High Voltage, or Fluctuating Voltage Condition


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Think and act in a safe manner. Always disconnect power and use a lockout before you work on the E-coat system, or any of the related subsystems. Observe any confined space conditions. Use the appropriate safety equipment and clothing for the task. Please carefully read all the instructions listed below to familiarize yourself with the project before attempting to perform any of the work.

Required Materials

  • Flashlight


High voltage is a problem condition that exists either for a very short period of time or possibly longer. There are E-coat systems that operate at lower voltages; however, others may require more voltage even though they carry the same load and paint characteristics. The voltage readout can even vary without any direct change by the operator.

This reference addresses sudden high voltage conditions or fluctuating voltage. Voltage that has increased gradually over months/years requires a different approach - See #11.

Intermittent voltage changes

  1. Check to make sure the DC rectifier is not set to operate a ‘constant current’, where the voltage is increased up or down in order to keep the current at a constant level.
  2. Does the DC rectifier have a current limiter? If so is the voltage being reduced in order to limit current?
  3. Is sufficient AC current being delivered to the DC rectifier from the sub station?
  4. Is it time to perform a PM on the DC rectifier control system?
  5. Verify the voltage meters are functioning properly.
  6. Is there an electrical component that is heating up unusually, which may cause a poor connection? When it is allowed to cool down the connection is restored and the voltage can be lowered.

High voltage condition

  1. Check all items shown above.
  2. Look at cabling between DC rectifier and the bus bar system inside the E-coat enclosure. Are there loose joints? Look for signs of heat stress. Remember electrical components heat up as parts go through the E-coat system and cool off during line strips when no parts are being painted.
  3. Look at the connections between the bus bar system and the Anode Cells and Bare Electrodes. Are the joints tight and free of corrosion?
  4. Make sure the Anode Cells are full of anolyte fluid at all times. If the Cells are only half full, there should be a pronounced E-coat film build on the bottom side of the ware. Is there evidence of biological growth in the anolyte?
  5. Consider the following E-coat paint parameters; conductivity (is less than before), temperature (is less than before), % solids (is less than before), and wet film resistivity (is more than before). #Generally, if there has been a significant change in one of these parameters, then the voltage will probably remain high until the condition that caused the parameter to change is gone from the E-coat bath.
  6. Is there a change in the zinc phosphate crystal (usually more) growth that results in less surface conductivity?
  7. Is there a change in the surface conductivity of the metal substrate?
  8. Are the ware hangers dirty, or do they have poor electrical contacts?
  9. How do the ware hangers contact the grounding shoes? Is there sufficient contact force?
  10. Check the cabling between the grounding bus bar and the DC rectifier.
  11. If all of the above checks out okay, how old are the anode cells? Are the anodes in good shape? How old are the membrane shells? If more than 4-5 years old, it’s time to change them. See Service Reference #990157 Membrane Shell Replacement Strategy.






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