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Voltage rise in rectifiers for electroplating

What is the main reason of voltage rise of rectifier in case there is a depletion of anode shots in electroplating? What theory(ies) or mathematical formula(s) can explain this phenomena?

Thanks,

Jessie R. Salvanera
- Lapu-lapu City, Cebu, Philippines
2003

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Unfortunately you have posted this as an abstract question rather than as your real-world situation, Mr. Salvanera. So the best you will get is answers which may be good in the abstract but poor in the real world. Some metals polarize at high current density; that is, the electrons available to oxidize them and dissolve them into solution, tend to convert the metal surface to an insulating oxide film instead at high current density. Also, with a smaller surface area available, the ions have to travel a longer path from the anode to the cathode, meaning more resistance, meaning more voltage required to sustain the current. Get back to us with more details.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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First, you should not let that happen as lots of bad things can result.

Your power supply is putting out a given amount of amps for the selected voltage. When you reach a critical point of not having enough anode in solution, the amperage will drop some, as the anode can no longer transfer that amperage. To keep the power supply balanced, it will go up slightly in voltage unless you have a constant voltage power supply (which I highly doubt).

James Watts
- Navarre, Florida
2003