Outboard equipment for PV5 [RE-wrenches]

Tue Jun 12 15:54:16 PDT 2001

Kent / Bill:

I am pretty sure Pulse is still building UL 508A combiners for 600 Vdc
systems.
The old part numbers were PCBHV -XX -YY where XX was the number of
circuits and YY was the rating of the fuse.
FYI: Even if you supplied your own fuses UL required us to put the
ratings on the labels.
     It also impacts the wire terminal sizes and wire bending radius'
during layout.

On the connections loosening over time -
This can be a problem when connections are not properly torque.
If you torque them properly then I think they are not really a problem.
This is why UL is picky about torque on connections.
Typically they spot check work in process and look for calibration
records of your torque wrenches when they do their quarterly
inspections.

No doubt about it - a PCB with soldered on clips is the cheapest way to
go.
BE CAREFUL about the quality of the PCB Fuse clips - I suggest only the
Beryllium (sp?) Copper ones.
The cheapies tend to get hot and lose their spring temper then the
contact pressure drops and then they get hotter and ...

My concern over some of the integrated bus / board solutions I have seen
is exposed terminals that are not touch safe.
IMHO, touch safety should be maintained with or without the fuse in
place.
With the fuse and holder removed you have Voc (from Array #1) on one
side of the clip and Voc (from array #2 to Array #X) on the other side.
Even in a 48 Vdc system this means you have > 100 Vdc sitting on the
clips.
Sometimes the clips get bent when you try to put the fuse in and the
tendency is to reach in there to straighten them out.
This is why we elected not to go with the PCB Clips and instead went
with touch safe holders on the Pulse designs.

I have not seen Kent's design so I don't know how they deal with this
issue.

About diodes - In my experience most people grossly underestimate the
amount of heat generated by Fuses and especially diodes.
If the combiner has diodes then you need really big heat sinks sticking
out of it.
If not, then typically the interior temperatures are going to be above
75 C and this violates the temperature ratings of most terminal blocks.
Also, diodes create a UL nightmare when you go to get them Listed since
UL considers diodes to be "Inherently Unreliable Devices".
Be prepared to spend big bucks on UL temperature tests for each
configuration you plan on using.

If you have any questions or I can be of any further assistance please
do not hesitate to contact me.

Best regards,

John Berdner

SMA-America, Inc.
20830 Red Dog Road
Grass Valley, CA  95945
Tel: 530.273.4895
Fax: 530.274.7271

-----Original Message-----
From: Kent Sheldon [mailto:kentsheldon at tracetec.com]
Sent: Tuesday, June 12, 2001 8:25 AM
To: RE-wrenches at topica.com
Subject: RE: Outboard equipment for PV5 [RE-wrenches]

Thanks for the input Bill, one thing about our combiner boxes. We only
have 10 and 12 circuit models now, each with or without diodes. I don't
sell too many with diodes. They are in NEMA3R wall mount enclosures and
are all UL1741 listed.

The 6, 12, and 22 circuit models were designs we bought from Pulse.
These designs were pretty much off the shelf parts (fuse holders, bus
bar, terminal blocks) manually wired together. This design worked fine
for all the applications I provided them for. Frankly, I prefer the
integrated bus board approach. The fewer mechanincal wire connections
the better. I'm sure that we have all seen mechanicall connections that
loosen over time. They become maintenance items, which seldom get
maintenanced. There is also the cost issue. The bus board approach is
quite a bit less expensive. I'm not sure if the Pulse designs are still
available, given the state of Pulse. John Berdner may be able to expand
on this.

Kent Sheldon
Product Manager, Photovoltaic Systems
Xantrex Technologies, Distributed Industrial & Utility Markets

-----Original Message-----
From: Bill Brooks <billbrooks7 at earthlink.net>
Date: Mon, 11 Jun 2001 21:38:17 -0700
Subject: RE: Outboard equipment for PV5 [RE-wrenches]

> William,
>
> Trace Tech normally sells their equipment to companies that do their
> own
> design engineering or hire engineers to design their systems for
> them. Now
> that they offer smaller inverters, it may seem like they should
> provide more
> design input, but they are not currently setup to do this. Remember,
> they
> service a major part of the variable speed wind turbine industry with
> inverters--huge inverters.
>
> A couple of quick tips for free--then we start charging:
>
> 1. The Trace Tech inverter must have a floating output--either
> connected to
> a delta-delta connection or a delta-open wye configuration. This is
> an
> isolation tranformer. The only way you could use a tranformer on site
> would
> be if it was dedicated to your unit, the transformer was ungrounded,
> and is
> properly rated for the inverter. If you ground the isolation
> transformer,
> the inverter will not work. It is only grounded on the DC side
> (negative
> pole or center-tapped neu. The AC neutral is referenced to ground at
> the
> main sub panel. It is preferable to buy the transformer through Trace
> Tech.
>
> 2. The combiner must be a 600V combiner. This is NOT a TCB-10. Trace
> sells a
> 6,12, and 22-string combiner.
>
> 3. If the AC circuit breaker is within view of the inverter, it could
> be
> used as the AC disconnect. It would need to be at least a three-pole,
> 20-amp
> breaker.
>
> 4. If you support the conduit properly, Rigid Non-Metallic PVC should
> be
> okay. Local codes may govern. Occasionally you run into situation
> where
> Rigid Metallic is necessary. Check with the jurisdiction first.
>
> Bill.
>
>
> > -----Original Message-----
> > From: William Miller [mailto:wrmiller at slonet.org]
> > Sent: Monday, June 11, 2001 6:21 PM
> > To: RE-wrenches at topica.com
> > Subject: Outboard equipment for PV5 [RE-wrenches]
> >
> >
> > Pals:
> >
> > As you all know by now, I am bidding on installation of a Trace
> Technology
> > PV5 and I can't get Trace Tec to return my calls.  Maybe one of you
> can
> > answer some questions:
> >
> > This system will go into a facility with a 440V feeder.  There is
> an
> > existing 208 transformer and sub-panel. Trace lists some equipment
> as
> > optional and a transformer as "required" if the local building
> department
> > requires the panels be grounded or if the line voltage is not 208.
> There
> > is no manual for the PV5.  The manual or the PV10 (AKA the 10208)
> says the
> > transformer is required, period.  The client has a 440 to 208
> transformer
> > already.  Do we still need to purchase one from Trace Tec?  By
> > grounded, do
> > they mean one pole of the DC feed or do they mean the frame of the
> panels?
> >
> > Also, they list a number of optional items and I need to know if
> > I need any
> > or all of them and how they are installed.  For example, they offer
> a 20 A
> > AC circuit breaker.  I have space for a 3 pole breaker in the 208
> panel.
> > Do I need another one?
> >
> > They list a combiner box.   This looks like the same one that has
> flamed
> > out for several wrenches.   This unit will be run at close to 600
> VDC.
> > Will it take this voltage?
> >
> > This is a code question:  This equipment will be installed at a
> public
> > pool.   Can the conduit be installed at about 8 feet above the deck
> (PVC
> > Sked 40)?
> >
> > Thanks for considering these questions.
> >
> > William Miller
> >
> >
> > __________________________________________________________________
> > William Miller
> > SLO Communications: Communications and Power Systems Consulting
> > PO Box 50, Santa Margarita, CA 93453
> > Voice :805-438-5600		Fax: 805-438-4607	VMail: 805-546-
4875
> > email: wrmiller at slonet.org
> > License No. C-10-773985
> > _____________________________________________________________
> > Compatibility:
> > Word processor: WP7
> > Spreadsheet: Quatro Pro 7
> > CAD: Microstation 95, DXF, Visio 4.1T
> > _____________________________________________________________
> > "I stand by all the misstatements that I've made." Dan Quayle
> > __________________________________________________________________
> >
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