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VLF Withstand Testing for MV and HV Cables

Our VLF withstand testing solutions help you verify the condition of MV and HV cables quickly and reliably. From commissioning to diagnostics, Megger gives you the tools to prevent failures, reduce downtime, and keep your network running safely.

Unreliable cable networks lead to unplanned outages, costly downtime, and reputational risk. VLF withstand testing helps you catch insulation issues before they become failures — giving you the confidence to make data-driven maintenance decisions.

Megger’s VLF solutions support both MV and HV applications and go far beyond simple pass/fail testing. With integrated diagnostics like Tan Delta, partial discharge, and sheath testing, you can pinpoint degradation, verify repairs, and fully commission new installations.

Every product is built for efficient field use, combining portable design with modern automation to speed up workflows and reduce manual error.

Frequently Asked Questions

Your choice depends on the maximum test voltage and the cable length or insulation level.

  • VLF Sine 37 kV – ideal for typical MV distribution cables and short cable runs
  • VLF Sine 45 kV – better for longer runs and higher loads
  • VLF Sine 62 kV – designed for higher insulation levels or testing multiple phases at once

All models deliver the same core test capabilities. Not sure which one fits your network? Contact us for tailored advice.

All VLF Sine and VLF CR models use MeggerBook Lite — a free, purpose-built tool for storing, analysing, and reporting test data.

It allows you to:

  • Archive results
  • Compare historical trends
  • Generate standardised reports

Export is quick and paperless via USB or wireless (depending on model). No third-party tools or PCs required in the field.

Megger’s VLF systems support a wide range of cable testing needs, including:

  • Commissioning of new installations
  • Condition assessment of ageing cables
  • Sheath integrity testing and fault pinpointing
  • Tan Delta and offline partial discharge diagnostics (with optional coupler)

They’re ideal for utilities, renewables, and industrial sites — anywhere cable reliability matters.

Yes — all VLF Sine models can perform offline partial discharge (PD) testing when used with the PDS 62-SIN coupler.

This enables you to detect insulation defects before failure, giving you deeper diagnostic insight beyond standard withstand tests. It's a powerful tool for teams focused on proactive asset management.

Talk to an expert about VLF testing

Need help choosing the right VLF test set? Want to see how our solutions work in the field? Our team is here to help.

We’ll guide you through the best options for your application, arrange a live product demo, or provide a tailored quote. 

Whether you're upgrading existing equipment or planning a new commissioning project, we’ll help you get the job done with confidence.

Additional resources

Take a deeper dive into our portfolio of VLF products

Blog: an introduction to VLF cable testing

An overview of this key method in cable testing and diagnostics

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Case study: Cable condition assessment

How Megger’s VLF products localised a critical defect in a utility’s network.

Read more

Guide: VLF testing on motors and generators

Our guide to another key application for VLF testing

Read more