Silver migration may be defined as a process by which silver, when in contact with insulating materials under electrical potential, is removed ionically from its initial location, and is redeposited as metal at some other location. This process requires adsorption of water on the insulation surface. Silver is unique in this respect in that it is easily oxidized and reduced and does not passivate. Other metals do not present a practical migration hazard. Presented herein are examples of actual experience wherein silver migration caused trouble, and an explanation of this phenomenon based upon chemical and physical considerations and related laboratory evidence. It is concluded that silver should be used with great caution under the conditions noted.

The general nature of the behavior of cellulose as a dielectric in directand alternating-current fields is discussed, and some of the more important dielectric properties are tabulated. The uses of cellulosic insulation are discussed under the following five classifications: paper capacitors, high-voltage power cables, telephone cables, textiles, and reinforced and laminated insulation.The more important unsolved problems suggested by the literature and by various authorities are listed.

No abstract

No abstract

No abstract