The Dielectric Loss Analysis DLA unit is an off line test used to determine both the dielectric loss energy and the loss tangent (Tan Delta) of a machine at voltage steps up to line voltage.
Dielectric Loss Analysis DLA and Tan Delta testing are well established test and have been used for many years to evaluate the condition of machine insulation systems
Both dielectric loss energy and loss tangent are affected by the void content of the insulation, the higher the void content the higher the loss tangent and dielectric loss. The loss tangent represents the sum of solid material (conductive type) losses and the gaseous losses as the voids within the insulation discharge causing breakdown and ionisation. The dielectric loss energy is representative of the gaseous discharge losses within the voids and can also be affected by other external sparking type discharges. The results can also be affected by contamination, damp, corona shield and stress grading problems.
- The main cell wall insulation of all coils above 4.0v AC are tan delta tested using an inductively coupled capacitive bridge to measure tan delta (power loss through the insulation) at 0.2v voltage steps up to the voltage.
- All formed coils manufactured at voltages of 6000 volts and above will be subjected to a tan delta test in accordance to ESI 44-5, as will all completed machines of these voltages.