Automotive Assembly Division
Chicago Assembly Plant

Inter Office

To:       F. S. Boggess; R. E. Stevensen

cc:       R. Gilligan

Subject:          Maintenance Workshop – Surge and Transient Suppression

Transient and surge problems with voltage supply systems are common problems throughout industry. As we utilize more sophisticated and sensitive devices, these problems become greatly amplified. Some common problems associated with transients and surges are:

  •             Computer and PC problems, i. e. memory loss and erratic operation.
  •             Excessive failure rate of microprocessor based controls, i. e. welding.
  •             Reduced efficiency of motors, compressors and transformers.
  •             Decreased life of fluorescent tubes and ballasts.
  •             Increased power consumption.

In an effort to overcome these problems, we have tried many devices, all of which were ineffective and very costly, with some causing down time.

We found a device that does live up to most of its claims and appears to justify in-depth trials. The System is distributed by Midwest Electrical Consultants. Midwest arranged an in-plant trial to show us the before and after effects of the System.

The test was conducted by plant personnel with Midwest supervising hookup of the device to assure that it was properly installed. A Dranitz Recorder was used and tests were run on the Front Structure 440V 3 phase welding power supply. We recorded a 30-50 volt imbalance between phases. At that time we also documented 705 surges on phase A, 233 surges on Phase B, and 189 surges on Phase C. The duration of the surges carried from .5 seconds to 2.5 seconds at a voltage between 295 volts to 350 volts per phase. Seventeen transient (spikes greater than 100 volts over nominal) ranging from 395 volts to 800 volts for a period of 2,000 to 3,000 milliseconds.

After installing the System and monitoring the system at the same point, results as follows:

The phase imbalance was reduced to 4 – 5 volts.


  • Phase A = 0
  • Phase B = 0
  • Phase C = 0


  • Phase A = 0
  • Phase B = 1
  • Phase C = 2

The Original Letter:


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