Choosing The Right Rectifier…continued

Cooling - All rectifiers generate heat, much like the engine in a car, and that heat must be removed for the rectifier to operate properly.  The two rectifier cooling choices are air or oil: 

• Air-cooled rectifiers are the most common and utilize convection to cool the internal components of the rectifier.  Vents installed low in the cabinet draw cool air inside while heated air escapes thought vents higher in the cabinet.
• Oil cooled rectifiers are typically used in environments where air-cooling is not practical. This would include locations where salt air or dust can damage internal components or where an ignition source, such as a faulty electrical connection, could be an explosive hazard.  As heat is generated, the oil inside the cabinet circulates and transfers the heat to the cabinet walls where cooling fins disperse the heat into the atmosphere.

Style - Most manufacturers offer different rectifier "styles" for a variety of uses.  These can include standard models, lower cost alternatives, specialty use rectifiers, and more. Rectifiers styles vary from manufacturer to manufacturer. The style you choose will depend on your application.

Cabinet Choices - Besides the air and oil cabinets mentioned, there are other cabinet choices to consider.  In addition to the materials and finishes, listed below, options include multiple doors, pole and pad mounting options, decorative styles and more.

• Air cooled rectifiers
  • Hot dipped galvanized steel (most common).
  • Powder coated steel.  White is standard but many colors are available.
  • Anodized aluminum, with or without a clear coat.
  • Stainless steel.
  • Oil cooled rectifiers
    • Hot dipped galvanized steel (most common).
    • Stainless steel (very costly).

Options - As with buying a car, there are many available options to choose from when selecting a rectifier.  Some are recommended where others are purely the option of the end user. These options include, but are not limited to:

• AC & DC arrestors, which are recommended to protect the rectifier from electrical surges, such as lightning or other electrical "events".
• Filter chokes (aka efficiency filters), which are recommended for single phase powered rectifiers, help reduce DC ripple and energy costs.
• Base mounts to convert a "pole mount" cabinet into a freestanding cabinet.
• Power-on indicators.  Through the use of an external light, users can determine if power is being supplied to the rectifier unit.
• DC failure lights provide an external indication that DC output current has been reduced or interrupted.
• DC circuit breakers are sometimes recommended to provide additional protection on the DC side of the rectifier circuit.
• "Convenience" outlets are provided inside a rectifier and used to power 115-volt equipment, such as a drill motor or similar.
• Multiple unit cabinets.  This is rare but used when a number of separate rectifiers are needed in a single cabinet.
•  Multiple DC output terminals to protect more than one structure.
• Terminal strips for wiring external remote monitoring equipment.
• And many more.

Rectifiers have been used for decades and are built to last for at least twenty years.  Therefore, it's important to make the correct rectifier selections when you order a rectifier, as you will live with those choices for many years to come.  If you need assistance with ordering a rectifier, please contact a Farwest Corrosion Control representative for assistance.