Dielectric strength
The withstand voltage of an insulator before breakdown.
Definition
Dielectric strength is the maximum voltage that an insulating material can withstand without breaking down, i.e. without an electric arc passing through it. It is expressed in kV/mm for a material, or as a withstand voltage (kV) for a complete unit.
In a transformer, it guarantees the safe separation between the windings and earth, and between primary and secondary. Dielectric tests (applied voltage, induced voltage, lightning impulse) verify this withstand with a wide margin relative to the service voltage, in accordance with the standards.
Sufficient dielectric strength is the condition for electrical safety and galvanic isolation.
The ABL tip
For networks exposed to overvoltages (lightning, switching) or for safety applications, reinforced dielectric withstand is essential. ABL Transfo designs and tests its transformers to the insulation levels required by your standard.
