MFM10-1 Locate cable sheath faults quickly and accurately

Mobile sheath fault location system up to 10 kV DC

Test, prelocate and pinpoint sheath faults quickly, with bipolar accuracy and safe pulsed DC output.

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Fast, automatic pre-location

Automatically calculates distance to fault using the voltage drop method.

More reliable results with bipolar measurement

Compensates for thermoelectric and galvanic influences that can skew readings.

Pinpoint faults with the method that suits the site

Use pulsed DC for step-voltage pinpointing, or low-frequency A-frame (3 Hz / 4.8 Hz) for walking the route.

Handle difficult faults with burning mode

Up to 750 mA output current helps stabilise high-resistance sheath faults so they’re easier to locate.

Full Product Details

About the product

The MFM 10 is a battery-operated sheath fault location system designed to help you find insulation defects in cable sheaths before they develop into costly in-service failures. It supports the full workflow in one unit: sheath testing, automatic prelocation and reliable pinpointing.

How it helps you work faster and with more confidence

Test up to 10 kV DC (bipolar) to check sheath insulation on MV and HV cables, including thicker outer sheaths.
Automatic pre-location using the voltage drop method. The instrument measures voltage, current and resistance and calculates the distance to the fault within seconds.
Bipolar measurement for higher accuracy. By measuring with both polarities, the system detects and compensates for thermoelectric and galvanic influences that can distort results.
Pinpoint in the field using:
Pulsed DC output for step-voltage pinpointing with a compatible earth fault locator, and
Low-frequency A-frame method (3 Hz or 4.8 Hz) for clear directional guidance when walking the route.
Burning mode (up to 750 mA output current) to stabilise difficult faults and make them easier to locate.

Designed for on-site use

The MFM 10 uses a menu-driven interface with Megger’s EasyGo rotary encoder and a touch screen, so routine tasks are quick to set up and consistent between operators. It also includes integrated discharge with overload protection, plus connection checks to reduce the risk of incorrect hook-up.

Practical reporting

Measurements can be logged and exported via USB for reporting and traceability, supporting repeatable maintenance programmes and consistent documentation.

Product documents

Additional documentation can be found on the support tab

Data sheet

MFM-10-1_DS_EN.pdf

pdf 548.83 KB

User guide

MFM10_UG_EN.pdf

pdf 1.85 MB

User guide

MFM-M_UG_EN.pdf

pdf 1.44 MB

FAQ / Frequently Asked Questions

How is the fault distance calculated?

The MFM 10 uses the voltage drop method. It measures voltage, current and resistance before/after the fault and calculates the distance based on cable length.

Do I need an auxiliary conductor?

For prelocation, you typically need two healthy auxiliary conductors. For testing, burning or pinpointing only, simplified connections may be possible.

How does bipolar measurement improve accuracy?

By measuring with both polarities, the instrument can detect and compensate for thermoelectric and galvanic effects that would otherwise distort the voltage drop calculation.

Which pinpointing method should I use?

Use pulsed DC with a compatible earth fault locator for step-voltage pinpointing, or use the A-frame method (3 Hz / 4.8 Hz) when you want directional guidance along the route.

Is it safe to use on-site?

The system includes safety mechanisms such as interlock-controlled HV switching and integrated discharge. Always follow local HV safety rules and working practices.

Troubleshooting

Low or unstable readings that don’t match the site expectation

What it usually means: Poor connection quality, unintended earthing, or environmental influences.
What to do: Clean contact points, remove any accidental earth connections (shields/aux conductors), and repeat the test using bipolar measurement.

Prelocation distance seems inconsistent between runs

What it usually means: Thermoelectric/galvanic effects, variable contact resistance, or incorrect cable length/section data.
What to do: Run bipolar measurement, verify cable length and any multi-section parameters, and improve clamps/contact points. You can also use the burning function to stabilise the fault condition.

HV will not switch on

What it usually means: Safety interlock not satisfied, incorrect hook-up detected, or Emergency Stop engaged.
What to do: Check the HV interlock/key switch status, confirm wiring, release Emergency Stop, and follow the on-screen prompts.

Pinpointing signal is weak or hard to follow

What it usually means: Incorrect mode/pulse rate selected, poor earth return path, or unsuitable locator settings.
What to do: Confirm the selected pinpointing method (pulsed DC vs A-frame), check earthing, and verify the locator is set for the correct frequency/pulse pattern.

Interpreting test results

Your test results should be interpreted in the context of the cable type, length and site conditions.

Testing (sheath insulation)

A stable insulation reading with low leakage current typically indicates an intact sheath.
Unstable values, rising leakage current, or a sudden breakdown event can indicate a defect or moisture ingress.

Prelocation (voltage drop method)

The MFM 10 automatically calculates the distance to the fault after measuring voltage, current and resistance.
If results vary between runs, use the bipolar measurement function to compensate for thermoelectric/galvanic effects, and re-check connection quality at both ends.

Pinpointing

Pulsed DC output supports step-voltage pinpointing when used with a compatible locator.
Low-frequency A-frame pinpointing (3 Hz or 4.8 Hz) is useful when you need clear directional guidance while walking the route.

Logging and reporting

Export log data via USB for traceability, repeat tests and maintenance records.

Software and firmware updates

MFM10

latest version

MFM10 update

latest version

1590

zip 11.13 MB

MeggerBook

MeggerBook and MeggerBook Lite

latest version

MeggerBook & MeggerBook Lite Software

latest version

4.4.0

What’s new in version 4.4.0

Updates

Incorrect reset of the propagation speed v/2 on the Settings page
Incorrect behavior of the Settings page when the virtual keyboard is absent
Crash when editing report templates
Preview pages are displayed in letter format
During an active search, entries that are not visible can be selected
The cable description in the report does not display any special characters (including ü¼ö¶ä¤)
In TDR analyses, the velocity is always given in v/2

Improvements

Database version check
Refresh on cable changes
Phase-resolved tanDelta trend data in BA TanDelta MWT
Improve handling of Winkis data (Sqlite2)
Save import/export folder path in MeggerBook
Update TanDelta standards
Display GPS status on map
Display the sleeve or cable type when hovering over the cable run

New Features

Display TE measurements properly in the activity view in MeggerBook
The radio options on the "Language settings" page are not working well
Extremely large Megger-mcb files due to PDF reports made manageable

The setup file below is suitable for the installation of both MeggerBook (full version) and MeggerBook Lite (free limited version).

When started with after adding the electronic license key into the installed software, the software starts as MeggerBook full version which allows for easy and comprehensive data evaluation, data archiving, cable management and report creation. A personal quotation for a certain number of licenses can be requested here . The new electronic license key allows for 3 devices to have MeggerBook full version installed on them.

The dongle key licenses from older versions of MeggerBook are not supported with this newer version. Updated electronic license keys can be requested here for previous customers.

Without the required software license key the software starts as MeggerBook Lite which allows for seamless report creation and offers some of the features as the full version while limiting the data storage options as follows:

• Measurements, analyses and reports are not permanently stored in the database

• While cable import and storage are not limited, a maximum of 5 cables can be created using the cable editor of the Lite Edition

At this time, the software can handle the measurement and test data of the following Megger devices:

Test vans: Centrix 2.0, Primeon Centrix City, Compact City, R30 2.0, Variant

Test systems: VLF Sine 34 / 37 / 45 / 62, VLF CR 40/60, TDS 40/60, Easytest 20, MFM 10

TDRs: Teleflex VX(-P), Teleflex SX-1

Note for test systems VLF Sine Wave 45 and VLF Sine Wave 62:

Data of these test systems can only be imported into the software, if the test systems is equipped with firmware version 3.14 or higher. The latest firmware can be found here (VLF Sine Wave 45) and here (VLF Sine Wave 62).

x-msdos-program 111.56 MB

FAQ / Frequently Asked Questions

How do I know which pulse rate to use?

Select the pulse rate recommended for your locator/A-frame. The MFM 10 supports both 3 Hz and 4.8 Hz options for A-frame methods.

What is the maximum test object capacity?

The internal discharge is designed for test objects up to 10 µF. Do not exceed this limit.

Can I test multiple conductors at once?

In low-risk situations, conductors may be bridged for a single test, provided the total capacitance stays within the permitted limit. If any issue is indicated, test each conductor individually.

How do I export results?

Use the USB interface to export log data for reporting and maintenance records.

Where can I get service or annual maintenance?

Contact Megger or an authorised service partner for inspection, calibration and maintenance.