DC withstand voltage is strictly prohibited: For cross-linked polyethylene (XLPE) cables, DC withstand voltage testing is strictly prohibited; ultra-low frequency (0.1Hz) or power frequency resonant AC withstand voltage must be used.
Wiring inspection:
The high-voltage output wire must be suspended in the air and must not drag on the ground or contact other objects.
The grounding wire must be reliably connected, first connecting the grounding end, then the high-voltage end.
Discharge operation:
Before and after the test, a dedicated discharge rod must be used to fully discharge the cable under test (first discharge through a resistor, then directly ground).
Although the ultra-low frequency high voltage has a low frequency, its energy is sufficient to cause fatal injury to humans; do not be careless.
Environmental requirements:
Avoid outdoor testing in thunderstorms, heavy fog, or relative humidity >85%.
If the surface of the cable terminal head is dirty or damp, wipe it clean or install a shielding ring to prevent misjudgment due to surface flashover.
Test standards:
If the surface of the cable terminal head is dirty or damp, wipe it clean or install a shielding ring to prevent misjudgment due to surface flashover.
Test standards:
Strictly implement DL/T 849.4-2019 "General Technical Specifications for Special Testing Instruments for Power Equipment - Part 4: Ultra-Low Frequency High Voltage Generators" and GB 50150 "Standard for Acceptance Tests of Electrical Equipment in Electrical Installation Engineering".
Typical test voltage: For newly commissioned 10kV XLPE cables, it is usually
(approximately 17.4kV-21kV) with voltage applied for 15-60 minutes; for 35kV cables, it is usually
6. Typical application scenarios
Acceptance test for new cables: After installation, verify the installation quality and eliminate insulation damage during transportation or construction.
Preventive testing: Regular health checks (e.g., every 3-6 years) for cables in operation.
Verification after fault repair: After repairing cable intermediate joints or terminal heads, verify the repair effect.
Condition assessment: Combined with tanδ measurement, assess the remaining life of aged cables and guide replacement plans.
Summary and recommendations:
For most power supply bureaus, engineering companies, and maintenance teams, the 0.1Hz ultra-low frequency high voltage generator (with optional tanδ function) from Wuhan UHV Electric or domestic professional brands of the same level is the best choice. They not only fully comply with the latest national standards but also far surpass imported equipment in portability, ease of operation, and cost-effectiveness. If you need in-depth cable condition assessment (such as precise location of aging points), you may consider adding a partial discharge detection module or choosing a flagship model with advanced diagnostic functions.
