MV Asset Management : Maximising your Medium Voltage Cable Performance

Asset management is the systematic and coordinated activities that optimally manage performance, risk and expenditure over the lifecycle - maximising long-term profits whilst delivering high service levels within acceptable and manageable risks.

That sounds a lot, but effective asset management practices are crucial for maintaining performance in every type of cable. That being said, it’s especially important when it comes to medium voltage cables (MV) - critical to operations but likely installed out of sight, buried underground or in cable ducts, or on cable ladder overhead.  The operating conditions and stressors of these spaces – soil thermal resistivity, moisture, extreme temperatures and more – can accelerate material ageing and cause irreversible changes to cable structure. And let's not forget, these cables aren’t always the most visible components, making them easy to overlook when it comes to maintenance.

Ensure your MV systems continue to run as smoothly as possible with our top 5 installation and asset management tips, designed to help you mitigate risks, prolong cable life and reduce downtime due to unexpected failures.

Remember: The following necessarily assumes that the correct cable specification has been made to best suit the performance demands, installation design, and environmental challenges the cable will face during its lifetime operations. Consider for instance whether the cable is running under full load at maximum operating temperature, or whether it is part of a redundant fail-over system. The stress on the cable will be different.

It also assumes the manufacture is compliant with all relevant standards (independent testing such as it undertaken in The Cable Lab is recommended to confirm this prior to installation). Without this, even the most conscientious asset management programme will not be able to outweigh and pre-empt the potential pitfalls.

For assistance with specification, please get in touch to discuss your project.

Top 5 Tips for Cable Maintenance & System Longevity

1. Plan for success and follow best practice during installation

Carefully consider the installation environment (does it differ through the cable run, what parameters do you need to be aware of); are there obstacles; is the route crossing existing cables which need to be taken into account. Preventative actions are better than corrective actions!

Every cable will have a minimum bending radius, maximum sidewall pressure, and a maximum pulling tension which should not be compromised otherwise it risks damaging the conductor and/or the insulation which can compromising cable performance. Be careful to assess the installation route against these – routing around obstacles, under walls, or simply taking a less-than-straight path may mean adaptations have to be made to the installation design to avoid damage.

2. Careful calibration of cables and accessories

Accessory interface contamination can cause a focus of electric stress, leading to unnecessary damage. Failure to use the right sized terminations or joints, and incorrect use of jointing tools can also lead to catastrophic cable failures exactly where you need a reliable connection most.

Most cable standards allow for a small degree of manufacturing tolerance in overall diameter – be sure your accessories will match or agree tolerances in advance. You should never be in the situation where you’re having to try to make something fit onsite during installation. Avoid these issues by selecting the appropriate cable accessories for your project. And if you're unsure, get in touch with us. Our team of technical experts can recommend the right components for you.

3. Commissioning testing and ongoing offline assessments

At the commissioning stage, it is essential that the cables are fully tested to ensure compliance with the requirements of the system in which they are operating. For ongoing maintenance, fault finding techniques such as “thumping” can be effective, but exposing the cables to high voltages can create additional problems (by stressing the insulation) in addition to locating faults. Be sure that thumping is kept to a minimum - or use in conjunction with TDR to ensure that the location of the fault is narrowed down.

Stay ahead of the game with offline VLF partial discharge (PD) and tan delta (TD) to establish the true condition of the cable. This can be very effective alongside IR (infrared) inspections of your connectors. These non-intrusive tests can identify hot spots that may signify loose connections or other issues, reducing the risk of equipment failure ahead of time.

4. Conduct regular inspections

MV cables often fly under the maintenance radar, so it's crucial to stay vigilant. Conduct regular visual inspections to catch any signs of wear, damage or deterioration. Even if cables are buried or inaccessible, there are ways to keep an eye on them – see below. Acting early can help prevent wider knock-on effects on your network, allowing planned maintenance and minimising the need for urgent/critical works. The monitoring tools available will help you identify potential points of failure so they can be acted on accordingly.

a) Consider investing in real-time monitoring tools

Invest in live, online and condition-based monitoring to keep tabs on your critical MV cable networks. These tools capture diagnostic data in minutes, potentially extending cable lifespans by years.

Switchgear and cable monitor (SCM) systems continuously monitor partial discharge (PD) and provide valuable insights into the health of your MV cables’ insulation without taking the network out of service. This helps avoid disruptions and downtime, ensuring your operations run smoothly.

 b) Practise the proper cable care techniques

With the proper care, aging cable systems can outperform newer, less well maintained cable systems. Regular route inspections and the use of marker stones and warning signs can prevent future damage and keep cables in service for as long as possible.

5. Review the original parameters

From time-to-time it is worth considering if there have been changes to the performance demands, the installation design, or the environmental challenges the cables are faced with. Many installations will be subject to add-ons, expansions, and adaptations. The system designed may no longer be the system you need to support operations. It may also be that these expansions change the profile of the overall installation – for example, are the cables still in the same installation configuration or has the ambient temperature changed?

If any of the original parameters that determined the cable specification have changed then the asset management plan must step up to pinpoint the areas affected by change and the potential impact on the network. Whilst there may be no immediate effects, additional close monitoring can help mitigate risk.

 

Eland Cables: The first step in optimising Medium Voltage cable performance

By implementing regular inspections on cables that have undergone rigorous testing processes, you can identify and address potential issues with your Medium Voltage networks before they lead to costly failures.

Start the process by selecting a cable supplier that assures quality and compliance through rigorous impartial testing. At Eland Cables we run hundreds of tests each week in our ISO/IEC 17025 & IECEE CBTL accredited Cable Lab to ensure our Medium Voltage cables meet the performance demands and regulatory requirements necessary to support cable lifespan and longevity of operations.

Quality Matters.

For more information on our MV cables and testing protocols, speak to the team.