Voltage Proof Test
This test (often called the dielectric voltage withstand) determines the dielectric integrity of the cable insulation. Dielectric integrity is determined by placing the wire/cable in a water bath. An AC voltage potential is applied across the insulation between a wire/cable conductor and the ground. This test is typically run as part of posttest assessment procedures to evaluate the sample's insulation/jacket integrity after an environmental or other type of test.
The benefits of performing this test include:
- Determine if there are any imperfections in the sample insulation/jacket and the voltage at which there was insulation breakdown.
- Identify if the sample can withstand the specified voltage.
- Provide information to support a voltage rating (a common method for defining voltage rating is to divide the dielectric voltage withstand test value by two, then subtract 500 (e.g. (0.5 * 2.5kV) - 500V = 750V, where 2.5kV is the dielectric voltage withstand test value).
Lectromec currently has the capability to test up to 15.0kVAC.
Procedure
- Perform visual examination of wire and record defects.
- Strip the ends of the sample.
- Coil sample and place in the water bath with ends above the water line.
- Wait the specified duration.
- Connect sample to high voltage test system and place electrode in the bath.
- Apply power and slowly raise voltage to specified voltage.
- Wait the specified duration.
- If insulation breakdown occurs, record maximum achieved voltage. If no failure, then record leakage current.
- Slowly lower applied voltage.
- Report results.
Covered specifications
- EN3475 Method 302
- NEMA 27500 Method 4.3.7
- ASTM D3032 Method 8
- AS4373 Method 510
- EN2591 Method 207