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Parallel SCR Board


Boela

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Hi there,

What is the function of the Parallel SCR Board in a Kodak (Axpert) inverter?

Mine got fried and this caused the MPPT 1 side not to see the array any longer, however MPPT 2 worked fine. It seems the PV array was installed in series this caused the voltage to potentially go over 450v (VOC 47.9 x 10). 

 

image.png.8dad9917d43e62140fe329faf07d7dc6.png

I split the MPPT 1 array into 2 x 5, but just want to make sure this could be the only cause.

Thanks

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15 hours ago, Boela said:

What is the function of the Parallel SCR Board in a Kodak (Axpert) inverter?

My understanding is that when you have set the AC input range to UPS, this board uses semiconductors (Silicon Controlled Rectifiers) so speed up switchover from grid to/from battery. The typical transfer time is claimed to reduce from 20 ms to 10 ms with this board.

In South Africa, with its notoriously unreliable grid and frequent load shedding, a lot of people use the APL input voltage range setting, which I believe means that this board does nothing and could simply be removed. But I've never proven that belief by actually trying it out.

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27 minutes ago, Coulomb said:

My understanding is that when you have set the AC input range to UPS, this board uses semiconductors (Silicon Controlled Rectifiers) so speed up switchover from grid to/from battery. The typical transfer time is claimed to reduce from 20 ms to 10 ms with this board.

In South Africa, with its notoriously unreliable grid and frequent load shedding, a lot of people use the APL input voltage range setting, which I believe means that this board does nothing and could simply be removed. But I've never proven that belief by actually trying it out.

Yes, I can confirm that  the inverter still operates when the module is  removed, no warning, no error.  

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Funny that when it failed, the MPPT 1 of the dual input stop working - even swopped the connectors between 1 and 2, same result.

Replaced the board, and Mppt 1 is working again telling me that I need to have this part in. Does it do any balancing between the inputs i.e. if 1 input as before was 430-470v and the other hovering at 320v relate to the burning of the components?

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10 hours ago, Boela said:

Does it do any balancing between the inputs i.e. if 1 input as before was 430-470v and the other hovering at 320v relate to the burning of the components?

No. The MPPTs are totally separate.

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You can select Appliance or UPS, mine is on Appliance.

 

Still very strange that the MPPT 1 stop working after this board packed up but more so, want to understand what caused this and how do I prevent it from happening again. Currently running smooth with new board with Mppt 1 on 208v and MPPT 2 on 321v

I have also noticed recently the AC side from Eskom and then inverter ranges between 228v and 243v via the Watchpower app

 

image.thumb.png.bc35bd51628f35eff01b7ce26986b891.png

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6 hours ago, Boela said:

Still very strange that the MPPT 1 stop working after this board packed up

Indeed, since this board is connected only (apart from small signal data) to the AC side (grid and inverter output). I guess that this could cause a fluctuation in the DC bus voltage via the free-wheel diodes of the DC-AC full bridge IGBTs, and the solar charge controller (for these models) connects to the DC bus.

6 hours ago, Boela said:

how do I prevent it from happening again

I've not heard of these boards giving trouble. Perhaps you were just unlucky.

6 hours ago, Boela said:

I have also noticed recently the AC side from Eskom and then inverter ranges between 228v and 243v

That seems OK, I don't think it explains the problem. I'd be more inclined to suspect transients caused by turning on and especially off large inductive loads at the start and end of load shedding.

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