Schneider Electric says some kinds of GFCI breakers are not backfeed
friendly and can in fact damage them:
http://static.schneider-electric.us/docs/Circuit%20Protection/0900DB1001.pdf
---start quote---
These circuit breakers are distinctive in that they have a white
“pigtail” wire intended for connection to the neutral bar in the
panelboard in which they are installed. This pigtail wire not only
completes the branch circuit (the neutral wire must be connected to the
circuit breaker rather than to the neutral bar), but also completes the
power supply circuit for the electronic ground fault detection circuitry.
Backfeeding (reverse connecting) these circuit breakers will result in
damaging the trip solenoid, rendering the ground fault trip function
inoperative. For this reason the terminals on these circuit breakers are
marked “line” and “load”.
---end quote---
---start quote---
In summary, circuit breakers with ground fault protection that is line
powered, such as those with a pigtail connection, are not suitable for
backfeeding. The terminals on these circuit breakers are clearly marked
“line” and “load”. This includes Square D™ QO™ and Homeline™ circuit
breakers with GFCI (5 mA) and QO and Homeline circuit breakers with low
level GFPE (30 mA) protection.
Circuit breakers with ground fault protection that is fault powered,
such as larger molded case, insulated case and low voltage power circuit
breakers, may be suitable for backfeeding. If they are, their terminals
will not be marked “line” and “load”. All Square D PowerPact™ and
Masterpact™ circuit breakers with Micrologic™ electronic trip units are
suitable for backfeeding.
Square D add-on ground-fault modules for PowerPact H- and J-frame molded
case circuit breakers are also suitable for backfeeding.
Square D add-on earth-leakage modules for PowerPact H- and J-frame
molded case circuit breakers are not suitable for backfeeding as they
are line-powered devices. The OFF end terminals on these modules are
marked “load”.
---end quote---
On 06/06/2014 01:32 PM, Cor van de Water via EV wrote:
GFCI has no influence on backfeeding, except when a ground fault
triggers it and it disconnects.
I agree that L1 power is sufficient for charging EVs most of the time
(I am 99.9% L1 charge user)
My only concern is if the grid support can be delivered through L1,
in other words - can an EV give a meaningful support to the grid if it
is limited to 1.5kW?
The other concern is that most L1 outlets are shared (I mean: more
outlets on the same circuit breaker) whereas a backfeeding generator
preferably is on its own breaker to avoid that you can draw power power
from the *other* outlets than that the breaker is protecting - there is
a small risk of burning up the wires without the breaker triggering if
the backfeeder if giving a steady stream of power (most notably this
occurs with solar, that is why an inverter is typically always on a
separate circuit with no other loads connected to the same circuit).
Since I have no clue about the typical power levels involved with grid
stabilization, I leave my first concern unanswered - hopefully someone
else can contrtribute meaningfully to that one.
Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626
-----Original Message-----
From: EV [mailto:[email protected]] On Behalf Of Haudy Kazemi
via EV
Sent: Friday, June 06, 2014 10:44 AM
To: Robert E CIV USNA Annapolis Bruninga; Electric Vehicle Discussion
List
Subject: Re: [EVDL] V2G at L1 is practical
On 06/06/2014 09:41 AM, Robert E CIV USNA Annapolis Bruninga via EV
wrote:
Subj was: RE: [EVDL] EVLN: E-school-buses$aveschooldistrictsmillions
I just think the fluctuation in loads is substantially more
predictable
than the number of vehicles plugged in at any one time.
Which trigger my 2 cents:
V2G will never be practical unless vehicles are plugged in all day.
And if they are pluggedin all day, then they only need 120v L1 15 amp
service.
Already, we know that 97% of charging-at-work is satisfied with L1
charging.
So in order for V2G to be able to take advantage of all the
demand-load of
millions of EV's and/or to also take some charge, the focus has to be
on
low-cost L1 approach, not expecting EVERY EV (by the millions) to have
a 50
amp L2 service and to sit there blocking it all day long. That is
simply
unsustainable at the quantities needed. Millions of L1 outlets is
possible
and practical.
But providing at least demand-response at every L1 outlet in a parking
lot
is as easy as hooking up a water-heater or Airconditioner utility
disconnect
and giving the utility immediate control over that load during the
day.
This is not only dirt cheap, and practical, it eliminates the #1 issue
with
V2G (NFMB, Not From MY Battery!).
Sure it gives up 50% of the promise of V2G (and all its NFMB issues)
but the
other 50% is the low hanging fruit, that is PRACTICAL at SCALE is
simply L1
charging-at-work with demand response control of the outlets.
Bob Bruninga, PE
EVADC
V2G is a type of backfeeding; 120v L1 outlets protected by GFCIs
probably won't work very well for this, but dedicated 120v outlets
exempt from upstream GFCI could.
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