The dielectric strength test or high potential or hypot test is performed to determine the efficiency of insulation in an electrical device or equipment. This electrical test on a component or product serves to measure the device's ability to operate safely in electrical conditions.

Dielectric strength is a measure of the electrical strength of a material as an insulator. Dielectric strength is the maximum voltage required for the material to show a dielectric failure. The higher the dielectric strength of a material, the better its quality as an insulator.

There are three main methods used to determine the dielectric strength of an insulator: the short time method, the slow rise rate method, and the step-by-step method. In all three, the test sample is placed between two electrodes in air or oil. The most commonly used test method is the short-time method. Voltage is applied to the two electrodes and the voltage is increased from zero to the dielectric distortion limit.

The break point is the point at which the test specimen is burned or punctured. The voltage increase rate is determined by the time it takes for the test sample to reach dielectric deterioration.

An important electrical feature of the insulators is their dielectric power. The dielectric strength depends on the type and shape of the plastics and electrodes and the environment surrounding the insulator.

Briefly, dielectric strength refers to the highest electric field in which an insulating material can withstand ideal conditions without deterioration.

The dielectric strength tests performed by the competent authorities are as follows:

• TS EN 50289-1-3 Communication cables - For test methods - Specifications - Part 1-3: Electrical test methods - Dielectric strength

• TS EN 50289-3-17 ... Section 3-17: Mechanical test methods - Dielectric adhesion and sheath

• ASTM D149-09 Standard test method for dielectric degradation voltage and dielectric strength of solid electrical insulation materials at commercial power frequencies