KEMA Labs: Reliability starts before energisation

By Floris Schulze, Global Director, Utilities, KEMA Labs

As power networks expand and modernise to support electrification, renewable integration and cross-border interconnections, one reality remains unchanged: reliability is not achieved by design alone. It must be proven.

For utilities and transmission system operators facing unprecedented investment cycles, the pressure to deliver projects quickly is intense. Yet the consequences of equipment failure have never been greater. A single outage can disrupt critical infrastructure, create substantial economic losses and damage public confidence in the power system. In this environment, rigorous testing has become more than a technical requirement. It is a strategic safeguard.

Recent testing experience at KEMA Labs, the testing, inspection and certification (TIC) business unit of CESI Group, highlights a challenge that deserves greater industry attention. Despite decades of advances in manufacturing technologies, materials science and digital engineering tools, approximately one in four transmission and distribution components submitted for IEC type testing fails to meet the required standards on its first test attempt. For power cable systems and accessories, failure rates can be even higher.

This finding raises an important question: if technology is improving, why are failure rates not declining?

The hidden cost of cost reduction

The answer lies partly in the growing commercial pressure on manufacturers and supply chains. Utilities worldwide are seeking to accelerate investment programmes, while equipment suppliers are working at maximum capacity to meet rising demand.

In many cases, technical innovation has been used primarily to optimise production costs rather than to significantly improve product robustness. The result is a market in which certification and independent testing have become essential tools for distinguishing genuinely high-quality products from those that simply meet commercial expectations.

Power cables provide a particularly interesting example. Medium-voltage joints and terminations frequently experience failures linked to material selection, especially where lower-cost heat-shrink technologies are used. High-voltage cable systems face different challenges, including increasingly complex manufacturing requirements and the entry of suppliers with limited experience in extra-high-voltage applications.

The lesson is clear: electrical infrastructure should be viewed as more than a commodity purchase. Network components are highly engineered assets whose performance directly impacts grid security, operational continuity and public safety.

Why type testing in independent laboratories still matters

International IEC standards provide a robust framework for validating cable performance through type testing and, for higher voltage classes, pre-qualification testing.

Type testing subjects cable systems to a combination of electrical, thermal and mechanical stresses that replicate real operating conditions. For high-voltage applications, pre-qualification testing goes further, exposing systems to long-term loading cycles and elevated voltages over extended periods.

These tests are designed not merely to verify compliance, but to uncover weaknesses before equipment reaches the field.

At a time when simulation tools are becoming increasingly sophisticated, some organisations are tempted to rely more heavily on modelling and less on physical testing. While digital engineering undoubtedly has an important role to play, laboratory testing remains essential for exposing equipment to realistic operating and fault conditions in a controlled environment.

The energy transition is introducing new uncertainties into network operation, including higher asset utilisation rates, changing load profiles and increasing exposure to extreme weather events. Under such conditions, assumptions are rarely enough.

The HVDC challenge

While offering significant benefits, the growth of high-voltage direct current (HVDC) transmission is adding another layer of complexity.

HVDC systems are becoming fundamental to offshore wind integration, long-distance power transmission and international interconnectors. However, testing experience suggests that HVDC cable technology is still evolving, with failure rates that appear higher than those typically observed in conventional AC applications.

KEMA Labs has been closely involved in this development, including pioneering tests on 525 kV HVDC cable systems and transient overvoltage scenarios. These projects demonstrate how the industry is moving beyond traditional qualification methods to address the new electrical stresses introduced by modern transmission architectures.

As HVDC deployment accelerates globally, independent verification will become increasingly important to ensure long-term network resilience.

Reliability does not end at the factory gate

Even a successfully type-tested cable system faces numerous risks after production.

Transport, storage, handling, installation and jointing activities can all introduce defects capable of reducing service life or triggering premature failure. The challenge is particularly significant for cable accessories, many of which are installed on site under demanding environmental conditions.

This is why commissioning testing has become such a critical stage of project delivery.

On-site testing, typically combining overvoltage withstand testing and partial discharge measurements, enables utilities to identify issues before energisation. Industry data consistently show that problems detected during commissioning are far more likely to involve joints and terminations than the cable sections themselves, underlining the importance of installation quality.

The trend is also clear. As cable circuits become longer and more complex, testing requirements are growing. Utilities increasingly demand comprehensive partial discharge diagnostics, while large projects often require multiple resonant test systems operating together to achieve the necessary test voltages.

Although commissioning test failure rates remain relatively low, the consequences of an undetected defect can be severe. Locating and repairing faults on underground or subsea transmission circuits can be costly and time-consuming, making prevention vastly preferable to remediation.

Building confidence in the energy transition

The electricity sector is entering a period of unprecedented change. New technologies, new suppliers and ambitious decarbonisation targets are reshaping the way power systems are designed and operated.

In such a dynamic environment, confidence must be earned through evidence.

Independent type testing, certification and on-site commissioning represent some of the most effective risk-reduction measures available to utilities and asset owners. They provide objective evidence that equipment can withstand the conditions it is expected to encounter during its operational life.

For network operators seeking to build resilient infrastructure for the future, reliability starts long before energisation. It starts with testing.

And in an increasingly complex energy landscape, that principle has never been more relevant.