SP-02-74 test voltage formula
Test Voltage = 1250 x √
T
Where T
coating
is the coating thickness in mils (0.001”).
Alternatively
Test Voltage = 250 x √
T
Where T
coating
is the coating thickness in microns (0.001mm).
After the test voltage is calculated it is necessary to check that the voltage
is not so high as to damage the material. The dielectric
strength is
the
voltage at which the material starts to breakdown, this is expressed in volts
per mm, normally with D.C. As an example, a 2mm thick sheet of P.V.C.
would require a voltage of 11.18kV using the above formula.
Referring to the manufacturer’s technical data, the dielectric strength is
8.4kV per mm. Therefore, 2mm of such material has a dielectric strength
of 16.8kV and is safe to test at 11.18kV.
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