Program Overview
Extruded-dielectric cables rarely fail on the day they are installed. They fail months later, at a joint with a misplaced stress cone or a termination contaminated during installation. Very low frequency (VLF) AC withstand testing is the field method that exposes these defects before energization, without the space-charge damage that DC hipot testing can inflict on aged XLPE insulation.
This program builds practical competence in VLF testing at 0.01 to 0.1 Hz using sinusoidal and cosine-rectangular waveforms. Participants learn how to select test voltages and durations from IEEE 400.2, prepare cable circuits and terminations for test, control the test zone, and read leakage current and voltage behavior during the hold period. The course closes with diagnostic extensions, including tan delta and partial discharge monitored withstand, and a structured approach to pass/fail decisions and test reporting.
Learning Outcomes
- Explain the physics of VLF withstand testing and why it replaces DC hipot testing for extruded cable insulation
- Select test voltage, frequency and duration for installation, acceptance and maintenance tests in line with IEEE 400.2
- Prepare cable circuits, terminations and surge arresters for safe isolation and testing
- Set up, operate and discharge a VLF test set using a documented safe system of work
- Interpret withstand results, leakage trends and flashover events to reach a defensible acceptance decision
- Produce a complete test record that supports commissioning and asset-management decisions
Program Modules
- Introduction to VLF Testing Principles — capacitive charging, why low frequency reduces test-set size, and how VLF compares with DC, 60 Hz and damped AC methods
- Types and Functions of VLF Testers — sinusoidal and cosine-rectangular waveforms, load capacity versus cable length, and integrated tan delta and partial discharge options
- Test Planning and Safety — isolation, earthing, exclusion zones, test-area barriers and the OSHA requirements that govern HV testing work
- Performing VLF Hipot Testing — connection, voltage ramping, hold periods, monitoring during the test and safe discharge and grounding afterwards
- Analyzing Test Results and Acceptance Criteria — interpreting withstand outcomes, recognizing termination flashover versus insulation failure, and applying IEEE 400.2 criteria
- Practical Session with an HV Hipot Test Set — hands-on testing of cable samples with deliberate defects, from setup through reporting
Who Should Attend
- Cable testing and commissioning technicians
- Electrical engineers responsible for MV and HV cable acceptance
- Cable jointers who want to understand how their work is tested
- Utility and industrial maintenance supervisors
- Third-party inspection and QA/QC personnel
Standards & Codes Referenced
- IEEE 400.2
- IEEE 400
- IEC 60502-2
- IEEE 433
- OSHA 29 CFR 1910 Subpart S
Assessment & Certification
Assessment combines a written examination on VLF theory, test parameters and IEEE 400.2 acceptance criteria with a practical assessment in which each participant sets up a VLF test set on a cable sample, completes a withstand test with correct isolation and discharge, and interprets the result. Practical sessions take place at ASEEE-approved training centers, using calibrated equipment and realistic work scenarios under the supervision of a qualified assessor.
Participants who meet the competency criteria receive an ASEEE competency certificate carrying a unique certificate ID that employers and clients can verify online through Certificate Check. ASEEE recommends recertification every 3 years to keep skills aligned with current practice and revised standards.
