question

dean-d avatar image
dean-d asked

AC input external contactor - large supply

We have a 3-phase installation with 3x 5kW Multiplus 2.

The supply is 160A per phase. The MP2 can pass through 50A per phase.

Is it possible to use an external contactor, which drops out, so the loads can be fed by the MP2 during grid operation? but isolate the grid in an outage.

The reason for this is we cant pass the whole supply through the MP2.

Multiplus-IIgrid
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2 Answers
Paul B avatar image
Paul B answered ·

the units are not correct for the job - to small for the project you should really have 2 x multiplus 5000 units in parallel per phase not a multiplus ii this would then give passthrough of 200amps as 160 amps per phase will damage the units relays on your current multiplus II.

doing bypass relays how and when, you would have to look at this yourself, and design a circuit that worked for you, you would then have dropout issues on power outages as if you are using 160 amps per phase then the multis just cant do that

but to have auto switch over etc would not work.


anyway its just wont work unless you limit the input current to max 50 amps per phase for those units.

you could parallel 3x on each phase and that would give you 150 amps passthrough

or

you could parallel 4x on each phase and that would give you 200 amps passthrough








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Alexandra avatar image
Alexandra answered ·

@Dean_D

No, since the relays are only designed for less than 1/3 of the connection. It is still transferring the power through its internal transfer switch even if you use an external contactor. That would be like having a 20A breaker on a circuit that uses 60A.

Choose circuits to support, or resize the system.

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