There’s currently a massive transition underway — one that will take the world’s automobiles from internal combustion engines to battery-powered technology. One of the main hurdles facing this transition is the installation and operation of nationwide charging networks for these new vehicles.In this article from Phoenix Contact, learn about overvoltage problems with EV chargers, and explore new technical solutions.
Dangers Due to Lightning Strikes and Overvoltages
A large part of charging infrastructure is located outside of buildings and is therefore particularly at risk of being hit by direct or indirect lighting strikes. Therefore, several coordinated protective measures and protective devices are necessary to ensure effective protection against lightning strikes and overvoltage pulses.
Here, a distinction is made between external and internal lightning protection. Comprehensive protection against direct lightning strikes can only be assured if an external lightning protection system is used. The air terminal in an external lightning protection system is designed to “intercept” lightning strikes, dissipate the lightning current safely to ground, and distribute it throughout the ground soil. The internal lightning protection is designed to prevent dangerous sparking within the system and to minimize dangerous potential differences.
The potential differences arising during a lightning discharge often exceed the insulation strength of the electrical components in the charging infrastructure. Therefore, suitable protective measures have to be taken. Two systems are necessary for effective protection:
- A high-performance potential equalization and grounding system.
- A multi-level, coordinated system of surge protective devices.
In addition to overvoltage pulses caused by lightning, the charging infrastructure is also endangered by "man-made" switching operations. Such switching operations can result in dangerous overvoltage pulses that are spread through the electrical conductors and prematurely age the equipment. Simply starting and stopping the charging process is included in these switching operations, which often result in high overvoltage pulses. Damage caused by overvoltage pulses can be prevented and the premature aging of equipment avoided through the use of surge protective devices.
Surge Protection is Mandatory
For decades, operators have been protecting their industrial systems against overvoltages. According to VDE regulations, surge protection for any new installation or comprehensive change to existing electrical systems has been mandatory since 2016, even in private households. This applies to permanently installed equipment, which includes charging stations and home chargers.
In October 2019, the VDE 100 standard in Europe was extended with Part 722], in which the requirements on the charging infrastructure are specified. Publicly accessible charging equipment must also be protected against overvoltage pulses. Part 722 does not go into further detail on the necessary surge protection, but VDE 0100 Part 443 describes when surge protection must be installed - for example, if the public equipment, commercial, or industrial installations are susceptible to impacts. Which surge protective devices are to be selected is regulated in VDE 0100 Part 534.
Tailor-Made Surge Protection
The spatial design and the arrangement of the charging points in the charging infrastructure have a huge influence on the loads that can be expected due to overvoltage pulses and lightning currents. Therefore, a risk assessment should be carried out for each individual charging park, because only then can suitable surge protective devices and the best possible installation locations be selected. The results of a risk assessment performed by experts will simplify the decision as to whether type 1 or type 2 surge protective devices are to be installed at any particular installation location. Even how the device connecting cables are laid can significantly influence the protective effect. Therefore, it is important that the surge protective devices are installed by experts; the device manufacturers themselves also provide corresponding recommendations here.
If direct lightning strikes and energy-rich lightning currents are expected, high-performance type 1 devices should be used. With Valvetrab EV T1/T2, Phoenix Contact provides a tailored protective device for charging infrastructure. If there is not an external lightning protection system or such a system is not necessary, cost-effective type 2 devices also provide sufficient protection. These devices - such as the Valvetrab EV T2 type 2 surge protective device from Phoenix Contact - are installed in the subdistribution stations, charging stations, and home chargers.
In the charging stations, numerous components are also supplied with 24 V DC. The 24 V power supply for this can, for example, be protected using a type 3 surge protective device. Components for communication with a billing system are also installed in charging parks and in charging stations that are publicly accessible. For example, such communication occurs via an Ethernet connection, for which type D1 surge protection is recommended.
Further Components for Infrastructure
Under the "CHARX" name, Phoenix Contact provides a wide range of coordinated charging technology components, both for the electrification of vehicles and for setting up powerful charging infrastructure. All CHARX components have been specifically designed for use in e-mobility applications. The comprehensive product range enables the simple, convenient, and cost-effective construction of AC and DC charging points for electric vehicles (figure 3).
Summary
The charging infrastructure for electric vehicles is just as complex as the vehicle itself. From the power supply and components for visualizing the charging process right through to the cables for Ethernet communication, the charging stations include a large number of sensitive components. These need to be protected - both to ensure that the charging infrastructure has a long service life and to ensure the safety of the user. To also be able to master the mobility transition in terms of the charging infrastructure, it is advantageous that as many of the installed components as possible are coordinated with each other, and thus available from a single source. Users drawing on the comprehensive CHARX product program from Phoenix Contact will benefit from these advantages.
Surge Protection for Charging Stations and Home Chargers
Protection concept in three areas:
- Type 1+2 combined lightning current and surge arresters and type 2 protective devices for the power supply protect feed-in against dangerous overvoltages caused by lightning strikes and switching operations in the grid.
- Type 3 surge protective devices ensure the long-term function of the numerous sensitive components within the charging station.
- The communication components are usually connected via Ethernet and should also be protected.
CHARX Protect Surge Protection
At a glance:
- Complete protection for charging infrastructure thanks to the comprehensive product range
- Uninterrupted continuation of the charging process with a protected power supply
- Protection for the connected e-vehicle with a safe surge protection concept