I agree with you 100% about your design approach with relays. I took the same
approach. I see the same issues with out sourced and China designs. In
addition, US management has said to their engineering staff, if they can do it
then you do it. I fought this battle at numerous design reviews. Therefore, I
am not surprised that this Smart Fortwo? burn to a crisp. As far as UL, UL is
not what they used to be. Things changed when the US changed to NRTLs. In
order to compete for business, the labs have gotten cozy with businesses.
From: Lee Hart <leeah...@earthlink.net>
Sent: Wednesday, July 12, 2017 2:28 PM
Subject: Re: [EVDL] ? Is this really a Smart Fortwo ED EV that burnt to acrisp ?
> Lee, you are correct. I agree; however, I would never use a relay on an EVSE.
> But that just me. I have a motor control (with correct size heater) on my
> outside fountain pump (1/6 HP).
All I can say is that both Nissan and Toyota used relays in their 120vac EVSEs,
and both are UL listed. That means they satisfied UL that they are safe.
I worked for Robertshaw and Honeywell for well over a decade, designing controls
for large home appliances and furnaces. In all but the highest power ones, we
But they weren't your run-of-the-mill cheap relays; they were ones with a long
list of safety approvals and testing. And, we often had backup systems in place
to detect a welded relay contact and stop operation some other way. For example,
TWO relays in series, with logic that tested each one individually before
closing both to energize the load.
One thing that saddens me is that large amount of such "intrinsically safe"
design has gone out the window as companies weaken the regulations and outsource
everything to countries where safety testing is weak or nonexistent.
Manufacturers now get controls from China that do things that would NEVER be
tolerated in a US product.
Where ignorance is our master, there is no possibility of real peace.
-- Dalai Lama
Lee Hart, 814 8th Ave N, Sartell MN 56377,
The Sunrise EV2 Project<http://www.sunrise-ev.com/>
The Sunrise EV2 Project Homepage. Welcome! We are a group of dedicated electric
vehicle enthusiasts whose goal is to create an affordable, high performance
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