I have personally tested a number of CCS DCFCs, and NONE of them
de-energize fast enough to avoid arcing when Pilot and/or Proximity is
de-asserted. It's a tall ask to have a DCFC putting out 500 amps and 800
volts to get it to zero volts in a few milliseconds. This is why there is
a latch.
Disconnecting AC under load is NOT THE SAME. There is zero crossing 120
times a second that will help extinguish an arc, and current is over a
magnitude less. DCFC has way more current, and high voltages connected
directly to a current source that can provide tens of thousands of amps of
fault current!
On Mon, Sep 23, 2024 at 4:45 PM Bill Dube via EV <ev@lists.evdl.org> wrote:
> I should note that the connector is designed so that the pilot wire
> (communication wire) is the very first to disconnect. If the regulation
> is followed correctly, this should automatically de-energize the entire
> circuit, before the connector comes apart completely.
>
> >>>>> Locking connector rant <<<
>
> From the inception of Article 625 in the NEC, I have disdained the
> requirement that the connector(s) be of the locking type.
>
> It makes _zero_ sense to have a locking connector on a object that is
> mobile. If the vehicle moves somehow, the plug should simply disconnect
> without indecent or damage. (The vehicle parking brake is not set
> correctly. The vehicle is towed. The vehicle is accidentally hit by
> another vehicle. The vehicle is somehow placed in drive. etc....)
>
> Because the connector is locking, ("to prevent accidental disconnection"
> which is _not_ a life-threatening hazard,) if the connector is strained
> beyond its breaking point, either the cable conductors are dislodged and
> exposed, or the connector housing in the vehicle is dislodged exposing
> live conductors, or the cord is pulled out to the wall box exposing live
> conductors. If plug were to simply disconnect, like on a vacuum cleaner,
> or on an RV, then these hazards would be non-existent.
>
> As the regulation is now implemented, you have to have (expensive and
> troublesome) strain sensors on both the wall box and the vehicle
> connector housing to (hopefully) de-energize the live conductors before
> they become exposed.
>
> The mandatory requirement for a locking connector should be dropped, or
> at least made optional.
>
> >>>> Soap box mode OFF <<< 🙂
>
> Bill D.
>
> On 9/24/2024 10:53 AM, (-Phil-) via EV wrote:
> > I have discussed this here before, but neither the Lectron or the A2Z
> have
> > a proper mechanical interlock, meaning you can literally rip out the NACS
> > cable while HV is still present, which could result in an arc flashover
> > between the terminals with full pack voltage. This could generate over a
> > thousand amps of fault current and even completely destroy your EV!
> >
> > The CCS standard requires a mechanical interlock that prevents the
> removal
> > of the CCS whip while HV is present. This is enforced by a motorized
> latch
> > in the car. But there is no mechanical interlock on either of these
> > adapters, which means the connector could be removed under load! So if
> > you ever use it, please supervise it the whole time (do not leave
> > unattended!) and do not disconnect the NACS able from the adapter until
> the
> > car unlatches the adapter from the inlet, only then is it safe to remove
> > the NACS cable.
> >
> > On Mon, Sep 23, 2024 at 1:53 PM Jack Hill <jackh...@jackhill.us> wrote:
> >
> >> I'm one of the people who bought a Lectron adapter (although other than
> >> testing I may never have to use it. We'll see how long CCS1 sticks
> around
> >> I guess). Can you expand on why they're dangerous? I did read the
> report,
> >> and can't argue with the recommendations, but didn't see it call out
> >> what's specifically wrong with the Lectron adapter. Lectron's AC J3400
> >> adapter has seen years of real world use and held up fine.
> >>
> >> I'm happy to see standards. I'm kind of shocked that J3400 is being
> >> rolled out without them. It seems to me like the right order would be to
> >> do the standards first, and then a roll out (we have CCS and J1772 in
> the
> >> meantime).
> >>
> >>> Thanks for posting this, Rush!
> >> Indeed, thank you!
> >>
> >> Best,
> >> Jack
> >>
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