DayCor® cameras can view, pinpoint and record corona & arcing Partial Discharge Activity (PDA) under normal lighting conditions. High voltage rotating machines experience widespread insulation problems, deterioration of coating, inadequate spacing between end windings, loose windings, deterioration of interface between semi-conductive and gradient coating.
80% of electrical motor failures start as a turn-to-turn fault, which is the weakest insulation spot in the motor. Chemical deposits that result from insulation breakdown rub the turns, when rotating, and wear the motor.
Windings are periodically being checked with corona cameras to ensure that they are corona free. Corona indicates unexpected deformation of the local electrical field caused by some kind of fault that need to be investigated. As such, UV technology can serve as a means to discover early stages of aging when corrective actions are still feasible.
UV inspection is beneficial for examining Slot exits and winding ties. Windings become loose in the slot due to combined effect of electro dynamic and thermal cycling forces due to wear
At times it becomes necessary to have access to bar/coil side in the slot after removing a few wedges. Damaged coil surfaces create discontinuities allowing voltage stresses to build up and as a result discharging PD.