source.

http://www.google.ca/search?hl=en&q...eakdown+voltage
http://www.allaboutcircuits.com/vol_1/chpt_12/8.html
http://www.ce-mag.com/archive/02/01/MrStatic.html
etc.

j

Esa Häkkinen

2005-10-29, 4:21 pm

operator jay wrote:
> "Martin Leese" <please@see.Web.for.e-mail.INVALID> wrote in message
> news:djdptg$28g$1@news.ucalgary.ca...
>
>
>
> I generally think of it as 1kV per mm, maybe 3kV per mm. But it's not
> important to me, so I don't have a good source.
>
> http://www.google.ca/search?hl=en&q...eakdown+voltage
> http://www.allaboutcircuits.com/vol_1/chpt_12/8.html
> http://www.ce-mag.com/archive/02/01/MrStatic.html
> etc.
>
> j
>
>

It's really around 3kV/mm, which is about 25...40kV/cm. You can check
the value from ignitor of a normal gasoline operated engines, like
grassmover or car engine...

And this 3kV/mm is in Normal Temperature Pressure NTP, and humidity
around 50%. At larger pressures value rises, because there are more
molecules of Nitrogen/Carbondioxide between connectors. At lower
humidity like in wintertime, below <40%, the number of sparking effects
increases with even normal clothing. You can create 100kV just getting
up from a plastic summerchair.

And the ways on defending against these electric potential differences
between interface pins, you might want to make a simple "two nails"
-solution, like just keeping plain metal pins sitting at device's power
input groud 1mm away from each input's similar ones. Then You might have
a chance of eliminating these potentional differences between interface
pins just discharging A-pin thru PowerGND thru B-pin.

You must make sure, that these "nails" are not coated with any plastic
or similar PCB protections spray.

That's my '50cnt

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