installation, operation and maintenance guide - Hammond Power ...

Page 16 shifted insulation due to shipping orhandling.It is emphasized that low megger readings - anindication of low insulation levels between the coreand ground- are not of concern unless there arethrough bolts. The core is intended to be grounded inany event.(12) Coil DistortionShort circuited coils exhibit severe distortion from theirnormal round or symmetrical appearance.(13) High Conductor LossOverloads, or terminal boards not on the identical tapposition can result in conductor heating.(14) Breakers/Fuses OpeningBreakers and fuses opening can be caused by: overload conditions voltage or current harmonics short circuit insulation failure that causes excessivecurrent. voltage too high when energized setting too low to allow for inrush currentshould be directed through the windings. This shouldcontinue for 24 hours or until after the evidence ofcondensation is no longer visible.Transformers that have been exposed to floodconditions, direct rain or sprinklers, may not be ableto be dried out appropriately. Consult the factory forfurther instructions.If any of the above conditions are evident, thetransformer should be immediately removed fromservice. Corrective measure should be undertaken inconsultation with the manufacturer representatives orqualified personnel.After an evaluation has been completed, thetransformer may be reenergized after the appropriatereworking, or the unit may have to be returned to thefactory for further evaluation or repair.(15) Excessive Cable HeatingCauses include: improperly bolted or crimped connections loose connectors loose lead wires or terminals incorrectly sized cables or terminals overload condition(16) MoistureIf a transformer has been exposed to moisture such ascondensation or rain, the unit should be dried out priorto energization. (refer to Dry-Out section on page 7)Hot or warmed air, radiant heat or internal heat