The "explanation" you quote doesn't make any sense to me. If the
engineer is concerned about fault current, the primary source is going
to be through the utility transformer, and it will be on the order of
5,000 - 10,000A depending on the transformer's impedance. The fault
current contribution from the inverters will be much less than that (an
SB8000 fault current is all of 61.7A) and it will last for a much
shorter duration. Be nice-- some engineers think by default that all
generation acts like a rotating machine, which can contribute quite a
bit of fault current. Not so for PV, so hopefully this engineer will see
the light with a bit of help from you.
A few questions for your engineer then:
1) These inverters will be exporting power, not drawing it; why are the
inverters not considered a negative load in this installation? [I assume
you're not installing batteries]
2) What is the "500A fault current limit" that was taken into account in
the site design? The service size is ___A.
A 167kVA transformer at 240V has a rated current of about 700A, which is
another reason why the "500A fault current" doesn't make sense.
DKC
On 2014/3/27, 15:28, Karl Jaeger wrote:
Nathan,
The only explanation the electrical distributor provided is seen
below. They are really skirting a thorough explanation...
/The distributor engineer does not view the inverters as a negative
load, and states they will exceed the 500A fault current limit the
site is designed for./
Thanks,
Karl
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Nathan Charles
*Sent:* Thursday, March 27, 2014 2:03 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Fault Current
Karl,
Can you give us some more details on their concerns? I've done some
very large single phase ag installs and the only time I've had issues
is when we exceed the 80% of minimum load on the medium voltage feeder.
Best,
-N
On Thu, Mar 27, 2014 at 2:51 PM, Karl Jaeger
<kjae...@lightwavesolar.com <mailto:kjae...@lightwavesolar.com>> wrote:
Dave,
We are about as rural as we can get here.... farm land. Very good
document, nonetheless.
Karl
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] *On Behalf Of
*Dave Click
*Sent:* Thursday, March 27, 2014 1:29 PM
*To:* re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] Fault Current
Karl, you're interconnecting into a spot/area network, right? It's a
real concern; some solutions and background on the issue here:
http://www.nrel.gov/docs/fy09osti/45061.pdf
DKC
On 2014/3/27, 14:05, Karl Jaeger wrote:
Esteemed Wrenches,
We've recently run into an issue with a local distributor citing
network fault current on a split-phase service as a reason to
prevent interconnection of our customer's solar array. They've
given us the options of reducing our system size from 36.5kW-DC to
15kW-DC, or having the customer upgrade to 3-phase at a soft price
of $20-30K. We're looking at 32kW of inverters on a 167kVA
transformer.
Does anyone have experience on circumventing the issue of network
fault current? Any experience with Fault Current Limiters?
Much appreciated,
*Karl Jaeger*
*Design/Build Engineer*
*LightWave Solar Electric LLC*
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Nathan Charles
Engineer
NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions
(717) 283-2021 direct
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