[RE-wrenches] AC Coupling Relays

[Drake]

Hello Wrenches,

Do the relays that break the current from the direct grid tie 
inverters, in AC coupled systems, need to be motor rated or can they 
simply be rated for the amperage of the inverter output? How 
inductive is the current between the two inverter systems? Will the 
current tend to jump the contacts on a non motor rated relay, or burn 
them out prematurely?


Thanks,

Drake


Drake Chamberlin
Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV
740-448-7328
http://athens-electric.com/
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Re: [RE-wrenches] Lightning Damage - Need Replacements (Correction)

[Larry Crutcher, Starlight Solar Power Systems]

Hi Dan,

You mentioned that “his grounds didn't work”. Actually, they worked, just in an 
undesirable way. One thing to look at is how or whether the house ground system 
was bonded to the tower ground. If they were not properly bonded, and with poor 
soil condition, the potential difference between the two grounds could create 
very high voltages. The voltage path would be the turbine wiring to find the 
house ground, traveling through any AC connected items to do so.

I would like to hear more about this as it’s a personal subject of study for me.

Larry Crutcher


On Jun 15, 2014, at 4:29 PM, Exeltech  wrote:

Hello Chris,

….The system is off-grid north of Fort Worth, Texas.  The house and equipment 
are sitting on and in the worst caliche I've ever seen.  It's as close to 
concrete as you can get.  There's virtually no topsoil.  Watering grounds won't 
help .. even poured into a hole.  It just sits there.  They had to jackhammer 
to dig the tower hole.

He's got a 110' tower for his Bergey.  He told me they drove numerous grounds 
diagonally into the bottom of the tower hole from the edges, bonded them all 
together, then connected everything to the tower, as well as the other 
equipment using #4 AWG solid.  All of the guy wires are equally bonded.  
Lightning hit the tower directly, but the fact is .. his grounds didn't work.  
Everything electrical in the house was destroyed.  Didn't matter if it was 
turned on or off.

The only things that DID survive are his batteries (as far as he can tell) .. 
and the Bergey itself.  He connected a three-phase diode array directly to the 
Bergey output leads, and it's charging his batteries, just not as well as with 
the controller in place (of course).  The genny runs smoothly in the wind, 
meaning all three phases are intact.  If one or two phases were open, you'd see 
it and hear it in the motion of the blades - much the same effect on the engine 
if you had a plug wire fall off.  If you're a wind person (how can you NOT be 
in Montana?) .. you already knew that.

He may bonded everything to his well casing.  I don't know - but I'll ask.  
This is indeed a good learning opportunity.


I'm going to help him get things operating again .. and will highly recommend 
some of the new lightning protection units Midnite is making.

In the meantime .. charge controllers and inverters first.


Thanks!


Dan


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Re: [RE-wrenches] AC Coupling Relays

[b...@midnitesolar.com]

Since grid-tie inverters sell back with a power factor of 1, the load 
~should~ be entirely resistive and
not inductive or capacitive so a appropriately rated relay contacts 
~should~ be fine.


Except maybe if the inverter is designed to supply VARs like the last 
Solar-Pro magazine talks about.
(haven't actually read that article yet but I assume that's what it is 
about)


Of course, others may have different experiences so I would listen to them.

I prefer to use a somewhat over-rated relay.

boB


On 6/16/2014 7:05 AM, Drake wrote:

Hello Wrenches,

Do the relays that break the current from the direct grid tie 
inverters, in AC coupled systems, need to be motor rated or can they 
simply be rated for the amperage of the inverter output? How inductive 
is the current between the two inverter systems? Will the current tend 
to jump the contacts on a non motor rated relay, or burn them out 
prematurely?


Thanks,

Drake


Drake Chamberlin
/Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV
740-448-7328
/http://athens-electric.com/


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[RE-wrenches] Structural Engineer for Resdiential Project in MA

[James Gustafson]

Dear Wrenches,

I am preparing to install a flush mount roof top solar PV system on a
friends home in North Central Massachusetts.  The local building department
would like a stamped letter from a MA engineer certifying that the roof
structure can support the additional load of the PV system.  I have
contacted two engineers who were recommended by contractor friends in the
area, and neither was willing to take look at the project. Does anyone know
of a MA engineer who could help me with this relatively simple project?

Thank You,

James "Jibril" Gustafson
Tava Solar LLC
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Re: [RE-wrenches] AC Coupling Relays

[Mac Lewis]

Hi Drake,

I think you can put a power diode in parallel to the gt inverter that can
conduct that inductive current if you need to.  However, I think BoB is
correct, there should just be induction of the wiring itself for most
grid-tied inverter.  The relay engineer recommended this diode for a DC
load break application I recently had, so I assume AC would be the same.

Thanks


On Mon, Jun 16, 2014 at 9:11 AM, b...@midnitesolar.com 
wrote:

>
> Since grid-tie inverters sell back with a power factor of 1, the load
> ~should~ be entirely resistive and
> not inductive or capacitive so a appropriately rated relay contacts
> ~should~ be fine.
>
> Except maybe if the inverter is designed to supply VARs like the last
> Solar-Pro magazine talks about.
> (haven't actually read that article yet but I assume that's what it is
> about)
>
> Of course, others may have different experiences so I would listen to them.
>
> I prefer to use a somewhat over-rated relay.
>
> boB
>
>
>
> On 6/16/2014 7:05 AM, Drake wrote:
>
> Hello Wrenches,
>
> Do the relays that break the current from the direct grid tie inverters,
> in AC coupled systems, need to be motor rated or can they simply be rated
> for the amperage of the inverter output? How inductive is the current
> between the two inverter systems? Will the current tend to jump the
> contacts on a non motor rated relay, or burn them out prematurely?
>
> Thanks,
>
> Drake
>
>
> Drake Chamberlin
>
>
>
>
>
> *Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified
> Solar PV 740-448-7328 <740-448-7328> *http://athens-electric.com/
>
>
>
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-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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Re: [RE-wrenches] Lightning Damage - Need Replacements (Correction)

[Exeltech]

Hello Larry,

A number of Wrenches have also contacted me off-list asking me to keep them 
informed.

Clearly interest on this topic is high.  To that point, I'll gladly post 
findings and updates here when information becomes available.

In reference to "his grounds didn't work" .. perhaps I ought to have included 
the words " as intended."

In another life, I owned a business where we designed and installed 
photovoltaic-based mountain-top repeater systems for public service and others. 
 Lightning mitigation is of great interest to me as well.



Dan


On Mon, 6/16/14, Larry Crutcher, Starlight Solar Power Systems 
 wrote:

 Subject: Re: [RE-wrenches] Lightning Damage - Need Replacements (Correction)
 To: "RE-wrenches" 
 Date: Monday, June 16, 2014, 9:44 AM
 
 Hi Dan,

You mentioned that “his grounds didn't work”. Actually, they worked, just in an 
undesirable way. One thing to look at is how or whether the house ground system 
was bonded to the tower ground. If they were not properly bonded, and with poor 
soil condition, the potential difference between the two grounds could create 
very high voltages. The voltage path would be the turbine wiring to find the 
house ground, traveling through any AC connected items to do so.

I would like to hear more about this as it’s a personal subject of study for me.

Larry Crutcher

 
 
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Re: [RE-wrenches] AC Coupling Relays

[Exeltech]

Focus is on the relay contacts.  Any good designer will have already 
incorporated protective diodes for relay DC coils, so nothing needed unless 
specifically stated in the instruction/installation manual.

Do NOT connect any diodes across the relay contacts.

Bob Gudgel is 100% on target with his comments (below).


Dan


On Mon, 6/16/14, Mac Lewis  wrote:

 Subject: Re: [RE-wrenches] AC Coupling Relays
 To: "RE-wrenches" 
 Date: Monday, June 16, 2014, 10:59 AM
 
 Hi Drake,

I think you can put a power diode in parallel to the gt inverter that can 
conduct that inductive current if you need to.  However, I think BoB is 
correct, there should just be induction of the wiring itself for most grid-tied 
inverter.  The relay engineer recommended this diode for a DC load break 
application I recently had, so I assume AC would be the same.

Thanks

 
On Mon, Jun 16, 2014 at 9:11 AM, b...@midnitesolar.com  
wrote:

   
Since grid-tie inverters sell back with a power factor of 1, the load ~should~ 
be entirely resistive and
not inductive or capacitive so a appropriately rated relay contacts ~should~ be 
fine.
 
Except maybe if the inverter is designed to supply VARs like the  last 
Solar-Pro magazine talks about.
(haven't actually read that article yet but I assume that's what it is about)
 
Of course, others may have different experiences so I would listen to them.
 
I prefer to use a somewhat over-rated relay.
 
boB
 
   
 
   
 
On 6/16/2014 7:05 AM, Drake wrote:
 
Hello Wrenches,
 
Do the relays that break the current from the direct grid tie
inverters, in AC coupled systems, need to be motor rated or can
they simply be rated for the amperage of the inverter output? How inductive
is the current between the two inverter systems? Will the current tend to jump
the contacts on a non motor rated relay, or burn them out prematurely?
 
Thanks,
 
   
 
Drake 
 
Drake Chamberlin
Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV 
740-448-7328
http://athens-electric.com/

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[RE-wrenches] inverter/chargers

[Phil Lawes]

Does anyone know of an inverter/charger 48 volt dc input-240 volt ac output
rated 1,500 watts true sine? The only small output inverters I can find are
by Studer or Stecca but so far with European standard outputs.

Thanks

 

Philip N. Lawes

Insoltech Solar

License # 300328

172 wave St.

Laguna Beach, Ca. 92651

Office: (949) 497-6300

   Cell : (949) 510-0687

p...@insoltechsolar.com

www.insoltechsolar.com

 

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Re: [RE-wrenches] inverter/chargers

[Jerry Shafer]

Maybe a outback with a autotransformer
On Jun 16, 2014 12:28 PM, "Phil Lawes"  wrote:

> Does anyone know of an inverter/charger 48 volt dc input-240 volt ac
> output rated 1,500 watts true sine? The only small output inverters I can
> find are by Studer or Stecca but so far with European standard outputs.
>
> Thanks
>
>
>
> Philip N. Lawes
>
> Insoltech Solar
>
> License # 300328
>
> 172 wave St.
>
> Laguna Beach, Ca. 92651
>
> Office: (949) 497-6300
>
>Cell : (949) 510-0687
>
> p...@insoltechsolar.com
>
> www.insoltechsolar.com
>
>
>
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Re: [RE-wrenches] inverter/chargers

[Allan Sindelar]

  
  
Phil,
  I'm not aware of any.
  
  Schneider XW4548 is rated 4500W
  Schneider SW series is not yet offered in 48V
  Magnum 48V is 4000W
  Outback Radian is rated 8000W
  Jerry's suggestion of an FX ith an X-240 may be your best bet. The
  smaller 48V version is rated 25000W.
  Exeltech XP is maximum 1100W - that's your closest option on the
  small side.
  Exeltech MX may be worth investigating; I think that they're
  offered in 1kW modules.
  
  By the way, Positive Energy has a matched pair of 1989-era 48V
  2500W 120/240V mod-square inverter/chargers that worked flawlessly
  for 25 years and still do. Extremely rare, beautifully made, but
  no current market or use for them. We pulled them out during an
  upgrade a few years ago, and they're just too nice to trash. Like
  puppies from the same litter, they are to stay as a matched pair.
  Anybody want 'em real cheap (S&H+)? (reply off list)
  Allan
  
  











  Allan Sindelar
al...@sindelarsolar.com
NABCEP Certified PV
  Installation Professional
  NABCEP Certified Technical Sales Professional
  New Mexico EE98J Journeyman Electrician
  Founder (Retired), Positive Energy,
Inc.
  505 780-2738 cell
  
  
   

  
  On 6/16/2014 1:28 PM, Phil Lawes wrote:


  
  
  
  
Does anyone know of an inverter/charger 48
  volt dc input-240 volt ac output rated 1,500 watts true sine?
  The only small output inverters I can find are by Studer or
  Stecca but so far with European standard outputs.
Thanks
 
Philip N. Lawes
Insoltech Solar
License # 300328
172 wave St.
Laguna Beach, Ca. 92651
Office: (949) 497-6300
   Cell : (949) 510-0687
p...@insoltechsolar.com
www.insoltechsolar.com
 
  
  
  
  
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Re: [RE-wrenches] Flexible stranded Connectors

[Ray Walters]

FYI,  I was going to get the sleeves, but they were special order and 
required a special crimping tool. This project was in Mexico, so I 
pulled the cable out and inspected it after it was torqued.  I found 
excellent compression, and no tearing of the strands.  In my opinion, 
the SMA connectors are good for fine stranded cable, even if they don't 
have the UL listing.
Its one of those: I should have never asked, things.  SMA was obligated 
to say they were not fine strand rated, and I guess I was obligated to 
worry.


R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 4/30/2014 12:01 AM, William Miller wrote:

Ray:

Darn good question, especially since I will be doing the exact same thing, 
*tomorrow*.

I have never been clear on the real problem. Fine stranded cables overheat in 
the wrong lugs?  Is this true for mechanical or compression?

Aside from code compliance, what is the best common sense approach to Sunny 
Islands with fine stranded?  Annual retorquing?  Pin terminals?  Solder tinning 
the strands?

I used to wrap thin copper sheeting around fine stranded just to corral the 
strands. Is this a possible solution?

Thanks Ray for bringing up a question I forgot to consider.

William


Miller Solar


On Apr 29, 2014, at 10:48 PM, Ray Walters  wrote:

Hi All;

In order to avoid any of my work showing up in someone's slideshow of horrors, 
I'm trying to find the correct way to wire 3 Sunny Islands with Cobra X flex 
cable.
While it doesn't actually mention it in the SMA manual, a call to SMA tech 
support confirmed my suspicions: the DC lugs in the inverter are NOT rated for 
flex or fine stranded cable.
Both SMA and CED recommended I try Grainger's for crimp on adapters.  Grainger 
had no clue, and nothing came up in searches there.
 From a trade show, I have an ILSCO lug book, that shows a crimp on pigtail 
adapter.  It does not mention whether its flex rated though on the crimp side 
of the adapter, as the adapter is used primarily to land over sized cables into 
smaller lugs.  (2/0 to #1, for instance)
The best I've found so far, is NSI, which makes sleeves, that are installed 
around the wire, right in the connection:
http://www.nsiindustries.com/products/electrical/connectors/compression-connectors/copper-compression/fsflex-cable-sleeve.aspx
I also found a Schneider white paper recommending sleeves with their lugs:
http://static.schneider-electric.us/docs/Circuit%20Protection/0515DB0301.pdf

So who has used these sleeves, and where do I get them?
The sleeves seem like a decent compromise, whilst the ILSCO pigtail adapters 
are coming in at $40/ ea.. (ouch)

On the internet, I'm seeing several examples of X flex used directly (no 
adapters) with the Sunny Islands, so are folks just blowing off articles 
690.31(F) and 110.14, that specify the connector be rated for flex cable?
And finally, couldn't SMA use a lug that was flex rated?
For example, Marathon makes Class K rated mechanical Lugs: 
http://www.marathonsp.com/NewRatings.html
I'd use THHN, but I really don't feel good about wiring the Heineman breakers 
with that stiff a wire.  I've cracked breaker cases before..that's why the 
X flex is industry standard for off grid DC.

Thanks for your help,

--
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

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Re: [RE-wrenches] Lightning Damage - Need Replacements (Correction)

[PRP]

All  

We have had four Bergey 10K Turbines take a direct strike. Only one strike 
killed all the equipment in the power room. That installer had connected the 
ground wire inside the armored cable that is supplied by Bergey in the wiring 
kit. The cable ground is not supposed to be connected and Bergey does not even 
give the installer a place to connect it. But, he grounded it at the top by the 
3 phase connection and at the bottom in the disconnect box.

The way it has been explained to me is that when the turbine / tower takes a 
strike the electricity travels down the tower and guys, and the OUTSIDE of the 
armored cable dissipating to the ground rods. If the ground wire is connected, 
it allows a direct path to the 3 phase power wires that connect the turbine to 
the equipment in the power room. A short cut and easy path of least resistance 
to the power room.

True or not? I don’t know, but I have great photos of lighting spider webs on 
blade clear coat from  the strikes and paint burnt off PMG’s from strikes and 
no damage to turbine or power equipment. But, the one with the internal power 
cable ground connected killed everything.

I am a believer and do not connect the ground wire and follow Bergey’s 
directions. We also install Midnite SPDs on the turbine 3 phase at the 
disconnect box and at the inverter or VCS in the power room.

My 2 cents from Montana

Logan  


-- Pine Ridge Products LLC
1646 East Highwood Rd
Belt, MT 59412




www.pineridgeproducts.com


On Monday, June 16, 2014 at 8:44 -Jun 16, Larry Crutcher, Starlight Solar Power 
Systems wrote:

> Hi Dan,
>  
> You mentioned that “his grounds didn't work”. Actually, they worked, just in 
> an undesirable way. One thing to look at is how or whether the house ground 
> system was bonded to the tower ground. If they were not properly bonded, and 
> with poor soil condition, the potential difference between the two grounds 
> could create very high voltages. The voltage path would be the turbine wiring 
> to find the house ground, traveling through any AC connected items to do so.
>  
> I would like to hear more about this as it’s a personal subject of study for 
> me.
>  
> Larry Crutcher
>  
>  
> On Jun 15, 2014, at 4:29 PM, Exeltech  (mailto:exelt...@yahoo.com)> wrote:
>  
> Hello Chris,
>  
> ….The system is off-grid north of Fort Worth, Texas. The house and equipment 
> are sitting on and in the worst caliche I've ever seen. It's as close to 
> concrete as you can get. There's virtually no topsoil. Watering grounds won't 
> help .. even poured into a hole. It just sits there. They had to jackhammer 
> to dig the tower hole.
>  
> He's got a 110' tower for his Bergey. He told me they drove numerous grounds 
> diagonally into the bottom of the tower hole from the edges, bonded them all 
> together, then connected everything to the tower, as well as the other 
> equipment using #4 AWG solid. All of the guy wires are equally bonded. 
> Lightning hit the tower directly, but the fact is .. his grounds didn't work. 
> Everything electrical in the house was destroyed. Didn't matter if it was 
> turned on or off.
>  
> The only things that DID survive are his batteries (as far as he can tell) .. 
> and the Bergey itself. He connected a three-phase diode array directly to the 
> Bergey output leads, and it's charging his batteries, just not as well as 
> with the controller in place (of course). The genny runs smoothly in the 
> wind, meaning all three phases are intact. If one or two phases were open, 
> you'd see it and hear it in the motion of the blades - much the same effect 
> on the engine if you had a plug wire fall off. If you're a wind person (how 
> can you NOT be in Montana?) .. you already knew that.
>  
> He may bonded everything to his well casing. I don't know - but I'll ask. 
> This is indeed a good learning opportunity.
>  
>  
> I'm going to help him get things operating again .. and will highly recommend 
> some of the new lightning protection units Midnite is making.
>  
> In the meantime .. charge controllers and inverters first.
>  
>  
> Thanks!
>  
>  
> Dan
>  
>  
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