Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Jason Szumlanski]

That is a potential solution, but if SMA is recommending load shedding
contactors, shouldn't they supply a device or kit to implement this? Or at
least specify products or at a bare minimum provide better documentation on
how and why to implement it.

I still don't understand why it's recommended with Battery Protection Mode
providing essentially the same function, unless you are trying to shed a
subset of loads.

Jason


On Fri, Jan 22, 2021, 3:24 PM  wrote:

> Use series resistors around the coil.
> ---
>
>
>
> On 2021-01-21 13:59, Jason Szumlanski wrote:
>
> I just learned from the manufacturer that the mercury displacement relay's
> coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed
> 52.8 pretty significantly. Does the Sunny Island regulate the output
> voltage on this relay to 48V or is the actual battery voltage passed
> through on this terminal?
>
> The more I read about this load shedding strategy, the more it seems
> overly complicated. It's also another thing to fail. If the N.O. contactor
> coil fails, the loads to the house are going to lose power. That's not good
> for a remote installation. I guess you have to weigh battery protection
> with how critical the loads are.
>
> I'm wondering why the internal Battery Preservation Mode isn't sufficient
> enough. What's the purpose of load shedding if the BPM does effectively the
> same thing. I can see perhaps shedding some parts of the load and that is a
> nice feature, but to protect the batteries, why isn't BPM enough?
>
> Jason
>
>
>
> On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:
>
> Hi Jason,
>
> I have done this with mercury displacement relays:
>
> https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
> 
>
> They do have a 100A 2P 48V coil relay.  They seem to work perfectly.
>
> Good luck
>
> On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
> Does anyone know where I can get a load shedding contactor described in
> SMA documentation for use with a multi-function relay in a Sunny Island?
>
> Thanks,
>
> Jason Szumlanski
> ___
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>
> --
>
>
>
> Mac Lewis
>
> "Yo solo sé que no sé nada." -Sócrates
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Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[drake . chamberlin]

Use series resistors around the coil. 


---

On 2021-01-21 13:59, Jason Szumlanski wrote:

I just learned from the manufacturer that the mercury displacement relay's coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed 52.8 pretty significantly. Does the Sunny Island regulate the output voltage on this relay to 48V or is the actual battery voltage passed through on this terminal? 

The more I read about this load shedding strategy, the more it seems overly complicated. It's also another thing to fail. If the N.O. contactor coil fails, the loads to the house are going to lose power. That's not good for a remote installation. I guess you have to weigh battery protection with how critical the loads are. 

I'm wondering why the internal Battery Preservation Mode isn't sufficient enough. What's the purpose of load shedding if the BPM does effectively the same thing. I can see perhaps shedding some parts of the load and that is a nice feature, but to protect the batteries, why isn't BPM enough? 

Jason 

On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote: 
Hi Jason, 

I have done this with mercury displacement relays: 
https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp [1] 

They do have a 100A 2P 48V coil relay.  They seem to work perfectly. 

Good luck 

On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski  wrote: 
Does anyone know where I can get a load shedding contactor described in SMA documentation for use with a multi-function relay in a Sunny Island? 

Thanks, 


Jason Szumlanski  ___
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[8]

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Jason Szumlanski]

No, I would not use a Sol-Ark unless it was redundant, as in two paralleled
for AC output. I agree with you.

That's the other advantage of AC Coupling in a dual Sol-Ark configuration.
If done right the "extra" AC coupled PV can be usable in the event of a
single inverter failure (to an extent). But I don't have enough experience
with it to know for sure if this is a viable option.

Jason




On Thu, Jan 21, 2021, 5:34 PM Dave Angelini Offgrid Solar <
offgridso...@sti.net> wrote:

> Hi Jason,
>
> The downside of an all-in one, that may be acceptable for grid, is in a
> failure an all-in-one becomes unusable unless there is a spare. Even with
> one it is often a bigger job to deal with. This was my feedback to
> Schneider when they were looking into this 5 years back. I know they made
> the right decision for offgrid.[image: Wink]
>
>
>
> *Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/ 
> e-mail  offgridso...@sti.net 
> text 209 813 0060*
>
> On Thu, 21 Jan 2021 16:05:44 -0500, Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>
> It's already built - 6 years old - I didn't do it. The new property owner
> just purchased a very expensive battery bank and wants to protect it,
> understandably, because she had problems with her generator not starting as
> expected when not at the property. It was suggested by the original
> installer to install a load shedding contactor as the manual suggests
> (albeit in an opaque manner). I just can't seem to wrap my head around why
> this is a good idea. The integrated battery protection mode should handle
> this function. A contactor (or series of relays and a contactor) carries
> too much risk of failure that could result in another problem for the owner
> altogether. I understand protecting the battery, but the cure can't be
> worse than the disease. I'm looking for a balanced approach, which I
> believe is to just implement the BPM unless I'm missing some deficiency in
> that strategy.
>
> The system worked great in an AC coupled configuration until the generator
> started becoming unreliable. In Florida I like AC coupling in a scenario
> like this where the most challenging load is in the summer, essentially
> concurrent with peak sunlight (air conditioning). However, I have been
> looking at trying out a Sol-Ark as soon as the opportunity arises with a
> combination of DC and AC coupling. With no separate charge controller
> involved, it becomes much less complicated and you get the best of both
> worlds in theory.
>
> Jason
>
>
>
>
> On Thu, Jan 21, 2021 at 3:36 PM Tump  wrote:
>
>> IF this system has yet to be built I would STRONGLY suggest that AC
>> coupling is NOT considered. IF it is them i would consider HV CC DC
>> coupling.
>> T
>>
>> On Jan 21, 2021, at 3:15 PM, Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>>
>> Hi Mac,
>>
>> Yes, I considered using a pilot relay - it makes sense to run it on 120V
>> because relays are readily available. I had the exact same concern - more
>> to fail.
>>
>> In this scenario, the inverter/battery room is remote from the house so
>> there is only one load I can switch easily with a contactor, and that's the
>> whole house load. Otherwise, I would definitely consider switching
>> non-critical loads in a low battery situation.
>>
>> It just seems prudent enough to use the integrated Battery
>> Preservation Mode (BPM), even in this AC coupled system. I considered a
>> small DC array to charge the batteries in a heavily depleted situation, but
>> it's a 60kWh battery so I would need a pretty substantial "backup" array I
>> think. It does not seem like a reasonable solution. I would expect BPM to
>> do it's job and keep the batteries from reaching a state that they are not
>> recovered quite easily.
>>
>> Jason
>>
>>
>> On Thu, Jan 21, 2021 at 2:37 PM Mac Lewis  wrote:
>>
>>> Hi Jason,
>>>
>>> The only reason to load shed, without using the internal preservation
>>> mode is if you have certain loads you'd like to keep on longer than other
>>> loads that you shed.  The various preservation modes can be complex,
>>> especially if you are AC coupled, so you really have to think through your
>>> strategy.
>>>
>>> You can always use a pilot relay, with a coil rating that suits your
>>> needs, and then feed the 100A contactor with that.  Unfortunately, its just
>>> one more piece to fail...
>>>
>>> On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski <
>>> ja...@floridasolardesigngroup.com> wrote:
>>>
 I just learned from the manufacturer that the mercury displacement
 relay's coil is rated for 43.2 to 52.80V. Obviously, the battery voltage
 can exceed 52.8 pretty significantly. Does the Sunny Island regulate the
 output voltage on this relay to 48V or is the actual battery voltage passed
 through on this terminal?

 The more I read about this load shedding strategy, the more it seems

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Dave Angelini Offgrid Solar]

Hi Jason, 

The downside of an all-in one, that may be acceptable for
grid, is in a failure an all-in-one becomes unusable unless there is a
spare. Even with one it is often a bigger job to deal with. This was my
feedback to Schneider when they were looking into this 5 years back. I know
they made the right decision for offgrid.  

Dave Angelini Offgrid
Solar
"we go where powerlines don't"
http://members.sti.net/offgridsolar/
[1]
e-mail offgridso...@sti.net [2]
text 209 813 0060

On Thu, 21 Jan 2021
16:05:44 -0500, Jason Szumlanski  wrote:  It's already built - 6 years
old - I didn't do it. The new property owner just purchased a very
expensive battery bank and wants to protect it, understandably, because she
had problems with her generator not starting as expected when not at the
property. It was suggested by the original installer to install a load
shedding contactor as the manual suggests (albeit in an opaque manner). I
just can't seem to wrap my head around why this is a good idea. The
integrated battery protection mode should handle this function. A contactor
(or series of relays and a contactor) carries too much risk of failure that
could result in another problem for the owner altogether. I understand
protecting the battery, but the cure can't be worse than the disease. I'm
looking for a balanced approach, which I believe is to just implement the
BPM unless I'm missing some deficiency in that strategy.   The system
worked great in an AC coupled configuration until the generator started
becoming unreliable. In Florida I like AC coupling in a scenario like this
where the most challenging load is in the summer, essentially concurrent
with peak sunlight (air conditioning). However, I have been looking at
trying out a Sol-Ark as soon as the opportunity arises with a combination
of DC and AC coupling. With no separate charge controller involved, it
becomes much less complicated and you get the best of both worlds in
theory.   Jason  
  On Thu, Jan 21, 2021 at 3:36 PM
Tump  wrote:  IF this system has yet to be built I would STRONGLY suggest
that AC coupling is NOT considered. IF it is them i would consider HV CC DC
coupling. T
   On Jan 21, 2021, at 3:15 PM, Jason Szumlanski  wrote: 
 
Hi Mac,   Yes, I considered using a pilot relay - it makes sense to run it
on 120V because relays are readily available. I had the exact same concern
- more to fail.In this scenario, the inverter/battery room is remote
from the house so there is only one load I can switch easily with a
contactor, and that's the whole house load. Otherwise, I would definitely
consider switching non-critical loads in a low battery situation.It
just seems prudent enough to use the integrated Battery Preservation Mode
(BPM), even in this AC coupled system. I considered a small DC array to
charge the batteries in a heavily depleted situation, but it's a 60kWh
battery so I would need a pretty substantial "backup" array I think. It
does not seem like a reasonable solution. I would expect BPM to do it's job
and keep the batteries from reaching a state that they are not recovered
quite easily.   Jason  
  On Thu, Jan 21, 2021 at 2:37
PM Mac Lewis  wrote:  Hi Jason,   The only reason to load shed, without
using the internal preservation mode is if you have certain loads you'd
like to keep on longer than other loads that you shed. The various
preservation modes can be complex, especially if you are AC coupled, so you
really have to think through your strategy.   You can always use a pilot
relay, with a coil rating that suits your needs, and then feed the 100A
contactor with that. Unfortunately, its just one more piece to fail...  
 
On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski  wrote:I just learned
from the manufacturer that the mercury displacement relay's coil is rated
for 43.2 to 52.80V. Obviously, the battery voltage can exceed 52.8 pretty
significantly. Does the Sunny Island regulate the output voltage on this
relay to 48V or is the actual battery voltage passed through on this
terminal?   The more I read about this load shedding strategy, the more it
seems overly complicated. It's also another thing to fail. If the N.O.
contactor coil fails, the loads to the house are going to lose power.
That's not good for a remote installation. I guess you have to weigh
battery protection with how critical the loads are.   I'm wondering why the
internal Battery Preservation Mode isn't sufficient enough. What's the
purpose of load shedding if the BPM does effectively the same thing. I can
see perhaps shedding some parts of the load and that is a nice feature, but
to protect the batteries, why isn't BPM enough?   Jason
  
  On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:  Hi Jason,   I have
done this with mercury displacement relays:
https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
[8]   They do have a 100A 2P 48V coil relay. They seem to 

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Jason Szumlanski]

It's already built - 6 years old - I didn't do it. The new property owner
just purchased a very expensive battery bank and wants to protect it,
understandably, because she had problems with her generator not starting as
expected when not at the property. It was suggested by the original
installer to install a load shedding contactor as the manual suggests
(albeit in an opaque manner). I just can't seem to wrap my head around why
this is a good idea. The integrated battery protection mode should handle
this function. A contactor (or series of relays and a contactor) carries
too much risk of failure that could result in another problem for the owner
altogether. I understand protecting the battery, but the cure can't be
worse than the disease. I'm looking for a balanced approach, which I
believe is to just implement the BPM unless I'm missing some deficiency in
that strategy.

The system worked great in an AC coupled configuration until the generator
started becoming unreliable. In Florida I like AC coupling in a scenario
like this where the most challenging load is in the summer, essentially
concurrent with peak sunlight (air conditioning). However, I have been
looking at trying out a Sol-Ark as soon as the opportunity arises with a
combination of DC and AC coupling. With no separate charge controller
involved, it becomes much less complicated and you get the best of both
worlds in theory.

Jason





On Thu, Jan 21, 2021 at 3:36 PM Tump  wrote:

> IF this system has yet to be built I would STRONGLY suggest that AC
> coupling is NOT considered. IF it is them i would consider HV CC DC
> coupling.
> T
>
> On Jan 21, 2021, at 3:15 PM, Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
> Hi Mac,
>
> Yes, I considered using a pilot relay - it makes sense to run it on 120V
> because relays are readily available. I had the exact same concern - more
> to fail.
>
> In this scenario, the inverter/battery room is remote from the house so
> there is only one load I can switch easily with a contactor, and that's the
> whole house load. Otherwise, I would definitely consider switching
> non-critical loads in a low battery situation.
>
> It just seems prudent enough to use the integrated Battery
> Preservation Mode (BPM), even in this AC coupled system. I considered a
> small DC array to charge the batteries in a heavily depleted situation, but
> it's a 60kWh battery so I would need a pretty substantial "backup" array I
> think. It does not seem like a reasonable solution. I would expect BPM to
> do it's job and keep the batteries from reaching a state that they are not
> recovered quite easily.
>
> Jason
>
>
>
> On Thu, Jan 21, 2021 at 2:37 PM Mac Lewis  wrote:
>
>> Hi Jason,
>>
>> The only reason to load shed, without using the internal preservation
>> mode is if you have certain loads you'd like to keep on longer than other
>> loads that you shed.  The various preservation modes can be complex,
>> especially if you are AC coupled, so you really have to think through your
>> strategy.
>>
>> You can always use a pilot relay, with a coil rating that suits your
>> needs, and then feed the 100A contactor with that.  Unfortunately, its just
>> one more piece to fail...
>>
>> On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>>> I just learned from the manufacturer that the mercury displacement
>>> relay's coil is rated for 43.2 to 52.80V. Obviously, the battery voltage
>>> can exceed 52.8 pretty significantly. Does the Sunny Island regulate the
>>> output voltage on this relay to 48V or is the actual battery voltage passed
>>> through on this terminal?
>>>
>>> The more I read about this load shedding strategy, the more it seems
>>> overly complicated. It's also another thing to fail. If the N.O. contactor
>>> coil fails, the loads to the house are going to lose power. That's not good
>>> for a remote installation. I guess you have to weigh battery protection
>>> with how critical the loads are.
>>>
>>> I'm wondering why the internal Battery Preservation Mode isn't
>>> sufficient enough. What's the purpose of load shedding if the BPM does
>>> effectively the same thing. I can see perhaps shedding some parts of the
>>> load and that is a nice feature, but to protect the batteries, why isn't
>>> BPM enough?
>>>
>>> Jason
>>>
>>>
>>>
>>>
>>> On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:
>>>
 Hi Jason,

 I have done this with mercury displacement relays:

 https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
 

 They do have a 100A 2P 48V coil relay.  They seem to work perfectly.

 Good luck

 On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
 ja...@floridasolardesigngroup.com> wrote:

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Tump]

IF this system has yet to be built I would STRONGLY suggest that AC coupling is 
NOT considered. IF it is them i would consider HV CC DC coupling.
T
> On Jan 21, 2021, at 3:15 PM, Jason Szumlanski 
>  wrote:
> 
> Hi Mac,
> 
> Yes, I considered using a pilot relay - it makes sense to run it on 120V 
> because relays are readily available. I had the exact same concern - more to 
> fail. 
> 
> In this scenario, the inverter/battery room is remote from the house so there 
> is only one load I can switch easily with a contactor, and that's the whole 
> house load. Otherwise, I would definitely consider switching non-critical 
> loads in a low battery situation. 
> 
> It just seems prudent enough to use the integrated Battery Preservation Mode 
> (BPM), even in this AC coupled system. I considered a small DC array to 
> charge the batteries in a heavily depleted situation, but it's a 60kWh 
> battery so I would need a pretty substantial "backup" array I think. It does 
> not seem like a reasonable solution. I would expect BPM to do it's job and 
> keep the batteries from reaching a state that they are not recovered quite 
> easily.
> 
> Jason
> 
> 
> 
> On Thu, Jan 21, 2021 at 2:37 PM Mac Lewis  > wrote:
> Hi Jason,
> 
> The only reason to load shed, without using the internal preservation mode is 
> if you have certain loads you'd like to keep on longer than other loads that 
> you shed.  The various preservation modes can be complex, especially if you 
> are AC coupled, so you really have to think through your strategy.
> 
> You can always use a pilot relay, with a coil rating that suits your needs, 
> and then feed the 100A contactor with that.  Unfortunately, its just one more 
> piece to fail...
> 
> On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski 
>  > wrote:
> I just learned from the manufacturer that the mercury displacement relay's 
> coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed 
> 52.8 pretty significantly. Does the Sunny Island regulate the output voltage 
> on this relay to 48V or is the actual battery voltage passed through on this 
> terminal?
> 
> The more I read about this load shedding strategy, the more it seems overly 
> complicated. It's also another thing to fail. If the N.O. contactor coil 
> fails, the loads to the house are going to lose power. That's not good for a 
> remote installation. I guess you have to weigh battery protection with how 
> critical the loads are.
> 
> I'm wondering why the internal Battery Preservation Mode isn't sufficient 
> enough. What's the purpose of load shedding if the BPM does effectively the 
> same thing. I can see perhaps shedding some parts of the load and that is a 
> nice feature, but to protect the batteries, why isn't BPM enough?
> 
> Jason
> 
> 
> 
> 
> On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  > wrote:
> Hi Jason,
> 
> I have done this with mercury displacement relays:
> https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
>  
> 
> 
> They do have a 100A 2P 48V coil relay.  They seem to work perfectly.
> 
> Good luck
> 
> On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski 
>  > wrote:
> Does anyone know where I can get a load shedding contactor described in SMA 
> documentation for use with a multi-function relay in a Sunny Island?
> 
> Thanks,
> 
> Jason Szumlanski 
> ___
> List sponsored by Redwood Alliance
> 
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Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Jason Szumlanski]

Hi Mac,

Yes, I considered using a pilot relay - it makes sense to run it on 120V
because relays are readily available. I had the exact same concern - more
to fail.

In this scenario, the inverter/battery room is remote from the house so
there is only one load I can switch easily with a contactor, and that's the
whole house load. Otherwise, I would definitely consider switching
non-critical loads in a low battery situation.

It just seems prudent enough to use the integrated Battery
Preservation Mode (BPM), even in this AC coupled system. I considered a
small DC array to charge the batteries in a heavily depleted situation, but
it's a 60kWh battery so I would need a pretty substantial "backup" array I
think. It does not seem like a reasonable solution. I would expect BPM to
do it's job and keep the batteries from reaching a state that they are not
recovered quite easily.

Jason



On Thu, Jan 21, 2021 at 2:37 PM Mac Lewis  wrote:

> Hi Jason,
>
> The only reason to load shed, without using the internal preservation mode
> is if you have certain loads you'd like to keep on longer than other loads
> that you shed.  The various preservation modes can be complex, especially
> if you are AC coupled, so you really have to think through your strategy.
>
> You can always use a pilot relay, with a coil rating that suits your
> needs, and then feed the 100A contactor with that.  Unfortunately, its just
> one more piece to fail...
>
> On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> I just learned from the manufacturer that the mercury displacement
>> relay's coil is rated for 43.2 to 52.80V. Obviously, the battery voltage
>> can exceed 52.8 pretty significantly. Does the Sunny Island regulate the
>> output voltage on this relay to 48V or is the actual battery voltage passed
>> through on this terminal?
>>
>> The more I read about this load shedding strategy, the more it seems
>> overly complicated. It's also another thing to fail. If the N.O. contactor
>> coil fails, the loads to the house are going to lose power. That's not good
>> for a remote installation. I guess you have to weigh battery protection
>> with how critical the loads are.
>>
>> I'm wondering why the internal Battery Preservation Mode isn't sufficient
>> enough. What's the purpose of load shedding if the BPM does effectively the
>> same thing. I can see perhaps shedding some parts of the load and that is a
>> nice feature, but to protect the batteries, why isn't BPM enough?
>>
>> Jason
>>
>>
>>
>>
>> On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:
>>
>>> Hi Jason,
>>>
>>> I have done this with mercury displacement relays:
>>>
>>> https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
>>> 
>>>
>>> They do have a 100A 2P 48V coil relay.  They seem to work perfectly.
>>>
>>> Good luck
>>>
>>> On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
>>> ja...@floridasolardesigngroup.com> wrote:
>>>
 Does anyone know where I can get a load shedding contactor described in
 SMA documentation for use with a multi-function relay in a Sunny Island?

 Thanks,

 Jason Szumlanski
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>>>
>>> --
>>>
>>>
>>>
>>> Mac Lewis
>>>
>>> *"Yo solo sé que no 

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Mac Lewis]

Hi Jason,

The only reason to load shed, without using the internal preservation mode
is if you have certain loads you'd like to keep on longer than other loads
that you shed.  The various preservation modes can be complex, especially
if you are AC coupled, so you really have to think through your strategy.

You can always use a pilot relay, with a coil rating that suits your needs,
and then feed the 100A contactor with that.  Unfortunately, its just one
more piece to fail...

On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> I just learned from the manufacturer that the mercury displacement relay's
> coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed
> 52.8 pretty significantly. Does the Sunny Island regulate the output
> voltage on this relay to 48V or is the actual battery voltage passed
> through on this terminal?
>
> The more I read about this load shedding strategy, the more it seems
> overly complicated. It's also another thing to fail. If the N.O. contactor
> coil fails, the loads to the house are going to lose power. That's not good
> for a remote installation. I guess you have to weigh battery protection
> with how critical the loads are.
>
> I'm wondering why the internal Battery Preservation Mode isn't sufficient
> enough. What's the purpose of load shedding if the BPM does effectively the
> same thing. I can see perhaps shedding some parts of the load and that is a
> nice feature, but to protect the batteries, why isn't BPM enough?
>
> Jason
>
>
>
>
> On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:
>
>> Hi Jason,
>>
>> I have done this with mercury displacement relays:
>>
>> https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
>> 
>>
>> They do have a 100A 2P 48V coil relay.  They seem to work perfectly.
>>
>> Good luck
>>
>> On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>>> Does anyone know where I can get a load shedding contactor described in
>>> SMA documentation for use with a multi-function relay in a Sunny Island?
>>>
>>> Thanks,
>>>
>>> Jason Szumlanski
>>> ___
>>> List sponsored by Redwood Alliance
>>>
>>> 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
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>>>
>>> There are two list archives for searching. When one doesn't work, try
>>> the other:
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>>> 
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>>> 
>>>
>>> List rules & etiquette:
>>> http://www.re-wrenches.org/etiquette.htm
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>>>
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>>> http://www.members.re-wrenches.org
>>> 
>>>
>>>
>>
>> --
>>
>>
>>
>> Mac Lewis
>>
>> *"Yo solo sé que no sé nada." -Sócrates*
>> ___
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
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>> 

Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Jason Szumlanski]

I just learned from the manufacturer that the mercury displacement relay's
coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed
52.8 pretty significantly. Does the Sunny Island regulate the output
voltage on this relay to 48V or is the actual battery voltage passed
through on this terminal?

The more I read about this load shedding strategy, the more it seems overly
complicated. It's also another thing to fail. If the N.O. contactor coil
fails, the loads to the house are going to lose power. That's not good for
a remote installation. I guess you have to weigh battery protection with
how critical the loads are.

I'm wondering why the internal Battery Preservation Mode isn't sufficient
enough. What's the purpose of load shedding if the BPM does effectively the
same thing. I can see perhaps shedding some parts of the load and that is a
nice feature, but to protect the batteries, why isn't BPM enough?

Jason




On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis  wrote:

> Hi Jason,
>
> I have done this with mercury displacement relays:
>
> https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp
> 
>
> They do have a 100A 2P 48V coil relay.  They seem to work perfectly.
>
> Good luck
>
> On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> Does anyone know where I can get a load shedding contactor described in
>> SMA documentation for use with a multi-function relay in a Sunny Island?
>>
>> Thanks,
>>
>> Jason Szumlanski
>> ___
>> List sponsored by Redwood Alliance
>>
>> 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
>> 
>>
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>> http://www.re-wrenches.org/etiquette.htm
>> 
>>
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>> http://www.members.re-wrenches.org
>> 
>>
>>
>
> --
>
>
>
> Mac Lewis
>
> *"Yo solo sé que no sé nada." -Sócrates*
> ___
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
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Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[drake . chamberlin]

The mercury displacement relays are very robust. They do have a lead
warning.  


---

On 2021-01-19 20:48, Mac Lewis wrote:

Hi Jason, 

I have done this with mercury displacement relays: 
https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp 

They do have a 100A 2P 48V coil relay.  They seem to work perfectly. 

Good luck 

On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski  wrote: 

Does anyone know where I can get a load shedding contactor described in SMA documentation for use with a multi-function relay in a Sunny Island? 

Thanks, 


Jason Szumlanski  ___
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--

Mac Lewis

"Yo solo sé que no sé nada." -Sócrates 
___

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Re: [RE-wrenches] SMA Load Shedding Contactor 100A, 2P

[Mac Lewis]

Hi Jason,

I have done this with mercury displacement relays:
https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp

They do have a 100A 2P 48V coil relay.  They seem to work perfectly.

Good luck

On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> Does anyone know where I can get a load shedding contactor described in
> SMA documentation for use with a multi-function relay in a Sunny Island?
>
> Thanks,
>
> Jason Szumlanski
> ___
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-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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