AC relay fault, Did OB add more relays?

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AC relay fault, Did OB add more relays?

Postby kees.barendse on Wed Jan 11, 2017 11:38 pm

We have been having issues with intermittent AC relay faults on our three GS7048E Radian inverters. We have already replaced two relay boards where the relays burnt out when running the inverters at or close to the maximum 40 Amps output current, mostly due to run in currents of our machines like belt sanders and the like. Because we run out inverters in a three phase setup an AC relay fault on one of the inverters will cause the whole system to kick itself offline.

Our current AC relay boards have two relays, one for grid input and one for generator input. I noticed in an Outback instruction document which describes Radian board replacement procedures that currently Outback is delivering Radians with four relays! If that is the case, wouldn't it be nice if OB gave some kind of warranty on what appears to be a deficient design which has since been upgraded and improved upon..... ?

Here are the images that show the difference.

https://drive.google.com/file/d/0B_Wi1k ... sp=sharing
https://drive.google.com/file/d/0B_Wi1k ... sp=sharing

Regards,

Kees Barendse
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Re: AC relay fault, Did OB add more relays?

Postby Sandra Herrera on Thu Jan 12, 2017 9:43 am

Kees,
These are the two differences between 7048E and the North America model 8048.
In North America we have two phases L1 and L2, this is why you see 4 relays in the North America models and only 2 relays for the E models.
The relays for both models have a maximum current rating, and this must be consider during the design of the system.
Sandra Herrera
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Re: AC relay fault, Did OB add more relays?

Postby kees.barendse on Thu Jan 12, 2017 10:07 am

Dear Sandra,

Many thanks for the quick reply and the good explanation! I think you folk know better than I do whether other users of the 7048 inverters have issues with bad AC relays. Having had a closer look at those relays I would say that they seem a bit flimsy for the loads they are supposed to carry.

Let me find a way to change out this board one more time and confirm that we have the right output breakers now.

Regards,

Kees
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Re: AC relay fault, Did OB add more relays?

Postby blackswan555 on Thu Jan 12, 2017 10:15 am

Not my game but a thought or two, Are you using a powersave of any description ? usually if inrush current is high but the relay is already closed, not a problem ,

Tim
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Re: AC relay fault, Did OB add more relays?

Postby blackswan555 on Fri Jul 07, 2017 10:27 pm

Came across the below when looking for an old thread, Have a read from about half way down, Tallgirls post onwards, Could be a reason you are eating relays ? viewtopic.php?f=17&t=3380

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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Re: AC relay fault, Did OB add more relays?

Postby kees.barendse on Tue Nov 28, 2017 2:06 am

Thanks Tim,

Interesting reading.. What is also interesting is that OB apparently do not offer warranty replacements on the power boards if they fail due to an AC relay fault. This to me seems like an indication that OB might have some issues with those relays. One other reason I can see why the relays would fail is that they use three poles in parallel, but one can assume that there will always be one pole closing slightly before the others. The poles are rated at 30 amps each, and we regularly see steady amps of 35 Amps through our Radian. This would overload the first closing pole , which then arcs, increasing the resistance. This means the loads are now taken by the remaining two poles, which will also burn out over time. On some of the relays we see brown overheating damage in the casing, so there is definitely something going on there.

Our AC relays faults show up either on sudden high loads, like a vacuum cleaner, or when there are short dips in the grid supply. But by far the most annoying issue is that the inverter setting goes to OFF when one of the Radians on the system throws an AC relay fault. This means that during the duration of the AC relay fault (3 seconds) no power is supplied to the loads, and when the grid drops at any time after that the whole system goes offline.

I am considering soldering an identical relay in parallel across the existing relays. This would spread the loads over 6 poles, not three. However, it would also double the coil current and I am not sure the control circuitry can handle that...
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