what are the acceptable values for VLF testing

VLF (Very Low Frequency) testing is commonly used for the high-voltage testing of cables, transformers, and other electrical equipment. The acceptable values for VLF testing can vary depending on the specific standards and guidelines being followed. Here are some general guidelines for acceptable VLF testing values:

General Guidelines:

1. Test Voltage Levels:

• 15 kV-rated cables: 18 kV peak (12.7 kV RMS)
• 25 kV-rated cables: 36 kV peak (25.4 kV RMS)
• 35 kV-rated cables: 44 kV peak (31 kV RMS)

2. Test Duration:

• Commonly, VLF tests are conducted for 15 to 60 minutes. The specific duration can vary based on the equipment manufacturer’s recommendations and the test standard being followed.

3. Frequency:

• The testing frequency for VLF is typically 0.1 Hz, but it can range from 0.01 Hz to 0.1 Hz.

Standards and References:

1. IEEE 400.2-2013:

• This standard provides guidance on the testing of shielded power cable systems using VLF techniques. It specifies different test voltages and durations depending on the cable rating and condition.

2. IEC 60502-2:

• This standard covers the power cables with extruded insulation and their accessories for rated voltages from 1 kV to 30 kV. It includes guidelines for VLF testing.

3. Manufacturer Recommendations:

• Always refer to the specific equipment manufacturer’s guidelines for VLF testing. Different manufacturers might have varying acceptable values and test procedures.

Example Values from IEEE 400.2-2013:

• 15 kV Cable: Test at 18 kV peak for 30 minutes.
• 25 kV Cable: Test at 36 kV peak for 30 minutes.
• 35 kV Cable: Test at 44 kV peak for 30 minutes.

Precautions:

• Safety: Ensure all safety protocols are followed to prevent accidents.
• Calibration: Properly calibrate the VLF tester to ensure accurate voltage levels.
• Condition of Equipment: Inspect the equipment before testing to avoid further damage if the equipment is already compromised.

These sources provide comprehensive details about VLF testing standards, procedures, and acceptable values for various types of electrical equipment. Always ensure to follow the latest standards and manufacturer guidelines for accurate and safe testing.

Jul 31,2024