■ electrical diagnostic testing to characterize the insulation
system, including tangent delta [also called
dissipation factor or power factor (PF)], delta tangent
delta [or PF tip-up (PFTU)], and partial discharge
analysis (PDA )
■ short-term electrical withstand or destructive tests,
including insulation resistance (IR) and polarization
index (PI; IR-PI), ac or dc high-potential (hipot) tests,
and short-rise-time tests of the main and turn insulation
■ long-term aging tests that may require exposure to elevated
temperature, mechanical stress, electrical stress,
or a combination thereof. These stresses may be applied
as a constant stress or by controlled cycling.