jännitteenkeston

Jännitteenkesto, or voltage withstand, is the ability of an electrical component, insulation, or system to endure a defined electrical voltage for a specified period without breakdown, flashover, or excessive leakage current. It is a key property in insulation coordination and safety assessment, helping to determine suitable insulation levels and safety margins for devices operating under normal and transient conditions.

Measurement of jännitteenkesto is typically carried out with a dielectric withstand test (often referred to as a hipot test). A higher-than-operating voltage, applied as either alternating current (AC) or direct current (DC), is maintained for a defined duration. Acceptance criteria usually require that no insulation breakdown or sustained excessive leakage current occurs and that surface flashovers or other failures do not compromise operation. The test setup includes protective measures to ensure safety and to prevent damage to the sample or tester.

Several factors influence jännitteenkesto, including the dielectric strength of the insulation material, its thickness, geometry, and surface condition. Environmental conditions such as humidity, temperature, and pollution, as well as aging and mechanical stress, can reduce withstand capabilities. Materials with higher dielectric strength and properly designed insulation geometries generally exhibit greater jännitteenkesto.

In practice, jännitteenkesto informs design choices and standards compliance for electrical equipment such as transformers, cables, insulators, and printed circuit boards. It is closely related to related concepts like creepage and clearance distances, insulation coordination, and harmonic or transient overvoltages. Standards organizations (for example IEC and other national bodies) provide terminology and test procedures to ensure consistent assessment of voltage withstand across different applications.