Hi Lee,
Part of the long, long discussion covers this. We have a list of common
metal items (along with size and material) that must be detected. There
are some other standards that EV charging will have to conform to, since
we will need to prevent overheating that can cause human injury.
Some of the scenarios that we have:
* metal left on the pad before charging (coins, cans, keys, metal
foil, etc),
* metal blowing onto the pad during charging (same list),
* living objects moving near to the charging area.
The list is not complete yet, but I'm hoping we'll be done with it by
the end of the year. It is slow going since we need to negotiate with
companies worldwide.
Cheers, Peter
On 7/19/14, 8:53 AM, Lee Hart via EV wrote:
Peter C. Thompson via EV wrote:
I've just spent an entire week working with the standard
responsible for this, so all of this is VERY fresh in my mind. :)
Excellent! I'm delighted to see your company thinks it is important.
Though, I still worry about "unintended consequences".
When I was working with a high-power switchmode power supply, one of
the techs happened to be wearing a wristwatch with a metal band. He
reached over the supply to adjust something, and his wrist watch band
got hot!
The flux leakage from the 50kw transformer was tiny -- maybe 0.1%. But
0.1% of 50kw is 50 watts -- easily enough to overheat the band. There
was no observable change in the operation of the supply at all. If he
hadn't jerked his hand away, he would have gotten burned!
I've heard of similar situations with people wearing rings or other
metal jewelry. There are also cases of burning up parts or traces on
PC boards in phones etc. due to stray EM fields. Even a tiny power
loss that's too small to detect can have serious consequences.
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