MEWOI-VLF Series 0.1Hz VLF Hipot Testers
MEWOI very low frequency (0.1Hz to 0.01Hz) withstand testers, 30kV to 90kV peak, for cables and large rotating machines, with touch screen, waveform display and printed reports.
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Overview
A power-frequency withstand test on a long cable or a large generator needs a very large test set, because the cable's capacitance draws a lot of charging current at 50Hz. Testing at 0.1Hz reduces that charging current by a factor of about 500, so a compact, portable VLF tester can apply an equivalent AC withstand test. VLF testing is also less damaging to insulation than DC withstand testing.
The MEWOI-VLF series automates the whole test under microcomputer control, including raising and lowering the voltage, measurement and protection. A capacitive touch screen shows the output waveform, and test reports can be printed. Four ratings cover cables and motors up to the 35kV class, with automatic frequency reduction from 0.1Hz to 0.01Hz for larger capacitive loads.
Key Specifications
| Rating | Output (peak) | Max load capacitance | Frequency | Suits |
|---|---|---|---|---|
| 30kV / 1.1µF | 30kV | ≤10µF | 0.1–0.01Hz auto | Cables and motors ≤11kV; controller 4kg, booster 25kg |
| 60kV / 1.1µF | 60kV | ≤8µF | 0.1–0.01Hz auto | Medium-voltage cables and machines |
| 80kV / 0.5µF | 80kV | ≤5µF | 0.1–0.01Hz auto | Cables and motors ≤35kV; two 40kV boosters |
| 90kV / 0.5µF | 90kV | ≤5µF | 0.1–0.01Hz auto | Cables and motors to 35kV class |
Features
- 0.1Hz VLF withstand test, equivalent to power-frequency testing
- Automatic frequency reduction to 0.01Hz for high-capacitance loads
- Fully automatic ramp, hold, measurement and protection
- Capacitive touch screen with waveform display
- Printed test reports
- Compact controller and booster for field use
Applications
Withstand testing of XLPE and other MV cables after installation or repair; generator and large motor stator testing; switchgear and cable termination testing.