Rotating Machines

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.



Winding Coating deterioration
Visual inspection: interface semi-conducting and gradient coating (coating deterioration)
Visual inspection: end windings
Visible camera: location of PD on end winding
Corona PD on interface semi conducting and gradient coating
UV inspection: Corona PD on interface semi conducting and gradient coating
UV camera - Pd on end windings
UV inspection, PD on end windings

Ofil’s corona cameras pinpoint and display corona partial discharge and reveals the emitting sources, and thereby reduces investigation time and labor costs, and assist perform the reactive maintenance that is needed for the reliable ongoing operation of motor/generators/switchgear. r