GENERATOR INSULATION TEST REPORT AND REPAIR
Measurements performed with INSULATION MULTIMETER at 1000V
( ∞ = 2.2GΩ ).
Electrical insulation degrades over a period of time. Abnormal stresses can bring about an increase in this natural aging process that can severely shorten the working life of the insulation. For this reason perform regular testing to identify whether increased aging is taking place and, if possible, to identify whether the effects may be reversible or not.
What Causes insulation to Degrade.
There are five basic causes for insulation degradation. They interact with each other and cause a gradual spiral of decline in insulation quality.
Insulation is designed for a particular application. Overvoltage and undervoltage cause abnormal stresses within the insulation, which can lead to cracking or delamination of the insulation.
Mechanical damage such as hitting a cable while digging a trench is fairly obvious but mechanical stresses also may occur from running a machine out of balance or frequent stops and starts. The resulting vibration from machine operation may cause defects within the insulation.
While you would expect insulation to be affected by corrosive vapors, dirt and oil can also operate to reduce the effectiveness of insulation.
Running a piece of machinery in excessively hot or cold conditions will cause over expansion or contraction of the insulation which might result in cracks and failures. however, thermal stresses are also incurred every time a machine is started or stopped. Unless the machinery is designed for intermittent use, every stop and start will adverselly affect the aging process of the insulation.
Environmental contamination covers a multitude of agents ranging from moisture from processes, to humidity on a muggy day, and even to attack by rodents that gnaw their way into the insulation.
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