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Brand New 12v / 100Amps Digital Rectifier is not working?

June 2, 2008

Hello,

I bought brand new 12V 100amps digital rectifier with digital timer, digital ampere min
meter, meters are not working while plating.

Only voltage meter is changing.

I'm able to do plating but figure is not changing.

Rectifier is single phase.

We checked Contactor Coil it is ok

Can anybody explaining me why it is not working, supplier have not send me manual and he is not sure what is the problem.

please help me.

Thank you.

Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania

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June 3, 2008

Hi, Dipen. Ampere meters and ampere hour meters are not "really" ampere meters, they are really 50 mV voltmeters. How they work is there should be a block of copper-like material at the bus bar connection of the rectifier that is a very precise size, shape, and resistivity, and which is called a shunt. When 1000 Amps is flowing, the voltage drop across this shunt (Ohm's Law) will be 50 mV. You will find a need to connect the ampere meter wires to this shunt. Of course, the rectifier supplier may have omitted the shunt as a cost-saving idea or in error :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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June 6, 2008

Hello Ted,

Thanks for your advice and I'll go through as you said.

Today I have got manual from my supplier and I have show one of my technical person as he is seeing first time in his field, in diagram shows volt + wire goes to shunt but in rectifier it is not going.

I have asked my supplier do we change because my technical person is worry better to ask supplier.

I'll also tell to supplier what Ted advice me.
I'll get back with more answers.

Thanks

Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania

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July 3, 2008

Hi,

My supplier told me to change amp and ampere time meters which they have send me and we changed but still problem is there.

All the wiring seems okay as per diagram, I don't no what is the problem now.

Can anybody help me.

Dipen Pattni

Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania

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It is very difficult for anyone from this distance to guess what is broken and/or miswired or missing, Dipen. But measure the voltage across the shunt with a portable VOM multimeter [on eBay or Amazon] and tell us what you got at what estimated amperage.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 6, 2008

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July 9, 2008

Today my technical person have got meter which came measure output current is working fine.

My technical person said may be in rectifier amp meter is bigger so smaller load won't show so he told me to plate something big. e.g S.S plate 8"x6" I tried to plate nickel and it was showing first time in rectifier 005 amp to 007 amp for 5 mins I tried and ampere time meter was also working but I have set 5mins in rectifier, I knew that counter is not perfect within 54 second 5 mins have over then buzzer started......... that means plating have is OFF.

Technical person meter was showing output 03.0 amp and I also try with my old rectifier which is 20amp 12volt it was showing me 2.85amps.

My amp meter is 000 there is no 000.00 it counts from 1amp.

Again I have tried to plat white gold ring with rhodium I have set 3.6 Volt and for about 5 mins which is 54seconds and in rectifier amp meter was showing 001 or 002, same ring I did plating with Rh by another older rectifier same voltage which was showing me 1.68amps or 1.93 amps.

I think I'll have to calibrate very small switches which is behind the ampere time meters. I had talked about this to my supplier.

I tried in both meters old and new result was same so meters are working.

Still I'll let you know what solution I have got.

Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania