Advanced Line Resonance Analysis (LIRA) for Cable Condition Monitoring

Line Resonance Analysis (LIRA): Next generation, non-destructive cable condition assessment 

LIRA is a non-destructive cable testing tool that operates without energising cables to high voltages, making it safe and ideal for high-risk environments.

Why choose LIRA?

LIRA can be carried out on electrical cables hundreds of kilometres in length and is becoming increasingly effective for condition monitoring, or fault location, in long length cables (for example submarine cables connecting off-shore platforms to the grid).

LIRA can test for and detect numerous types of faults and defects in insulation including temperature and radiation damage, moisture ingress and mechanical impact to name a few.

The mechanics of LIRA

LIRA relies on the correlation between the insulation’s condition and its dielectric constant, primarily focusing on capacitance. It calculates the impedance spectrum, both amplitude and phase, as a function of the applied signal over a wide frequency band.

Changes in the cable permittivity and radius affect the localised impedance, leading to reflections. The most significant reflection typically occurs at the end of the cable.  LIRA leverages this by analysing standing wave patterns in short and open circuits. This approach enables an accurate detection of impedance anomalies, making it easy to spot any changes or issues in the cable.

Detect the following cable faults with LIRA

• Global insulation degradation
• High temperature damage
• Moisture ingress
• Radiation damage
• Mechanical effects/defects

Features and Benefits

• Capable of being used on cables that are hundreds of kilometres in length
• Suitable for cable testing where energising to working voltage is of concern
• Can be used to provide initial cable ‘fingerprinting’. Easily recognise when a fault has occurred on a cable.
• Accurate detection of changes in impedance
• Localising of faults to within 0.3% of the cable length
• Can locate joints on circuits where they would be otherwise unknown

*Note: For the highest sensitivity, testing from both ends of a cable is recommended to overcome some signal loss across multiple impedance changes, although this is not a necessity.

Assess the health of your cable assets with LIRA today. Speak to one of our experts!