CTRL Systems, Inc. - Sound Solutions

CTRL Systems, Inc.

Technical Bulletin

No.00-001

Quality Control

Electrical



	Manufacturing



	Transformer, miniature [Used in doorbells, power supply, PLC actuators etc.]



	Arcing in the windings or at the insulation causes failure of these small transformers. In the construction of these transformers, wire that has been coated with shellac is wound in layers and separated by an insulating material. The shellac serves as insulation between the wire and different material is used to insulate the assembly [paper, Teflon, or rubber] if the shellac has been damaged in assembly or the insulation has been mis-aligned arcing and failure will occur.



	The customer uses a sampling test that supplies power 2 to 3 times the rated load for each model transformer. This overload would breakdown the windings and eat through the insulation leaving a telltale soot mark. If the marking was not obvious or the insulation was a dark color then the testing would need to be done in the dark, so that the minute arcing could be observed. This test proved to be unreliable and costly. We were able to identify the failures at, or slightly above, the rated amperage eliminating the unnecessary destruction of components. A quick scan at full gain and low potentiometer settings revealed the faults.

Labor costs and operating expense were lowered significantly. The reliability of the shipped products was enhanced. Quality Assurance program was able to identify and correct assembly problems on the line.

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