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On 2/21/09 10:24 AM, Joel Davidson wrote:
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">January
1, 2009 LADWP added another interconnection requirement. See page 8-11
at <a class="moz-txt-link-freetext" href="http://www.ladwp.com/ladwp/cms/ladwp004344.pdf">http://www.ladwp.com/ladwp/cms/ladwp004344.pdf</a><br>
</blockquote>
<br>
I found what I think is the relevant section on p. 36 of the PDF
(called out as p. 1-32 at the top of the page.)<br>
<br>
<br>
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">This
is how a PV commercial project manager described this new requirement:</blockquote>
<br>
I'm curious if this was an LADWP project manager, or someone managing
projects for customers?<br>
<br>
<br>
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">When
a customer, any customer, generates electrical power with the intention
of supplying that power to the electrical grid, the connection to the
grid has to be made below, or on the load-side, of one main switch for
the property.</blockquote>
<br>
They define<br>
<br>
<i>generators using a closed-transition (“make-before-break”) type
transfer switch or a multi- <br>
breaker transfer scheme, or an electrical inverter that can be
configured to operate in a utility <br>
interactive mode constitute a potential back feed source into the
Department’s electric system and are <br>
classified as interactive generators.<br>
</i><br>
<br>
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">
the policy seems to be that the total electricity supplied to any
building or property must be disconnected from the grid by one main
switch.</blockquote>
<br>
The wording appears to be:<br>
<i><br>
All interconnected generating systems shall be connected on the load
side of the customer’s meter switch (main service disconnect device). <br>
</i><br>
I'm wondering about the origins of this requirement. How would they
handle critical power systems (data centers, hospitals, etc. which are
often fed by multiple services entering by different routes?) How
would they handle a premises with multiple service voltages?<br>
<br>
<br>
<br>
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">This
policy is in place for emergency situations, to where fire fighters or
persons on the scene during an emergency would be able to completely
shut down building power with one switch. </blockquote>
<br>
The phrase "pull the meter" comes to mind here...<br>
<br>
<br>
<br>
<blockquote cite="mid:5E2F4F347CE14A2585CD6A749BBC0B06@JOEL" type="cite">This
describes a scenario whereby the grid is disconnected from the building
circuits, but the solar PV is still connected to the building circuits.
Therefore, there is a basic flaw in this requirement; this scenario is
only possible at nighttime- during the daytime, the solar PV system is
energized and may still feed to the building electrical circuits,
unless the main PV disconnect switch is opened.<br>
</blockquote>
<br>
Has this "project manager" ever heard of anti-islanding? This fantasy
scenario almost makes sense for a battery-backed PV system, but then
the presence or absence of sunshine would not matter. What about
emergency backup gensets and UPS or flywheel systems? They are
protected from backfeeding by a transfer switch, so exempted, but UL
1741 does not qualify as such?<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
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