Varistors

[John Szegda]

Hello Rob,

Hope everything is well with you. I had my controller offline to do some panel work. When I powered up the controller a gust of wind caused the turbine to free wheel 782V
DC , consequently frying one varistor mov in the Aurora 3.6. I'm hoping by replacing the movs, I can fix the unit myself. When I removed the white plastic inserts, I damaged a few. I have been searching, but can not find them. Do you know what there called and where I can purchase them

John

[Andy Rhody]

Sorry to hear John. Can you tell us more about your turbine like what is it's rated voltage?

[Rob Beckers]

Sorry to hear about the mishap John!
Could you post a picture of the "white plastic inserts". I don't know what you're referring to.

Does the inverter work after removing the MOVs?

-RoB-

[John Szegda]

Hi Rob and nice meeting you Andy.

I will get pictures loaded in the AM. If you look inside the Aurora Inverter you can see the white inserts inside the Mov mount. The small spring is not very rigid and these inserts are designed to put pressure on the Mov wire.

John

[John Szegda]

Hello Rob,

Enclosed is a picture of the white inserts we were talking about yesterday. I,m sure the 3.6 was still operative but at the time my main concern was to shut everyting down, to stop additional damage.

[Dave Turpin]

Bet I can find all the components you need on Digikey.com. There is probably text on the MOV themselves that you can use to do a search.

The little white things are just single pin jumpers; easy to get on Digikey, and probably not even necessary for operation of the inverter.

[John Szegda]

Hi Dave,

I bought my Movs from Digikey, but could not find inserts. If you can find a part number, I will be very appreciative.

John

[Dave Turpin]

On further inspection it looks like you have some quick-release spring clamp IC connectors there. Is there a manufacturer stamp anywhere on the black plastic part?

[John Szegda]

No markings at all. You would think the Littelfuse company make them for there Movs. I'll try Power One repair people in phoenix tomorrow.

John

[Rob Beckers]

John, those white thingies actually come with the 'foot' that the MOVs are placed in. They are compression contacts, opened/closed by turning them 90 degrees (if memory serves me). They don't come by themselves. You can try looking for an MOV foot or socket in Digikey's catalog.

What happened to the ones that you took out?

-RoB-

[John Szegda]

Rob,

There was only one mov that blow . No exaggeration, the mov sounded like a gun shot. When I clamped on to the insert, with slight pressure, it disintegrated. I guess they heat up and become brittle. If I"m not able to locate them, I'll cut small pieces of #10 bare copper wire and insert them in the socket and put a bit of high temp silicone on top to secure them in place.

John

[Dave Turpin]

I couldn't find the exact same socket in the catalog, but several similar ones, under spring-loaded through-hole wire-to-board sockets. There are bound to be markings on your socket somewhere, probably where you can't see while installed.

You are probably better off just doing your above plan to jury-rig the MOV in place, otherwise you would probably need to desolder and replace the damaged ones...

[John Szegda]

Dave,

Thanks for your time. I used #14 bare copper wire about 5/16" long and inserted them in the slots. Then I used high temp silicone for added staying protection.

John

[John Szegda]

Hello Every One,

I have a Aurora 3.6 that spiked over 700VDC. Instead of sending the unit to Power One, I replaced two fried Movs. I put the Inverter online today and it works perfectly. I'm happy, this saved me all most $1,000. with shipping. I guess these Aurora Inverters are not as fragile as some people think.

John

[Rob Beckers]

You got lucky John. I've seen quite a few blow inverters, and the issue wasn't the MOVs. Moreover, the inverter will log in memory that the voltage exceeded 600V DC, voiding the warranty...

I would strongly suggest not to repeat the experiment. The outcome will not always be the same.:eek:

-RoB-