Solar Controller 12/24 V

[bob.steel]

I have blown my controller by putting too much voltage into it via the PV panels 67 volts instead of under 50 .

Looking inside I see only one component is toast . It is marked on the board as ZR1
I assume its a zener although the package looks like a polyswitch.

What do you think it would be as I wish to replace it as everything else on the board looks good and the bad charring cleaned up remarkably well.

Would it be a 12V zener? Could a polyswitch be used there?

 

[Harald Kapp]

ZR is probably and looks like a varistor (also called MOV). If the board works after removing the MOV, put in a replacement and you should be good.
However, there's usually more damage. I'd expect at least a fuse in front of the MOV (between MOV and input terminals) to be blown. Without a fuse the MOV doesn't make much sense.
As for the correct replacement one would need to know the type that was originally used. Lacking a schematic this is almost impossible.

 

[bob.steel]

Some more pics
Ridiculous . Why wait until the whole file is uploaded before saying

The following error occurred
There was a problem uploading your file.
IMG_20200401_163844.jpg

Obviously you have a size limit but why not put the size on the error notice

Where do I find the size limit?

 

[Harald Kapp]

why not put the size on the error notice

Because we do not know exactly. about 100 kB is usually o.k. But as you can see from your first post 256 kB works also. I'm sorry I have no definitive answer .

 

[bob.steel]

No sweat . Thanks. I resized but there are a couple more I will try to put up .
Can you take a stab at a value I could try? I can't get a circuit . Input voltage is said to be 50V max . I don't see any obvious fuse . Current from the panels will be about 16 Amps max and 66 Volts max

 

[Harald Kapp]

A MOV rated for 85 V DC might be suitable. A 70 V DC MOV may be a bit too close to the max. output voltage of the panel.
In any case, before you replace the MOC remove the old one and check the operation of the regulator. The MOC is a protection device and in normal operation is inactive. But a short circuit of the MOV will blow the fuse. That's what these components are for.
If the rest of the pcb is fine, then insert a new MOV. Do not operate the pcb without protection in normal use.

 

[bob.steel]

Ok fine . Learnt a new device today . Cant get much better days than that.
The controller works fine once the MOV was removed so Ill try to get a replacement and put it in. Thanks again .

 

[73's de Edd]

Sir bob.steel . . . . .

Looking at your PCB foil paths, that Varistor is being placed across from your solar bank input to ground plane.
I cherry picked the units on the suppliers options and I believe that the original unit is going to be / was a 40 /56V unit which starts avalanching at 40Volts AC or 56 VDC, the latter voltage of which, is YOUR UNITS situation.
That PUFFED up unit has some serious overload subjected to it for a time. BUNCH of GOOD sunny days.
If you look at this major suppliers stock level of different varistor units you will find MASSIVE stock levels of 120 and 230 units, such as those what are used in line operated electrial equipment and AC power strips.
And then there are fast movers down in the battery voltage ranges.
AND THEN . . . there is the solar community and the popular choice of 48 V as the collectors output.
Check their stock level and you will see the particular and noticeable 3674 ---2965---1694 and 1308 units in stock. MOVERS !
The other aspect is the units power rating and that is dependent upon the diameter of the ZnO2 slug being used . . . .7---10----14--- and a final 20 mm.
By memory you should be able to differentiate as to the diameter of the original NAKED slug. . . .or you may able to reconstruct with the original units scraps.
The side leads bondings are those units real Achilles heel, but most, additionally rely upon a form fitting conformal coating for their extra protection, yours looked to be vinyl, but it just " couldn't take the heat " anymore.
If your NOW black covering might show traces of a different original color, that might tie into the original units brand, others use BLACK for Panasonic . . . LITTLEFUSE and GE use RED . . . Bourns / EPCO use BLUE .
If my problem to solve I would be using use the heftiest 20mm slug size.
BUT in / if trying to go one step up in the initial voltage rating, just might then put you in harms way.

VARISTOR REFERENCING . . . . .
https://www.newark.com/w/c/circuit-...stor-case-style=disc-10mm|disc-14mm|disc-20mm

73's de Edd . . . . .

My E-mail password has been hacked again. That's now the third time I've had to rename the dog . . . now he just looks at me and gives me that quizzical, cocked head look.



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[roughshawd]

On my hacked out solar board, the builder used a monster diode to handle the power. I never got it to work yet, because I melted a switch when I was soldering that I was putting in it to turn it on and off.
It is a huge one.. I'll take a pic.

 

[debe]

This is your MOV, have the same regulators.

 

[73's de Edd]

Sires . . . . .

Three cheers and praise be to our esteemed and honorable Debe for providing those critically needed numbers from a good varistor.
Now, along with the supplied data sheet . . . . all is now known.

Da Da Sheet . . . . .

Potentially time Limited Hot Link
https://i.ibb.co/jkpyQDd/Sintered-Zinc-Oxide-Varistors.png



Bob Steel . . . you still around ?

With the severity of damage to that unit, it looks like its system took a lightnig bolt hit.
That alone is possible to be the source of damage or it at least was being strong enough to get all of the slugs semiconductive sinter particules up to their conductive threshold and convert into a low resistance conductive condition . . . . then the voltage and current capacity of the system can CONTINUALLY flow through that conductive mass until breakdown / vaporization or the disruption / tripping of a fusing circuit feed ..


73's De Edd . . . . .


Confucius Say . . .
Jogger who run to keep in front of a car, he get tired . . . but . . . Jogger who lag behind car . . . . . he get exhausted.



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