The DC Hi-Pot test is extremely important to identify the
deterioration in the insulation as early as possible to
take corrective measures. The high potential is applied
between isolated parts of a circuit or a product, the
behaviour of electrical parameters such as Leakage
current helps identify broken or poor insulation, stray
wire strands or braided shielding, spacing problem
between terminals, tolerance errors, etc.
During the Hi-Pot test, a high voltage is applied to the
device under test (DUT) that causes a small leakage
current (microamperes) to flow from the conductor and
insulation. This small leakage current depends on three
main factors i.e.
(i) test voltage
(ii) system capacitance and
(iii) temperature of the material
The leakage current is also a combination of three
I) Conductive leakage current. Conductive current is a
small current that normally flows through insulation,
between conductors or from a conductor to ground. This
current increases as insulation deteriorates and becomes
predominant after the absorption current vanishes.
II) Capacitive charging leakage current. When two or
more conductors are run together in a raceway, these act
as a capacitor. Due to this capacitive effect, a leakage
current flows through conductor insulation.
III) Polarisation absorption leakage current. Absorption
current is caused by polarisation of molecules within the
The Hi-pot test therefore helps in making informed
decision on the safety and quality of electrical circuits
and eliminates the possibility of having a
life-threatening short-circuit or short-to-ground faults.