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

Thu Jan 21 13:59:13 EST 2021

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 <maclewis1 at gmail.com> 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
> <https://mailtrack.io/trace/link/507c3cd242097f112c86a155d1e20d50857a422b?url=https%3A%2F%2Fwww.mdius.com%2Fmercury-relays%2Ftwo-pole-relays-contactors%2Ftwo-pole-100-amp&userId=1613865&signature=1f785f791758ce12>
>
> 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 <
> jason at 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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