Connect the VLF high-voltage output line to the cable core, and ensure the grounding wire is reliably grounded.
U 0 is the voltage of the cable conductor to ground. If a cosine square wave is used, the voltage value usually refers to the peak value; if a sine wave is used, it refers to the peak value (2 × 2 × RMS value). 6. Brief Operation Procedure Disconnection and Isolation: Disconnect both ends of the cable under test from equipment such as switchgear and transformers to ensure isolation. Discharge and Grounding: Fully discharge and hang grounding wires to ensure safety. Wiring: Connect the VLF high-voltage output line to the cable core, and ensure the grounding wire is reliably grounded. If partial discharge testing is performed, install coupling sensors. Parameter Setting: Select waveform (sine/cosine), target voltage, and pressurization time. Automatic Voltage Ramp-Up: The device automatically ramps up the voltage at a slow rate (e.g., 1-2 kV/s) to the target value. Withstand Voltage Hold: Maintain the target voltage for the specified time. If breakdown occurs during this period, the device automatically trips and records; if partial discharge testing is performed, record the PD pattern throughout. Automatic Voltage Reduction and Discharge: After the test, the device automatically reduces the voltage to zero and activates the internal discharge resistor to discharge the cable. Note: After VLF testing, residual charge on the cable is released slowly; ensure discharge is complete before disconnecting! 7. Key Selection Indicators (2026 Edition) Table Indicator Recommended Requirement Description Output Voltage Cover the cable level under test (e.g., 0-40kV, 0-80kV) Must meet 3
