Tom Mennell, Technical Standards Manager, Power Systems UK&I at Schneider Electric, outlines the critical role of outdoor low-voltage assemblies in enabling efficient and safe EV charging infrastructure.
As societies move towards a carbon neutral future, electric vehicles are becoming increasingly important. Recently the International Energy Agency predicted that 17 million electric and hybrid vehicles will be sold this year, up more than 20% compared with 2023. This follows new Government legislation at the start of the year to drive EV adoption.
However, in order to make the EV dream a reality, we need to have the infrastructure in place to support it. Whilst many vehicles will be charged from homes, using a domestic electricity supply, it is also essential that our public spaces are future-proofed for the EV revolution.
We must install electric chargers in vast quantities across the UK. And these electric chargers, especially those in public charging hubs and service stations must be reliable.
High-power, fast charging is essential if electric vehicles are to win the long-term confidence of drivers and become more widely accessible. However, to achieve it outside the home, a new approach to electricity management – which prioritises outdoor low-voltage assemblies – is needed.
Why outdoor low voltage assemblies are the key to powering an EV future
Low-voltage assemblies are essential to control and protect the supplies to electric vehicle chargers. As most EV charging hubs will be in open spaces, outdoor low-voltage assemblies could offer significant benefits compared with conventional indoor assemblies.
For example, outdoor low-voltage assemblies require less space due to the fact that they do not require additional enclosures, housings or location within a building. This often enables the assembly to be located much closer to the chargers.
In addition to this, installation can be conducted much faster because the assembly is delivered as a single unit. This usually also means that both initial and lifetime cost of the product are reduced.
Because outdoor assemblies can be located much closer to the point of load, the length and size of cable runs can also be substantially reduced. As shorter cable runs result in lower losses, operational costs can be significantly lowered.
However, when it comes to EVs, the charging application is much more demanding than it usually is for low-voltage assemblies. This can present some unique challenges.
The potential challenges and how these can be overcome
One of the most significant challenges with EV charging stations is that traditional electrical systems aren’t designed to handle all circuits operating at full capacity simultaneously. This capability is crucial for EV charging stations, especially during peak usage on hot summer days. To address this, it’s necessary to use higher-rated components that can manage continuous load and high temperatures, ensuring the system remains reliable and safe even under heavy use.
Another critical issue is ensuring safe earth leakage protection. Most EV chargers require a residual current device (RCD) to protect against electric shocks, as mandated by safety standards. However, EV chargers produce small direct currents (DC) that can interfere with standard RCDs. The solution is to use Type B RCDs, which are better at handling these small DC currents, ensuring reliable protection for users.
Furthermore, protection against electrical faults is essential, particularly in the event of a fault in the electricity supply, such as a broken open protective neutral (PEN) conductor. Such faults pose risks of electric shock and damage to equipment. Installing systems that detect these faults and automatically isolate the faulty part of the network can prevent accidents. For instance, certain offerings on the market will cut off the power supply in case of such faults, providing comprehensive safety.
Condensation inside electrical enclosures can also cause insulation problems and electrical failures, posing a significant challenge. To manage this, it’s beneficial to use enclosures with passive ventilation (IP54 rated) instead of highly sealed ones (IP65 rated). These allow natural air flow, reducing condensation. Additionally, installing heaters controlled by thermostats or humidity sensors can help maintain a stable and dry internal temperature, preventing moisture buildup.
High temperatures from sunlight can impact the performance of electrical systems, especially during peak EV charging times. To counter this, assemblies should be tested under simulated sunlight conditions to ensure they can handle the heat. This testing helps in optimising the design and performance of the system to withstand high temperatures and maintain reliability.
As most assemblies controlling electric vehicle supplies are located in areas accessible to the general public, consideration should be given to safety on those very rare occasions that there is an arcing fault within the assembly. Assemblies used in these applications should be internal arc fault tested to demonstrate that any arc will be contained within the assembly or directed to a safe area.
Given that the infrastructure for EV chargers needs to last a long time, it’s crucial to ensure it resists corrosion, particularly in harsh environments. A practical solution is to use durable materials like pre-galvanised mild steel with high-quality paint finishes that can last up to 25 years. This approach provides excellent protection and is a cost-effective alternative to stainless steel.
EV chargers inherently produce electrical harmonics that can interfere with the power supply, especially when multiple chargers are used together. To manage this, active harmonic filters can be installed. These filters counteract the disturbances, ensuring the power supply remains stable.
Minimising downtime in EV charging stations is crucial for user satisfaction and service reliability. Implementing remote monitoring and control systems can significantly enhance the operation of these stations. Such systems can diagnose problems and enable restoration of service remotely, reducing downtime and improving overall efficiency. An extremely beneficial attribute in the light of the recent legislation, The Public Charge Point Regulations 2023, which requires for networks with rapid charge points, to average 99% availability during each calendar year.
By addressing these challenges with thoughtful design and advanced technology, EV charging stations can be made reliable, safe, and efficient. All of which will contribute to less range-anxiety and stress for EV users, as well as helping to encourage more drivers to make the switch.
Future proofing
As EV charger technology evolves, the supporting low-voltage assemblies must be flexible and upgradeable. The anticipated life of an electrical installation and that of an EV charger are very different, making it vital that any low-voltage assemblies forming part of the installation are adaptable enough to match the needs of new chargers as and when they are installed.
Whether it’s increases in the number and rating of circuits, a shift from manual to automated operation or further adoption of remote monitoring and control, low-voltage assemblies need to be able to adapt. As such, they should include adaptable circuit breaker configurations, upgradeable trip units, and provisions for remote monitoring and control. Selecting a design that accommodates these future needs can reduce downtime and costs over the installation’s life.
Outdoor low-voltage assemblies are crucial for the efficient and safe distribution of electricity to EV chargers. Properly designed and verified assemblies offer numerous benefits: they do not require additional protective buildings, need less installation space, are quicker to install, are future-proofed, and are more cost-effective. By addressing the unique demands of EV charging applications, these assemblies support the transition to a greener, carbon-neutral society.
