- The stress distribution for transformers, motors, and generator winding is different for ac voltage
- The residual charge after a dc voltage test must be carefully discharged.
- The time required to conduct a dc high-potential test is longer than for an ac high-potentail test.
- Literature governing dc testing of cables suggest possible ill effects dc testing may have on some cables.
- Defects, undetectable with dc, can cause failure under ac.
- The voltage may not stress uniformly the insulation system.
- Temperature and voltage dependence of resistivity.
- Space charge formation-future potential failures