VLF-90
The VLF-90 is a 90 kV peak sinusoidal VLF hipot test set that brings the family's highest rating…
- Maximum output voltage 0 – 90
- Output current 0 – 30
- Output frequencies 0.1 / 0.05 / 0.02 / 0.01
VLF-40
40 kV Very Low Frequency (VLF) AC Cable Test Set
40 kV peak split-system VLF hipot that proves the dielectric strength of installed power cable with a non-damaging AC stress.
Maximum output voltage
0 – 40
Output current
0 – 30
Output frequencies
0.1 / 0.05 / 0.02 / 0.01
Load rating at 0.01 Hz
≤ 5.5
Measurement accuracy
± 3 % of reading
Controller + HV tank
4 + 40
Overview
Technical Specifications
| Specification | Value | Unit |
|---|---|---|
| Output AC voltage (peak, sinusoidal) | 0 – 40 | kV |
| Output current (peak) | 0 – 30 | mA |
| Output frequency | 0.1 / 0.05 / 0.02 / 0.01 | Hz sinusoidal |
| Duty cycle | Continuous | |
| @ 0.1 Hz | ≤ 0.5 | µF |
| @ 0.05 Hz | ≤ 1.1 | µF |
| @ 0.02 Hz | ≤ 2.2 | µF |
| @ 0.01 Hz | ≤ 5.5 | µF |
| Measurement accuracy | ± 3 % of reading | |
| Voltage positive / negative peak error | ≤ 3 % | |
| Controller unit weight | 4 | kg |
| High-voltage tank (booster) weight | 40 | kg |
| Design | Two-piece split system (controller + HV tank) | |
| Power supply | AC 220 V / AC 230 V, 50/60 Hz, or AC 120 V, 60 Hz | |
| Operating temperature | −10 … +50 | °C |
| Storage temperature | −20 … +70 | °C |
| Humidity | ≤ 85 % RH | |
Key Features
Dielectric strength verification
Raises installed cable to a defined VLF AC level so weak joints and ageing insulation fail during the controlled test rather than in service.
Non-damaging AC test waveform
Sinusoidal polarity-reversing output stresses polymer insulation like operating AC without DC space-charge effects.
40 kV peak at 30 mA continuous
Full rated voltage across a load rating up to 5.5 µF at 0.01 Hz on a continuous duty cycle.
Four output frequencies
0.1 / 0.05 / 0.02 / 0.01 Hz to match charging-current demand to long feeders and heavy cable sections.
Split two-piece system
4 kg controller and 40 kg high-voltage tank for truck or van transport to MV sites.
Automatic pass/fail with on-site printout
7-inch touch screen interprets results to IEEE 400.2-2013, stores them internally and prints via the thermal printer.
PC-free operation
Setup, execution and documentation handled entirely from the controller.
Applications
Distribution cable withstand testing
Proof testing power cable insulation to verify dielectric strength.
Post-installation & post-repair checks
Acceptance checks on medium-voltage cable circuits after installation or repair.
Maintenance testing
Exposing ageing insulation and defective joints before they fail in service.
Contractor handover testing
MV network cable handover verification by installation contractors.
Utility reliability programs
Periodic proof testing as part of industrial and utility cable maintenance.
Frequently Asked Questions
What does proving dielectric strength mean for a power cable?
The cable is raised to a specified VLF AC voltage for a defined time. If the insulation withstands without breakdown, its dielectric strength is confirmed at that test level; if a weak spot exists it is expected to break down during the controlled test so it can be located and repaired.
Does VLF testing damage healthy cable insulation?
No. The VLF waveform is a genuine alternating voltage with half-cycle polarity reversal, stressing the insulation like operating AC without depositing space charge. A cable that passes is not weakened by the test.
How does the VLF-40 handle long or high-capacitance circuits?
Charging current falls as frequency drops. By selecting 0.05, 0.02 or 0.01 Hz, the operator reduces current demand and can test circuits up to 5.5 µF at 0.01 Hz — far beyond the reach of a 50/60 Hz source of the same size.
Is a PC required to run the VLF-40?
No. Test setup, execution, automatic IEEE 400.2-2013 pass/fail interpretation and printing are all handled from the 7-inch touch screen and the built-in thermal printer.
Downloads
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