As the co-owner of American Plating Power, Peter has over 30 years experience in the power electronics & metal plating industry.

Q: What are the advantages of Oil-Cooled Rectifiers?

A:  An enclosed liquid-cooling system can eliminate the corrosion/contamination risk posed by the air-cooled method. This solution is not only technically advanced, but also addresses the financial concerns related to investment and maintenance costs. Similar to substation transformers, mineral oil is used as a liquid coolant to dissipate heat and  eliminate any sparks that might be generated. As a result, the internal corrosion problems seen with forced air-stream methods are  eliminated. Oil or combined oil-to-water cooled rectifiers do not  require openings in the enclosure for the cooling process. The main power components are submerged into a corrugated steel tank filled with commonly used insulation oil. The natural convection of the oil inside the tank cools the components. The rectifier is well protected from the aggressive surrounding and potentially damaging air-borne particles. While air-cooled rectifiers require installation in a separate room or apart from the plating tanks, the oil-cooled rectifiers can be installed in a much closer proximity to the tanks. The reduced installation expenses, coupled with the lower process voltage, are additional advantages provided by oil-cooling. To reduce the size of the rectifier, corrugated tanks are used as an enclosure instead of a barrel design. For extremely compact designs, oil can be cooled by means of an oil/water heat exchanger using forced-oil circulation. The heat losses are then removed from the proximity without affecting the plating shop’s ambient temperature. As with traditional air-cooled rectifiers, oil-cooled rectifiers can be controlled by SCR’s. Additionally, it is also possible to use a variable ratio transformer control. This control system offers a constant low DC ripple of only 5% from 0 – 100 % output power, unlike SCR systems with a variable ripple of  5%– 60% under normal operating conditions. Oil cooled rectifiers are commercially useful alternatives for plating applications in the range from 1000 A  up to almost 15000 A.

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