Urban distribution networks in Vietnam and Indonesia are converting overhead feeders to underground cable at a fast pace. A new cable installed through congested streets, in high groundwater areas and in tropical heat carries the risk of installation defects – damage during pulling, incorrect bending, and the single most common source of early failure: poor jointing and termination work. Acceptance testing before energisation finds these defects while the cable is still easy to repair.
Why acceptance testing matters for new cables
Installation stress in the tropics
High ambient temperature, humidity and groundwater create conditions where a marginally damaged cable can fail early. Proving the cable before it enters service is cheaper by orders of magnitude than locating and repairing a buried fault later.
Joint and termination quality
Most early cable failures start at joints and terminations made during installation. Acceptance testing that includes these points identifies workmanship defects while the jointing crew is still on site.
Oscillating wave testing for acceptance
An oscillating wave test (OWTS) applies a damped AC voltage close to the cable’s operating stress and measures partial discharge (PD) activity along the cable. For acceptance of new installations it provides:
- PD localisation – locating defects to a section or joint position, so repairs are targeted
- Pass/fail evidence – a measured record that the cable meets the specified PD acceptance level before energisation
- Baseline for the future – the first PD map of the cable becomes the reference for later condition assessment
Applying OWTS in Vietnam and Indonesia
When to test
- After jointing and before energisation for new circuits
- After major repair or re-jointing of existing circuits
- Before taking over contractor-installed cable from the installer
Testing in the field
Portable OWTS units connect to the cable end through the switchgear or a test termination. The test is performed with the cable isolated, per the utility’s switching procedure. Duration is short enough to fit commissioning schedules.
Working with contractors
Specify the acceptance PD limit in the contract and define the test procedure, so the installer knows the standard before work begins. A witnessed acceptance test gives the utility a defensible handover record.
Beyond acceptance: building the cable record
Store the acceptance PD map for each circuit. Later, if the cable is re-tested after years of service, comparing maps shows whether new activity has appeared – turning acceptance testing into the foundation of a condition-based cable maintenance programme.
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) manufactures oscillating wave test sets and cable PD diagnosis systems used for acceptance testing and condition assessment of medium-voltage cables, and supports utilities, EPC contractors and testing companies in Vietnam, Indonesia and across Southeast Asia with OEM/ODM supply and application guidance. Contact the HUWOR sales team for specifications.