Re: [RE-wrenches] High current dc combiner vibration

[Jerry Shafer via RE-wrenches]

Agree start with data so you know where go

On Sat, Jul 1, 2023, 9:20 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> I'm going to first obtain access to an oscilloscope to characterize and
> screenshot this phenomena, both before and after any mitigation I do.
>
> On Fri, Jun 30, 2023 at 12:46 PM bob--- via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>>
>>
>> We are talking to Kirk offline about this but the main issue here is that
>> the enclosure
>> for the 2000A combiner is made out of steel which is ferrous.  That means
>> that when the
>> 120 Hz ripple current induces into the chassis it can vibrate just like a
>> transformer.
>>
>> Low frequency transformer inverters are have higher ripple than the newer
>> HF transformer units
>> but they have some AC ripple on the battery cables as well.
>>
>> This combiner is evidently been around for about 8 years and we haven't
>> heard any complaints
>> but maybe others have been silent on this.  I am not surprised at all
>> that this happens.
>>
>> Aluminum chassis has the problem that it is a good conductor so when the
>> whole enclosure forms
>> around the cables, the aluminum can act as a shorted turn in a
>> transformer.  It is usually just
>> lossy but should vibrate much less, if at all.
>>
>> There are other issues in switching to aluminum that Robin mentions, here:
>>
>> *"One reason is cost, the other is fasteners, We would need to use press
>> nuts instead of snail shells. *
>> *Snail shells and sheet metal screws don’t do well in aluminum. It is too
>> soft. Aluminum would not *
>>
>>
>> *vibrate from magnetic ripple activity though." *He has some ideas to
>> make aluminum work so we will try those.
>>
>> Now, plastic could work.   Just has to be real thick.Darn physics !
>>
>> Damping can help, like Kirk tried (more can be done here too).  Keeping
>> the cables
>> together best as you can inside the chassis may help as well but moving
>> and routing
>> the cables might also reduce the buzzing some more.
>>
>> That's the latest buzz from here.
>>
>> boB
>> K7IQ
>>
>> On 6/30/2023 8:45 AM, david quattro via RE-wrenches wrote:
>>
>> Ferrite cores can be used for the battery cables to pass through to
>> reduce common mode current
>>
>> On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>> I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner.
>>> They are paired and within .25 " of one another in wire cable tray for 80%
>>> of their respective distance.
>>>
>>> The inverter to combiner sets are 2/0 for each respective inverter. They
>>> are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
>>> Maybe I can send some photos, but can't at present due to computer issues.
>>>
>>> I used cable tray because the CT-rated cable is in free air, no derating
>>> of current required. But merely pairing the leads may be the issue.
>>>
>>> I could rearrange the inverter cables and twist the sets, but doing it
>>> from combiner to battery cabinets is impossible.
>>>
>>> And I'm wondering if this is really necessary if the customer is willing
>>> to live with the issue. What are the ramifications down the road?
>>> Loosening of connections I suppose would be one.
>>>
>>>
>>>
>>> On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
>>> re-wrenches@lists.re-wrenches.org> wrote:
>>>
 Kirk
 As the batteries come up to charge does the vibration subside. Are the
 battery cables spun together "corkscrew like" l have seen this correct DC
 noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
 come in from each side of the battery combiner, how is your install
 configured, how is the cable length same close or very short to very long
 some length is better on FLA's due to resistance under load and charge.
 More information may help with a solution.
 Fun times solar
 NABCEP PV Inspector

 On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
 re-wrenches@lists.re-wrenches.org> wrote:

> All,
>
> I am in the middle of commissioning a 480kwh BP LFP battery bank,
> connected to -10- OB Radian 8kw inverter/chargers.
>
> For the DC combiner I am using midnite 2000 amp combiner boxes,
> modified to mount  class T fuses on the positive bus, for both battery
> inputs and inverter outputs.
>
> For starters, I set the master inverter at a max charge rate of 20 AC
> amps, which equates to a DC charge of about 74 A. All the other inverters
> are automatically set to this charge rate as well.
>
> Turning the chargers on one by one, I started to get quite an audible
> vibration from the combiner box at a combined charge of about 400 to 500 
> A.
>
> So I took the cover off of the combiner, which was vibrating
> noticabllly by feel. Most of the noise was from the cover 

Re: [RE-wrenches] High current dc combiner vibration

[Darryl Thayer via RE-wrenches]

Hi you have the correct people on the job but get at the basics the forces
causing the vibration is magnetic. You have to break the magnetic path.  If
it was electrical a simple cut in the enclosure.  But it is magnetic which
is much harder to stop. If the hum stops with the cover off replace the
cover with polycarbonate plastic

On Sat, Jul 1, 2023, 3:17 PM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> Hi,
> yes I read Robins email, but the class T fuses are in series only with the
> large DC cable breakers (Heineman, Airpax, etc.) in the Outback GSLC. I
> might be missing something, perhaps again.
>
>
> On Sat, Jul 1, 2023 at 3:09 PM Robin  wrote:
>
>> Ryan thinks it may be the classT fuses. We have a vibration issue when
>> classT fuses are connected to CBI breakers.
>>
>> Sent from my iPhone
>>
>> On Jul 1, 2023, at 11:32 AM, b...@midnitesolar.com wrote:
>>
>> 
>> Hi Kirk.  Did you receive the email that Robin sent to you ?
>>
>> You can measure things like, with your scope but you would want to look
>> at the current
>> from the inverter to battery.
>>
>> You could also use your clamp meter and look at DC  and AC.
>> Set it to AC to view the ripple current.
>>
>> I will copy/paste what Robin and Ryan sent to you and our support team
>> below in case it didn't come through.
>>
>> boB
>>
>>
>>
>>
>> On 6/30/2023 7:55 AM, r...@midnitesolar.com wrote:
>>
>> Kirk,
>>
>> Any chance this is the Class T Fuses resonating from the PWM on the DC
>> current? Feel free to give me a call would love to discuss this further
>>
>>
>>
>> 207-416-2006
>>
>>
>>
>> *From:* robin  
>> *Sent:* Friday, June 30, 2023 10:47 AM
>> *To:* kirkh@vermont.solar
>> *Cc:* b...@midnitesolar.com; ryan 
>> ; James Parish 
>> ; t...@midnitesolar.com; Michelle Neville
>>  
>> *Subject:* Vibrations
>>
>>
>>
>> Kirk, Although this is the first I have heard of this, boB says he isn’t
>> surprised. I am copying the tech support group here in hopes we can all
>> learn something.
>>
>>
>>
>> We have been shipping these boxes for about 8 years now and not a peep.
>>
>> boB says the ripple current is 120Hz AC and with that many amps it is not
>> surprising. I will check with our metal suppliers and ask what the cost
>> ramifications are to add stiffening ribs to the cover and possibly other
>> surfaces.
>>
>> I did this years ago on the Trace DR chassis to give it strength, but the
>> idea is the same.
>>
>> I hate to suggest this, but can you epoxy some ¾” x ¾” angle iron or
>> angle aluminum to the inside surface of the cover? Not sure about other
>> surfaces as I tend to fill them up with knockouts and busbars. I suppose
>> you could just span some unused knockouts though. Maybe even add a couple
>> more mounting screws towards the center of the box.
>>
>> We would be very interested in hearing the results.
>>
>> boB says our Rosie may exhibit less noise also as it will have less
>> ripple. We are testing many Rosie inverters paralleled so soon will be able
>> to have this same configuration tested although we don’t have loads large
>> enough to do ten Rosie’s justice.
>>
>> I don’t want to change the enclosure to aluminum for a couple of reasons,
>> but we may have little choice. Aluminum would not vibrate!
>>
>> One reason is cost, the other is fasteners, We would need to use press
>> nuts instead of snail shells. Snail shells and sheet metal screws don’t do
>> well in aluminum. It is too soft. Aluminum would not vibrate from magnetic
>> ripple activity though.
>>
>> OK, I will ask about changing to aluminum. That would probably be less
>> expensive than adding stiffening ribs.
>>
>>
>>
>> Let us know how it goes.
>>
>> Then ask Ryan for a couple of free SPD’s for your trouble.
>>
>>
>>
>> Thanks,
>>
>> Robin Gudgel
>>
>> MidNite Solar
>>
>>
>>
>>
>>
>>
>>
>>
>> On 7/1/2023 9:19 AM, Kirk Herander via RE-wrenches wrote:
>>
>> I'm going to first obtain access to an oscilloscope to characterize and
>> screenshot this phenomena, both before and after any mitigation I do.
>>
>> On Fri, Jun 30, 2023 at 12:46 PM bob--- via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>>
>>>
>>> We are talking to Kirk offline about this but the main issue here is
>>> that the enclosure
>>> for the 2000A combiner is made out of steel which is ferrous.  That
>>> means that when the
>>> 120 Hz ripple current induces into the chassis it can vibrate just like
>>> a transformer.
>>>
>>> Low frequency transformer inverters are have higher ripple than the
>>> newer HF transformer units
>>> but they have some AC ripple on the battery cables as well.
>>>
>>> This combiner is evidently been around for about 8 years and we haven't
>>> heard any complaints
>>> but maybe others have been silent on this.  I am not surprised at all
>>> that this happens.
>>>
>>> Aluminum chassis has the problem that it is a good conductor so when the
>>> whole enclosure forms
>>> around the cables, the aluminum can act as a shorted turn in a
>>> 

Re: [RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

Hi,
yes I read Robins email, but the class T fuses are in series only with the
large DC cable breakers (Heineman, Airpax, etc.) in the Outback GSLC. I
might be missing something, perhaps again.


On Sat, Jul 1, 2023 at 3:09 PM Robin  wrote:

> Ryan thinks it may be the classT fuses. We have a vibration issue when
> classT fuses are connected to CBI breakers.
>
> Sent from my iPhone
>
> On Jul 1, 2023, at 11:32 AM, b...@midnitesolar.com wrote:
>
> 
> Hi Kirk.  Did you receive the email that Robin sent to you ?
>
> You can measure things like, with your scope but you would want to look at
> the current
> from the inverter to battery.
>
> You could also use your clamp meter and look at DC  and AC.
> Set it to AC to view the ripple current.
>
> I will copy/paste what Robin and Ryan sent to you and our support team
> below in case it didn't come through.
>
> boB
>
>
>
>
> On 6/30/2023 7:55 AM, r...@midnitesolar.com wrote:
>
> Kirk,
>
> Any chance this is the Class T Fuses resonating from the PWM on the DC
> current? Feel free to give me a call would love to discuss this further
>
>
>
> 207-416-2006
>
>
>
> *From:* robin  
> *Sent:* Friday, June 30, 2023 10:47 AM
> *To:* kirkh@vermont.solar
> *Cc:* b...@midnitesolar.com; ryan 
> ; James Parish 
> ; t...@midnitesolar.com; Michelle Neville
>  
> *Subject:* Vibrations
>
>
>
> Kirk, Although this is the first I have heard of this, boB says he isn’t
> surprised. I am copying the tech support group here in hopes we can all
> learn something.
>
>
>
> We have been shipping these boxes for about 8 years now and not a peep.
>
> boB says the ripple current is 120Hz AC and with that many amps it is not
> surprising. I will check with our metal suppliers and ask what the cost
> ramifications are to add stiffening ribs to the cover and possibly other
> surfaces.
>
> I did this years ago on the Trace DR chassis to give it strength, but the
> idea is the same.
>
> I hate to suggest this, but can you epoxy some ¾” x ¾” angle iron or angle
> aluminum to the inside surface of the cover? Not sure about other surfaces
> as I tend to fill them up with knockouts and busbars. I suppose you could
> just span some unused knockouts though. Maybe even add a couple more
> mounting screws towards the center of the box.
>
> We would be very interested in hearing the results.
>
> boB says our Rosie may exhibit less noise also as it will have less
> ripple. We are testing many Rosie inverters paralleled so soon will be able
> to have this same configuration tested although we don’t have loads large
> enough to do ten Rosie’s justice.
>
> I don’t want to change the enclosure to aluminum for a couple of reasons,
> but we may have little choice. Aluminum would not vibrate!
>
> One reason is cost, the other is fasteners, We would need to use press
> nuts instead of snail shells. Snail shells and sheet metal screws don’t do
> well in aluminum. It is too soft. Aluminum would not vibrate from magnetic
> ripple activity though.
>
> OK, I will ask about changing to aluminum. That would probably be less
> expensive than adding stiffening ribs.
>
>
>
> Let us know how it goes.
>
> Then ask Ryan for a couple of free SPD’s for your trouble.
>
>
>
> Thanks,
>
> Robin Gudgel
>
> MidNite Solar
>
>
>
>
>
>
>
>
> On 7/1/2023 9:19 AM, Kirk Herander via RE-wrenches wrote:
>
> I'm going to first obtain access to an oscilloscope to characterize and
> screenshot this phenomena, both before and after any mitigation I do.
>
> On Fri, Jun 30, 2023 at 12:46 PM bob--- via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>>
>>
>> We are talking to Kirk offline about this but the main issue here is that
>> the enclosure
>> for the 2000A combiner is made out of steel which is ferrous.  That means
>> that when the
>> 120 Hz ripple current induces into the chassis it can vibrate just like a
>> transformer.
>>
>> Low frequency transformer inverters are have higher ripple than the newer
>> HF transformer units
>> but they have some AC ripple on the battery cables as well.
>>
>> This combiner is evidently been around for about 8 years and we haven't
>> heard any complaints
>> but maybe others have been silent on this.  I am not surprised at all
>> that this happens.
>>
>> Aluminum chassis has the problem that it is a good conductor so when the
>> whole enclosure forms
>> around the cables, the aluminum can act as a shorted turn in a
>> transformer.  It is usually just
>> lossy but should vibrate much less, if at all.
>>
>> There are other issues in switching to aluminum that Robin mentions, here:
>>
>> *"One reason is cost, the other is fasteners, We would need to use press
>> nuts instead of snail shells. *
>> *Snail shells and sheet metal screws don’t do well in aluminum. It is too
>> soft. Aluminum would not *
>>
>>
>> *vibrate from magnetic ripple activity though." *He has some ideas to
>> make aluminum work so we will try those.
>>
>> Now, plastic could work.   Just has to be real thick.Darn physics !
>>

Re: [RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

I'm going to first obtain access to an oscilloscope to characterize and
screenshot this phenomena, both before and after any mitigation I do.

On Fri, Jun 30, 2023 at 12:46 PM bob--- via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

>
>
> We are talking to Kirk offline about this but the main issue here is that
> the enclosure
> for the 2000A combiner is made out of steel which is ferrous.  That means
> that when the
> 120 Hz ripple current induces into the chassis it can vibrate just like a
> transformer.
>
> Low frequency transformer inverters are have higher ripple than the newer
> HF transformer units
> but they have some AC ripple on the battery cables as well.
>
> This combiner is evidently been around for about 8 years and we haven't
> heard any complaints
> but maybe others have been silent on this.  I am not surprised at all that
> this happens.
>
> Aluminum chassis has the problem that it is a good conductor so when the
> whole enclosure forms
> around the cables, the aluminum can act as a shorted turn in a
> transformer.  It is usually just
> lossy but should vibrate much less, if at all.
>
> There are other issues in switching to aluminum that Robin mentions, here:
>
> *"One reason is cost, the other is fasteners, We would need to use press
> nuts instead of snail shells. *
> *Snail shells and sheet metal screws don’t do well in aluminum. It is too
> soft. Aluminum would not *
>
>
> *vibrate from magnetic ripple activity though." *He has some ideas to
> make aluminum work so we will try those.
>
> Now, plastic could work.   Just has to be real thick.Darn physics !
>
> Damping can help, like Kirk tried (more can be done here too).  Keeping
> the cables
> together best as you can inside the chassis may help as well but moving
> and routing
> the cables might also reduce the buzzing some more.
>
> That's the latest buzz from here.
>
> boB
> K7IQ
>
> On 6/30/2023 8:45 AM, david quattro via RE-wrenches wrote:
>
> Ferrite cores can be used for the battery cables to pass through to reduce
> common mode current
>
> On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>> I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner.
>> They are paired and within .25 " of one another in wire cable tray for 80%
>> of their respective distance.
>>
>> The inverter to combiner sets are 2/0 for each respective inverter. They
>> are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
>> Maybe I can send some photos, but can't at present due to computer issues.
>>
>> I used cable tray because the CT-rated cable is in free air, no derating
>> of current required. But merely pairing the leads may be the issue.
>>
>> I could rearrange the inverter cables and twist the sets, but doing it
>> from combiner to battery cabinets is impossible.
>>
>> And I'm wondering if this is really necessary if the customer is willing
>> to live with the issue. What are the ramifications down the road?
>> Loosening of connections I suppose would be one.
>>
>>
>>
>> On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>> Kirk
>>> As the batteries come up to charge does the vibration subside. Are the
>>> battery cables spun together "corkscrew like" l have seen this correct DC
>>> noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
>>> come in from each side of the battery combiner, how is your install
>>> configured, how is the cable length same close or very short to very long
>>> some length is better on FLA's due to resistance under load and charge.
>>> More information may help with a solution.
>>> Fun times solar
>>> NABCEP PV Inspector
>>>
>>> On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
>>> re-wrenches@lists.re-wrenches.org> wrote:
>>>
 All,

 I am in the middle of commissioning a 480kwh BP LFP battery bank,
 connected to -10- OB Radian 8kw inverter/chargers.

 For the DC combiner I am using midnite 2000 amp combiner boxes,
 modified to mount  class T fuses on the positive bus, for both battery
 inputs and inverter outputs.

 For starters, I set the master inverter at a max charge rate of 20 AC
 amps, which equates to a DC charge of about 74 A. All the other inverters
 are automatically set to this charge rate as well.

 Turning the chargers on one by one, I started to get quite an audible
 vibration from the combiner box at a combined charge of about 400 to 500 A.

 So I took the cover off of the combiner, which was vibrating
 noticabllly by feel. Most of the noise was from the cover not fitting
 tight. But the The box itself is also vibrating by feel.

 I took the combined charge up to 640A dc. This level of vibration
 definitely increases with an increased charge rate. And I am surprised
 because after all, we’re not talking AC here 

Re: [RE-wrenches] High current dc combiner vibration

[Jerry Shafer via RE-wrenches]

Wrenches, Kirk
Once you learn what is causing the issue then deciding on what to do is
safer, If you have access to a scope that may show you a DC side
fluctuation, pulsing or plain noise in the system.
Fun times in solar

On Fri, Jun 30, 2023 at 4:00 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner. They
> are paired and within .25 " of one another in wire cable tray for 80% of
> their respective distance.
>
> The inverter to combiner sets are 2/0 for each respective inverter. They
> are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
> Maybe I can send some photos, but can't at present due to computer issues.
>
> I used cable tray because the CT-rated cable is in free air, no derating
> of current required. But merely pairing the leads may be the issue.
>
> I could rearrange the inverter cables and twist the sets, but doing it
> from combiner to battery cabinets is impossible.
>
> And I'm wondering if this is really necessary if the customer is willing
> to live with the issue. What are the ramifications down the road?
> Loosening of connections I suppose would be one.
>
>
>
> On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>> Kirk
>> As the batteries come up to charge does the vibration subside. Are the
>> battery cables spun together "corkscrew like" l have seen this correct DC
>> noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
>> come in from each side of the battery combiner, how is your install
>> configured, how is the cable length same close or very short to very long
>> some length is better on FLA's due to resistance under load and charge.
>> More information may help with a solution.
>> Fun times solar
>> NABCEP PV Inspector
>>
>> On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>> All,
>>>
>>> I am in the middle of commissioning a 480kwh BP LFP battery bank,
>>> connected to -10- OB Radian 8kw inverter/chargers.
>>>
>>> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
>>> to mount  class T fuses on the positive bus, for both battery inputs and
>>> inverter outputs.
>>>
>>> For starters, I set the master inverter at a max charge rate of 20 AC
>>> amps, which equates to a DC charge of about 74 A. All the other inverters
>>> are automatically set to this charge rate as well.
>>>
>>> Turning the chargers on one by one, I started to get quite an audible
>>> vibration from the combiner box at a combined charge of about 400 to 500 A.
>>>
>>> So I took the cover off of the combiner, which was vibrating noticabllly
>>> by feel. Most of the noise was from the cover not fitting tight. But the
>>> The box itself is also vibrating by feel.
>>>
>>> I took the combined charge up to 640A dc. This level of vibration
>>> definitely increases with an increased charge rate. And I am surprised
>>> because after all, we’re not talking AC here we’re talking DC. It almost
>>> reminds me of a large AC transformer in its behavior. The vibration did not
>>> seem to be originating at the inverters, then resonating to the combiner.
>>>
>>> I can dampen the vibration by adding a few things, but I’m surprised
>>> that this is happening. All connections in the combiner are tightened
>>> properly. Ideas?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> *Kirk Herander / **kirkh@vermont.solar *
>>>
>>> *Owner|Principal, VT Solar, LLC*
>>>
>>> *Celebrating our 32st Anniversary 1991-2023!!*
>>>
>>> dba Vermont Solar Engineering
>>>
>>> 802.863.1202
>>> ___
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Re: [RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

Hello, what do people think about the suggestion for chokes to filter this
noise out? How do I go about sizing a choke for something like that? Would
it have to be on each and every positive and negative conductor? And I
assume I’d wanna place those chokes as close as practical to the inverters
because that’s the assumed source of the 120 Hz ripple. And maybe that
approach could also harden the inverters against EMP and other outside
induced noise.

I am using 2 inch SEU connectors, metallic, to pass the cables into and out
of the combiner, I guess that’s not helping things. I was thinking of using
some heat resistant rubber tape/mastic to wrap the cables as they pass
through those connectors at least for dampening.

On Fri, Jun 30, 2023 at 12:46 PM bob--- via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

>
>
> We are talking to Kirk offline about this but the main issue here is that
> the enclosure
> for the 2000A combiner is made out of steel which is ferrous.  That means
> that when the
> 120 Hz ripple current induces into the chassis it can vibrate just like a
> transformer.
>
> Low frequency transformer inverters are have higher ripple than the newer
> HF transformer units
> but they have some AC ripple on the battery cables as well.
>
> This combiner is evidently been around for about 8 years and we haven't
> heard any complaints
> but maybe others have been silent on this.  I am not surprised at all that
> this happens.
>
> Aluminum chassis has the problem that it is a good conductor so when the
> whole enclosure forms
> around the cables, the aluminum can act as a shorted turn in a
> transformer.  It is usually just
> lossy but should vibrate much less, if at all.
>
> There are other issues in switching to aluminum that Robin mentions, here:
>
> *"One reason is cost, the other is fasteners, We would need to use press
> nuts instead of snail shells. *
> *Snail shells and sheet metal screws don’t do well in aluminum. It is too
> soft. Aluminum would not *
>
>
> *vibrate from magnetic ripple activity though." *He has some ideas to
> make aluminum work so we will try those.
>
> Now, plastic could work.   Just has to be real thick.Darn physics !
>
> Damping can help, like Kirk tried (more can be done here too).  Keeping
> the cables
> together best as you can inside the chassis may help as well but moving
> and routing
> the cables might also reduce the buzzing some more.
>
> That's the latest buzz from here.
>
> boB
> K7IQ
>
> On 6/30/2023 8:45 AM, david quattro via RE-wrenches wrote:
>
> Ferrite cores can be used for the battery cables to pass through to reduce
> common mode current
>
> On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>> I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner.
>> They are paired and within .25 " of one another in wire cable tray for 80%
>> of their respective distance.
>>
>> The inverter to combiner sets are 2/0 for each respective inverter. They
>> are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
>> Maybe I can send some photos, but can't at present due to computer issues.
>>
>> I used cable tray because the CT-rated cable is in free air, no derating
>> of current required. But merely pairing the leads may be the issue.
>>
>> I could rearrange the inverter cables and twist the sets, but doing it
>> from combiner to battery cabinets is impossible.
>>
>> And I'm wondering if this is really necessary if the customer is willing
>> to live with the issue. What are the ramifications down the road?
>> Loosening of connections I suppose would be one.
>>
>>
>>
>> On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>> Kirk
>>> As the batteries come up to charge does the vibration subside. Are the
>>> battery cables spun together "corkscrew like" l have seen this correct DC
>>> noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
>>> come in from each side of the battery combiner, how is your install
>>> configured, how is the cable length same close or very short to very long
>>> some length is better on FLA's due to resistance under load and charge.
>>> More information may help with a solution.
>>> Fun times solar
>>> NABCEP PV Inspector
>>>
>>> On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
>>> re-wrenches@lists.re-wrenches.org> wrote:
>>>
 All,

 I am in the middle of commissioning a 480kwh BP LFP battery bank,
 connected to -10- OB Radian 8kw inverter/chargers.

 For the DC combiner I am using midnite 2000 amp combiner boxes,
 modified to mount  class T fuses on the positive bus, for both battery
 inputs and inverter outputs.

 For starters, I set the master inverter at a max charge rate of 20 AC
 amps, which equates to a DC charge of about 74 A. All the other inverters
 are automatically set to this charge 

Re: [RE-wrenches] High current dc combiner vibration

[Darryl Thayer via RE-wrenches]

Are we all thinking single phase? Another idea would be to use plastic
enclosures in at least some way to break the magnetic path.  This is a lot
of current, and it will cause magnetic heating where the magnetic loop is
complete.

On Thu, Jun 29, 2023 at 10:19 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> All,
>
> I am in the middle of commissioning a 480kwh BP LFP battery bank,
> connected to -10- OB Radian 8kw inverter/chargers.
>
> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
> to mount  class T fuses on the positive bus, for both battery inputs and
> inverter outputs.
>
> For starters, I set the master inverter at a max charge rate of 20 AC
> amps, which equates to a DC charge of about 74 A. All the other inverters
> are automatically set to this charge rate as well.
>
> Turning the chargers on one by one, I started to get quite an audible
> vibration from the combiner box at a combined charge of about 400 to 500 A.
>
> So I took the cover off of the combiner, which was vibrating noticabllly
> by feel. Most of the noise was from the cover not fitting tight. But the
> The box itself is also vibrating by feel.
>
> I took the combined charge up to 640A dc. This level of vibration
> definitely increases with an increased charge rate. And I am surprised
> because after all, we’re not talking AC here we’re talking DC. It almost
> reminds me of a large AC transformer in its behavior. The vibration did not
> seem to be originating at the inverters, then resonating to the combiner.
>
> I can dampen the vibration by adding a few things, but I’m surprised that
> this is happening. All connections in the combiner are tightened properly.
> Ideas?
>
>
>
>
>
>
>
>
>
>
> --
>
> *Kirk Herander / **kirkh@vermont.solar *
>
> *Owner|Principal, VT Solar, LLC*
>
> *Celebrating our 32st Anniversary 1991-2023!!*
>
> dba Vermont Solar Engineering
>
> 802.863.1202
> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
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>
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Re: [RE-wrenches] High current dc combiner vibration

[bob--- via RE-wrenches]

We are talking to Kirk offline about this but the main issue here is 
that the enclosure
for the 2000A combiner is made out of steel which is ferrous.  That 
means that when the
120 Hz ripple current induces into the chassis it can vibrate just like 
a transformer.


Low frequency transformer inverters are have higher ripple than the 
newer HF transformer units

but they have some AC ripple on the battery cables as well.

This combiner is evidently been around for about 8 years and we haven't 
heard any complaints
but maybe others have been silent on this.  I am not surprised at all 
that this happens.


Aluminum chassis has the problem that it is a good conductor so when the 
whole enclosure forms
around the cables, the aluminum can act as a shorted turn in a 
transformer.  It is usually just

lossy but should vibrate much less, if at all.

There are other issues in switching to aluminum that Robin mentions, here:

/"One reason is cost, the other is fasteners, We would need to use press 
nuts instead of snail shells. //
//Snail shells and sheet metal screws don’t do well in aluminum. It is 
too soft. Aluminum would not //

//vibrate from magnetic ripple activity though."

/He has some ideas to make aluminum work so we will try those./
/
Now, plastic could work.   Just has to be real thick.    Darn physics !

Damping can help, like Kirk tried (more can be done here too). Keeping 
the cables
together best as you can inside the chassis may help as well but moving 
and routing

the cables might also reduce the buzzing some more.

That's the latest buzz from here.

boB
    K7IQ

On 6/30/2023 8:45 AM, david quattro via RE-wrenches wrote:
Ferrite cores can be used for the battery cables to pass through to 
reduce common mode current


On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches 
 wrote:


I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the
combiner. They are paired and within .25 " of one another in wire
cable tray for 80% of their respective distance.

The inverter to combiner sets are 2/0 for each respective
inverter. They are paired (not twisted) in cable tray, anywhere
from 10 -20' in length. Maybe I can send some photos, but can't at
present due to computer issues.

I used cable tray because the CT-rated cable is in free air, no
derating of current required. But merely pairing the leads may be
the issue.

I could rearrange the inverter cables and twist the sets, but
doing it from combiner to battery cabinets is impossible.

And I'm wondering if this is really necessary if the customer is
willing to live with the issue. What are the ramifications down
the road? Loosening of connections I suppose would be one.



On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches
 wrote:

Kirk
As the batteries come up to charge does the vibration subside.
Are the battery cables spun together "corkscrew like" l have
seen this correct DC noise. I have an 8 on 8 just like your 10
and l have no noise at all, mine come in from each side of the
battery combiner, how is your install configured, how is the
cable length same close or very short to very long some length
is better on FLA's due to resistance under load and charge.
More information may help with a solution.
Fun times solar
NABCEP PV Inspector

On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches
 wrote:

All,

I am in the middle of commissioning a 480kwh BP LFP
battery bank, connected to -10- OB Radian 8kw
inverter/chargers.

For the DC combiner I am using midnite 2000 amp combiner
boxes, modified to mount  class T fuses on the positive
bus, for both battery inputs and inverter outputs.

For starters, I set the master inverter at a max charge
rate of 20 AC amps, which equates to a DC charge of about
74 A. All the other inverters are automatically set to
this charge rate as well.

Turning the chargers on one by one, I started to get quite
an audible vibration from the combiner box at a combined
charge of about 400 to 500 A.

So I took the cover off of the combiner, which was
vibrating noticabllly by feel. Most of the noise was from
the cover not fitting tight. But the The box itself is
also vibrating by feel.

I took the combined charge up to 640A dc. This level of
vibration definitely increases with an increased charge
rate. And I am surprised because after all, we’re not
talking AC here we’re talking DC. It almost reminds me of
a large AC transformer in its behavior. The vibration did
not seem to be originating at the inverters, then
resonating to the 

Re: [RE-wrenches] High current dc combiner vibration

[david quattro via RE-wrenches]

Ferrite cores can be used for the battery cables to pass through to reduce
common mode current

On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner. They
> are paired and within .25 " of one another in wire cable tray for 80% of
> their respective distance.
>
> The inverter to combiner sets are 2/0 for each respective inverter. They
> are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
> Maybe I can send some photos, but can't at present due to computer issues.
>
> I used cable tray because the CT-rated cable is in free air, no derating
> of current required. But merely pairing the leads may be the issue.
>
> I could rearrange the inverter cables and twist the sets, but doing it
> from combiner to battery cabinets is impossible.
>
> And I'm wondering if this is really necessary if the customer is willing
> to live with the issue. What are the ramifications down the road?
> Loosening of connections I suppose would be one.
>
>
>
> On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>> Kirk
>> As the batteries come up to charge does the vibration subside. Are the
>> battery cables spun together "corkscrew like" l have seen this correct DC
>> noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
>> come in from each side of the battery combiner, how is your install
>> configured, how is the cable length same close or very short to very long
>> some length is better on FLA's due to resistance under load and charge.
>> More information may help with a solution.
>> Fun times solar
>> NABCEP PV Inspector
>>
>> On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
>> re-wrenches@lists.re-wrenches.org> wrote:
>>
>>> All,
>>>
>>> I am in the middle of commissioning a 480kwh BP LFP battery bank,
>>> connected to -10- OB Radian 8kw inverter/chargers.
>>>
>>> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
>>> to mount  class T fuses on the positive bus, for both battery inputs and
>>> inverter outputs.
>>>
>>> For starters, I set the master inverter at a max charge rate of 20 AC
>>> amps, which equates to a DC charge of about 74 A. All the other inverters
>>> are automatically set to this charge rate as well.
>>>
>>> Turning the chargers on one by one, I started to get quite an audible
>>> vibration from the combiner box at a combined charge of about 400 to 500 A.
>>>
>>> So I took the cover off of the combiner, which was vibrating noticabllly
>>> by feel. Most of the noise was from the cover not fitting tight. But the
>>> The box itself is also vibrating by feel.
>>>
>>> I took the combined charge up to 640A dc. This level of vibration
>>> definitely increases with an increased charge rate. And I am surprised
>>> because after all, we’re not talking AC here we’re talking DC. It almost
>>> reminds me of a large AC transformer in its behavior. The vibration did not
>>> seem to be originating at the inverters, then resonating to the combiner.
>>>
>>> I can dampen the vibration by adding a few things, but I’m surprised
>>> that this is happening. All connections in the combiner are tightened
>>> properly. Ideas?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> *Kirk Herander / **kirkh@vermont.solar *
>>>
>>> *Owner|Principal, VT Solar, LLC*
>>>
>>> *Celebrating our 32st Anniversary 1991-2023!!*
>>>
>>> dba Vermont Solar Engineering
>>>
>>> 802.863.1202
>>> ___
>>> List sponsored by Redwood Alliance
>>>
>>> Pay optional member dues here: http://re-wrenches.org
>>>
>>> List Address: RE-wrenches@lists.re-wrenches.org
>>>
>>> Change listserver email address & settings:
>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>
>>> There are two list archives for searching. When one doesn't work, try
>>> the other:
>>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>>
>>> List rules & etiquette:
>>> http://www.re-wrenches.org/etiquette.htm
>>>
>>> Check out or update participant bios:
>>> http://www.members.re-wrenches.org
>>>
>>> ___
>> List sponsored by Redwood Alliance
>>
>> Pay optional member dues here: http://re-wrenches.org
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> There are two list archives for searching. When one doesn't work, try the
>> other:
>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>
>> List rules & etiquette:
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>>
>> Check out or update participant bios:
>> 

Re: [RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner. They
are paired and within .25 " of one another in wire cable tray for 80% of
their respective distance.

The inverter to combiner sets are 2/0 for each respective inverter. They
are paired (not twisted) in cable tray, anywhere from 10 -20' in length.
Maybe I can send some photos, but can't at present due to computer issues.

I used cable tray because the CT-rated cable is in free air, no derating of
current required. But merely pairing the leads may be the issue.

I could rearrange the inverter cables and twist the sets, but doing it from
combiner to battery cabinets is impossible.

And I'm wondering if this is really necessary if the customer is willing to
live with the issue. What are the ramifications down the road? Loosening of
connections I suppose would be one.



On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> Kirk
> As the batteries come up to charge does the vibration subside. Are the
> battery cables spun together "corkscrew like" l have seen this correct DC
> noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
> come in from each side of the battery combiner, how is your install
> configured, how is the cable length same close or very short to very long
> some length is better on FLA's due to resistance under load and charge.
> More information may help with a solution.
> Fun times solar
> NABCEP PV Inspector
>
> On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>> All,
>>
>> I am in the middle of commissioning a 480kwh BP LFP battery bank,
>> connected to -10- OB Radian 8kw inverter/chargers.
>>
>> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
>> to mount  class T fuses on the positive bus, for both battery inputs and
>> inverter outputs.
>>
>> For starters, I set the master inverter at a max charge rate of 20 AC
>> amps, which equates to a DC charge of about 74 A. All the other inverters
>> are automatically set to this charge rate as well.
>>
>> Turning the chargers on one by one, I started to get quite an audible
>> vibration from the combiner box at a combined charge of about 400 to 500 A.
>>
>> So I took the cover off of the combiner, which was vibrating noticabllly
>> by feel. Most of the noise was from the cover not fitting tight. But the
>> The box itself is also vibrating by feel.
>>
>> I took the combined charge up to 640A dc. This level of vibration
>> definitely increases with an increased charge rate. And I am surprised
>> because after all, we’re not talking AC here we’re talking DC. It almost
>> reminds me of a large AC transformer in its behavior. The vibration did not
>> seem to be originating at the inverters, then resonating to the combiner.
>>
>> I can dampen the vibration by adding a few things, but I’m surprised that
>> this is happening. All connections in the combiner are tightened properly.
>> Ideas?
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> --
>>
>> *Kirk Herander / **kirkh@vermont.solar *
>>
>> *Owner|Principal, VT Solar, LLC*
>>
>> *Celebrating our 32st Anniversary 1991-2023!!*
>>
>> dba Vermont Solar Engineering
>>
>> 802.863.1202
>> ___
>> List sponsored by Redwood Alliance
>>
>> Pay optional member dues here: http://re-wrenches.org
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> There are two list archives for searching. When one doesn't work, try the
>> other:
>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>
>> List rules & etiquette:
>> http://www.re-wrenches.org/etiquette.htm
>>
>> Check out or update participant bios:
>> http://www.members.re-wrenches.org
>>
>> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
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>

-- 

*Kirk Herander / **kirkh@vermont.solar *

*Owner|Principal, VT Solar, LLC*

*Celebrating our 32st Anniversary 1991-2023!!*

dba Vermont Solar Engineering

802.863.1202
___
List sponsored by Redwood Alliance

Pay optional member dues here: http://re-wrenches.org

List Address: 

Re: [RE-wrenches] High current dc combiner vibration

[Jerry Shafer via RE-wrenches]

Kirk
As the batteries come up to charge does the vibration subside. Are the
battery cables spun together "corkscrew like" l have seen this correct DC
noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine
come in from each side of the battery combiner, how is your install
configured, how is the cable length same close or very short to very long
some length is better on FLA's due to resistance under load and charge.
More information may help with a solution.
Fun times solar
NABCEP PV Inspector

On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> All,
>
> I am in the middle of commissioning a 480kwh BP LFP battery bank,
> connected to -10- OB Radian 8kw inverter/chargers.
>
> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
> to mount  class T fuses on the positive bus, for both battery inputs and
> inverter outputs.
>
> For starters, I set the master inverter at a max charge rate of 20 AC
> amps, which equates to a DC charge of about 74 A. All the other inverters
> are automatically set to this charge rate as well.
>
> Turning the chargers on one by one, I started to get quite an audible
> vibration from the combiner box at a combined charge of about 400 to 500 A.
>
> So I took the cover off of the combiner, which was vibrating noticabllly
> by feel. Most of the noise was from the cover not fitting tight. But the
> The box itself is also vibrating by feel.
>
> I took the combined charge up to 640A dc. This level of vibration
> definitely increases with an increased charge rate. And I am surprised
> because after all, we’re not talking AC here we’re talking DC. It almost
> reminds me of a large AC transformer in its behavior. The vibration did not
> seem to be originating at the inverters, then resonating to the combiner.
>
> I can dampen the vibration by adding a few things, but I’m surprised that
> this is happening. All connections in the combiner are tightened properly.
> Ideas?
>
>
>
>
>
>
>
>
>
>
> --
>
> *Kirk Herander / **kirkh@vermont.solar *
>
> *Owner|Principal, VT Solar, LLC*
>
> *Celebrating our 32st Anniversary 1991-2023!!*
>
> dba Vermont Solar Engineering
>
> 802.863.1202
> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> http://www.members.re-wrenches.org
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>
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Re: [RE-wrenches] High current dc combiner vibration

[Nick A Lucchese via RE-wrenches]

Good morning all. Seems we’ve all been aware of best practices for keeping DC 
cables bound together and twisted when possible. Does anyone know why Simpliphi 
recommends the exact opposite on page 18 of their installation manual? I recall 
observing this awhile ago and thought it was just something that they would 
remedy in their next manual revision cycle but appears to still be noted. Has 
their own validated testing for Simpliphi specific installs concluded to be 
contrary to others?

Off to work, Nick


> On Jun 29, 2023, at 10:09 AM, Kirk Herander via RE-wrenches 
>  wrote:
> 
> I have not twisted them. It is a lot of Cable as you might imagine and they 
> aren’t paired close together individual inverter to combiner or combiner to 
> battery cabinets, not 100% of the cable lengths anyway, maybe on average 80% 
> 
> On Thu, Jun 29, 2023 at 12:25 PM Starlight  > wrote:
> You may already know but… Are your DC cables bonded together and twisted 
> where possible to reduce magnetic fields? Higher the current and greater the 
> loop area, the stronger the fields are. More parallel loops, the greater the 
> combined flux = loud Hums.  
> 
> Larry Crutcher
> Starlight Solar Power Systems
> 
> 
> 
> 
> On Jun 29, 2023, at 8:19 AM, Kirk Herander via RE-wrenches 
>  > wrote:
> 
> All, 
> 
> I am in the middle of commissioning a 480kwh BP LFP battery bank, connected 
> to -10- OB Radian 8kw inverter/chargers.
> 
> For the DC combiner I am using midnite 2000 amp combiner boxes, modified to 
> mount  class T fuses on the positive bus, for both battery inputs and 
> inverter outputs.
> 
> For starters, I set the master inverter at a max charge rate of 20 AC amps, 
> which equates to a DC charge of about 74 A. All the other inverters are 
> automatically set to this charge rate as well.
> 
> Turning the chargers on one by one, I started to get quite an audible 
> vibration from the combiner box at a combined charge of about 400 to 500 A. 
> 
> So I took the cover off of the combiner, which was vibrating noticabllly by 
> feel. Most of the noise was from the cover not fitting tight. But the The box 
> itself is also vibrating by feel.
> 
> I took the combined charge up to 640A dc. This level of vibration definitely 
> increases with an increased charge rate. And I am surprised because after 
> all, we’re not talking AC here we’re talking DC. It almost reminds me of a 
> large AC transformer in its behavior. The vibration did not seem to be 
> originating at the inverters, then resonating to the combiner.
> 
> I can dampen the vibration by adding a few things, but I’m surprised that 
> this is happening. All connections in the combiner are tightened properly. 
> Ideas?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> -- 
> Kirk Herander /  <>kirkh@vermont.solar 
> Owner|Principal, VT Solar, LLC
> Celebrating our 32st Anniversary 1991-2023!!
> dba Vermont Solar Engineering
> 802.863.1202
> ___
> List sponsored by Redwood Alliance
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> -- 
> Kirk Herander /  <>kirkh@vermont.solar 
> Owner|Principal, VT Solar, LLC
> Celebrating our 32st Anniversary 1991-2023!!
> dba Vermont Solar Engineering
> 802.863.1202
> ___
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Re: [RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

I have not twisted them. It is a lot of Cable as you might imagine and they
aren’t paired close together individual inverter to combiner or combiner to
battery cabinets, not 100% of the cable lengths anyway, maybe on average
80%

On Thu, Jun 29, 2023 at 12:25 PM Starlight  wrote:

> You may already know but… Are your DC cables bonded together and twisted
> where possible to reduce magnetic fields? Higher the current and greater
> the loop area, the stronger the fields are. More parallel loops, the
> greater the combined flux = loud Hums.
>
> Larry Crutcher
> Starlight Solar Power Systems
>
>
>
>
> On Jun 29, 2023, at 8:19 AM, Kirk Herander via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
> All,
>
> I am in the middle of commissioning a 480kwh BP LFP battery bank,
> connected to -10- OB Radian 8kw inverter/chargers.
>
> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
> to mount  class T fuses on the positive bus, for both battery inputs and
> inverter outputs.
>
> For starters, I set the master inverter at a max charge rate of 20 AC
> amps, which equates to a DC charge of about 74 A. All the other inverters
> are automatically set to this charge rate as well.
>
> Turning the chargers on one by one, I started to get quite an audible
> vibration from the combiner box at a combined charge of about 400 to 500 A.
>
> So I took the cover off of the combiner, which was vibrating noticabllly
> by feel. Most of the noise was from the cover not fitting tight. But the
> The box itself is also vibrating by feel.
>
> I took the combined charge up to 640A dc. This level of vibration
> definitely increases with an increased charge rate. And I am surprised
> because after all, we’re not talking AC here we’re talking DC. It almost
> reminds me of a large AC transformer in its behavior. The vibration did not
> seem to be originating at the inverters, then resonating to the combiner.
>
> I can dampen the vibration by adding a few things, but I’m surprised that
> this is happening. All connections in the combiner are tightened properly.
> Ideas?
>
>
>
>
>
>
>
>
>
>
> --
> *Kirk Herander / **kirkh@vermont.solar *
> *Owner|Principal, VT Solar, LLC*
> *Celebrating our 32st Anniversary 1991-2023!!*
> dba Vermont Solar Engineering
> 802.863.1202
> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
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>
> --

*Kirk Herander / **kirkh@vermont.solar *

*Owner|Principal, VT Solar, LLC*

*Celebrating our 32st Anniversary 1991-2023!!*

dba Vermont Solar Engineering

802.863.1202
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Re: [RE-wrenches] High current dc combiner vibration

[bob--- via RE-wrenches]

The battery cables being close together, twisted too if possible, help 
reduce cable inductance
which can cause voltage drop across those cables at higher currents with 
120 Hz ripple.

Mainly with low frequency transformer inverter/chargers.

It's better to have them closer together than far apart, especially for 
longer battery cables.


boB

On 6/29/2023 9:24 AM, Starlight via RE-wrenches wrote:
You may already know but… Are your DC cables bonded together and 
twisted where possible to reduce magnetic fields? Higher the current 
and greater the loop area, the stronger the fields are. More parallel 
loops, the greater the combined flux = loud Hums.


Larry Crutcher
Starlight Solar Power Systems




On Jun 29, 2023, at 8:19 AM, Kirk Herander via RE-wrenches 
 wrote:


All,

I am in the middle of commissioning a 480kwh BP LFP battery bank, 
connected to -10- OB Radian 8kw inverter/chargers.


For the DC combiner I am using midnite 2000 amp combiner boxes, 
modified to mount  class T fuses on the positive bus, for both battery 
inputs and inverter outputs.


For starters, I set the master inverter at a max charge rate of 20 AC 
amps, which equates to a DC charge of about 74 A. All the other 
inverters are automatically set to this charge rate as well.


Turning the chargers on one by one, I started to get quite an audible 
vibration from the combiner box at a combined charge of about 400 to 
500 A.


So I took the cover off of the combiner, which was vibrating 
noticabllly by feel. Most of the noise was from the cover not fitting 
tight. But the The box itself is also vibrating by feel.


I took the combined charge up to 640A dc. This level of vibration 
definitely increases with an increased charge rate. And I am surprised 
because after all, we’re not talking AC here we’re talking DC. It 
almost reminds me of a large AC transformer in its behavior. The 
vibration did not seem to be originating at the inverters, then 
resonating to the combiner.


I can dampen the vibration by adding a few things, but I’m surprised 
that this is happening. All connections in the combiner are tightened 
properly. Ideas?











--
*Kirk Herander / **kirkh@vermont.solar*
*Owner|Principal, VT Solar, LLC*
*/Celebrating our 32^st  Anniversary 1991-2023!!/*
dba Vermont Solar Engineering
802.863.1202
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Re: [RE-wrenches] High current dc combiner vibration

[Darryl Thayer via RE-wrenches]

Hi all, just a few comments, The inverter charger has a ripple on the DC.
All have this; Outback is no exception.
However, all wires should be run together, positive and negative
same conduit and same hole, as the AC ripple magnetic effects cancel
from both wires.  Also, the circuit breaker has an internal loop to assist
in the trip, you may want to form a loop on the non-breaker conductor.
Years ago, I was faced with the ripple on the DC problem using a Xantrex
inverter (I think) I added a 150-volt electrolytic capacitor across the
battery lines, CAUTION: this may destroy the Radians So check with
Outback!!!

On Thu, Jun 29, 2023 at 10:19 AM Kirk Herander via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> All,
>
> I am in the middle of commissioning a 480kwh BP LFP battery bank,
> connected to -10- OB Radian 8kw inverter/chargers.
>
> For the DC combiner I am using midnite 2000 amp combiner boxes, modified
> to mount  class T fuses on the positive bus, for both battery inputs and
> inverter outputs.
>
> For starters, I set the master inverter at a max charge rate of 20 AC
> amps, which equates to a DC charge of about 74 A. All the other inverters
> are automatically set to this charge rate as well.
>
> Turning the chargers on one by one, I started to get quite an audible
> vibration from the combiner box at a combined charge of about 400 to 500 A.
>
> So I took the cover off of the combiner, which was vibrating noticabllly
> by feel. Most of the noise was from the cover not fitting tight. But the
> The box itself is also vibrating by feel.
>
> I took the combined charge up to 640A dc. This level of vibration
> definitely increases with an increased charge rate. And I am surprised
> because after all, we’re not talking AC here we’re talking DC. It almost
> reminds me of a large AC transformer in its behavior. The vibration did not
> seem to be originating at the inverters, then resonating to the combiner.
>
> I can dampen the vibration by adding a few things, but I’m surprised that
> this is happening. All connections in the combiner are tightened properly.
> Ideas?
>
>
>
>
>
>
>
>
>
>
> --
>
> *Kirk Herander / **kirkh@vermont.solar *
>
> *Owner|Principal, VT Solar, LLC*
>
> *Celebrating our 32st Anniversary 1991-2023!!*
>
> dba Vermont Solar Engineering
>
> 802.863.1202
> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
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Re: [RE-wrenches] High current dc combiner vibration

[Starlight via RE-wrenches]

You may already know but… Are your DC cables bonded together and twisted where 
possible to reduce magnetic fields? Higher the current and greater the loop 
area, the stronger the fields are. More parallel loops, the greater the 
combined flux = loud Hums.  

Larry Crutcher
Starlight Solar Power Systems




On Jun 29, 2023, at 8:19 AM, Kirk Herander via RE-wrenches 
 wrote:

All, 

I am in the middle of commissioning a 480kwh BP LFP battery bank, connected to 
-10- OB Radian 8kw inverter/chargers.

For the DC combiner I am using midnite 2000 amp combiner boxes, modified to 
mount  class T fuses on the positive bus, for both battery inputs and inverter 
outputs.

For starters, I set the master inverter at a max charge rate of 20 AC amps, 
which equates to a DC charge of about 74 A. All the other inverters are 
automatically set to this charge rate as well.

Turning the chargers on one by one, I started to get quite an audible vibration 
from the combiner box at a combined charge of about 400 to 500 A. 

So I took the cover off of the combiner, which was vibrating noticabllly by 
feel. Most of the noise was from the cover not fitting tight. But the The box 
itself is also vibrating by feel.

I took the combined charge up to 640A dc. This level of vibration definitely 
increases with an increased charge rate. And I am surprised because after all, 
we’re not talking AC here we’re talking DC. It almost reminds me of a large AC 
transformer in its behavior. The vibration did not seem to be originating at 
the inverters, then resonating to the combiner.

I can dampen the vibration by adding a few things, but I’m surprised that this 
is happening. All connections in the combiner are tightened properly. Ideas?










-- 
Kirk Herander /  <>kirkh@vermont.solar 
Owner|Principal, VT Solar, LLC
Celebrating our 32st Anniversary 1991-2023!!
dba Vermont Solar Engineering
802.863.1202
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[RE-wrenches] High current dc combiner vibration

[Kirk Herander via RE-wrenches]

All,

I am in the middle of commissioning a 480kwh BP LFP battery bank, connected
to -10- OB Radian 8kw inverter/chargers.

For the DC combiner I am using midnite 2000 amp combiner boxes, modified to
mount  class T fuses on the positive bus, for both battery inputs and
inverter outputs.

For starters, I set the master inverter at a max charge rate of 20 AC amps,
which equates to a DC charge of about 74 A. All the other inverters are
automatically set to this charge rate as well.

Turning the chargers on one by one, I started to get quite an audible
vibration from the combiner box at a combined charge of about 400 to 500 A.

So I took the cover off of the combiner, which was vibrating noticabllly by
feel. Most of the noise was from the cover not fitting tight. But the The
box itself is also vibrating by feel.

I took the combined charge up to 640A dc. This level of vibration
definitely increases with an increased charge rate. And I am surprised
because after all, we’re not talking AC here we’re talking DC. It almost
reminds me of a large AC transformer in its behavior. The vibration did not
seem to be originating at the inverters, then resonating to the combiner.

I can dampen the vibration by adding a few things, but I’m surprised that
this is happening. All connections in the combiner are tightened properly.
Ideas?










-- 

*Kirk Herander / **kirkh@vermont.solar *

*Owner|Principal, VT Solar, LLC*

*Celebrating our 32st Anniversary 1991-2023!!*

dba Vermont Solar Engineering

802.863.1202
___
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