With the increasing proliferation of electric vehicles, and the new “fast charging” technology, the need for a reliable and safe charging infrastructure is also increasing. Both the actual charging devices and the connected vehicles themselves need to be protected against overvoltages, as both have sensitive electronic components.
Protecting equipment against the effects of lightning strikes as well as against power fluctuations on the network side is necessary. A direct hit by a lightning strike is devastating and hard to protect against, but the real danger for electronic devices of all kinds comes from the resultant electrical surge. In addition, all grid-side electrical switching operations that are connected to the grid, are potential sources of danger for the electronics in electric cars and charging stations. Short-circuits and earth faults can also be counted among the possible sources of damage to this equipment.
In order to be prepared against these electrical risks, it is absolutely necessary to take appropriate protective measures. Safeguarding expensive investments is imperative, and corresponding electrical standards prescribe the appropriate ways and means of safeguarding. There is a lot to consider, because the different sources of danger cannot be addressed with one solution for everything. This paper serves as an aid to identifying risk scenarios and the associated protection solutions, both on the AC and DC side.
Evaluate scenarios correctly
Overvoltages caused, for example, by direct or indirect lightning strikes into the alternating current (AC) network must be diminished up to the input of the main distributor of the EV charging device. It is therefore recommended to install Surge Protection Devices (SPDs) which conduct the impinging surge current to earth, directly after the main circuit breaker. A very good basis is provided by the comprehensive lightning protection standard IEC 62305-1 to 4 with its application examples. There, the risk assessment as well as external and internal lightning protection are discussed.
The lightning protection levels (LPL), which describe various mission critical applications, are decisive in this case. For example, LPL I includes the aircraft towers, which must still be operational even after a direct lightning strike (S1). LPL I also considers hospitals; where equipment must also be fully functional during thunderstorms and protected from fire hazard so that people are always as safe as possible.
In order to evaluate the corresponding scenarios, it is necessary to assess the risk of a lightning strike and its effects. For this purpose, various characteristics are available, ranging from direct impact (S1) to indirect coupling (S4). In combination with the respective impact scenario (S1-S4) and the identified application type (LPL I-/ IV), the corresponding products for lightning and surge protection can be determined.
The lightning protection levels for internal lightning protection are divided into four categories: LPL I is the highest level and is expected at 100 kA for the maximum load of a pulse inside an application. This means 200 kA for a lightning strike outside the respective application. Of this, 50 percent is discharged into the ground, and the “remaining” 100 kA is coupled into the interior of the building. In the case of a direct lightning strike risk S1, and an application of lightning protection level I (LPL I), the corresponding network must therefore be considered. The overview to the right provides the required value per conductor:
The correct surge protection for the electrical charging infrastructure
Similar considerations need to be applied to electrical charging infrastructure. In addition to the AC side, the DC side must also be considered for some charging column technologies. It is therefore necessary to adopt the scenarios and values presented for the charging infrastructure of electric vehicles. This simplified schematic illustration shows the structure of a charging station. A lightning protection level LPL III/IV is required. The below picture illustrates the scenarios S1 to S4:
These situations must be countered with lightning and surge protection. The following recommendations are available in this regard:
- For charging infrastructure without external lightning protection (induction current or mutual induction; values per conductor): only indirect coupling occurs here and only overvoltage protection precautions need to be taken. This is also shown in Table 2 on the pulse shape 8/20 μs, which stands for the overvoltage pulse.
In this case showing direct and indirect coupling through an overhead line connection, the charging infrastructure has no external lightning protection. Here an increased lightning risk is discernible through the overhead line. It is therefore necessary to install lightning protection on the AC side. A three-phase connection requires at least 5 kA (10/350 μs) protection per conductor, see Table 3.
- For charging infrastructure with external lightning protection: The illustration on page 4 shows the designation LPZ, which stands for the so-called Lightning Protection Zone – i.e. the lightning protection zone that results in a definition of protection quality. LPZ0 is the outer area without protection; LPZ0B means that this area is “in the shadow” of the outer lightning protection. LPZ1 refers to the building entrance, for example the entry point on the AC side. The LPZ2 would represent a further sub-distribution inside the building.
In our scenario we can assume that products of LPZ0 / LPZ1 lightning protection products are required which are accordingly designated as T1 products (Type 1) (Class I per IEC or coarse protection). In the transition from LPZ1 to LPZ2 there is also talk of overvoltage protection T2 (Type 2), Class II per IEC or medium protection.
In our example in Table 4, this corresponds to an arrester with 4 x 12.5 kA for the AC connection, i.e. a total lightning current carrying capacity of 50 kA (10/350 μs). For AC/DC converters, appropriate overvoltage products must be selected. Attention: On the AC and DC side this must be done accordingly.
Meaning of external lightning protection
For the charging stations themselves, the choice of the correct solution depends on whether the station is within the protection zone of the external lightning protection system. If this is the case, a T2 arrester is enough. In outdoor areas, a T1 arrester must be used according to the risk. See Table 4.
Important: Other sources of interference can also lead to overvoltage damage and therefore require appropriate protection. These can be switching operations on electrical systems that emit overvoltages, for example, or those that occur through lines inserted into the building (telephone, bus data lines).
A helpful rule of thumb: All metallic cable lines, such as gas, water or electricity, that lead into or out of a building are potential transmission elements for surge voltages. Therefore, in a risk assessment, the building should be examined for such possibilities and appropriate lightning / surge protection should be considered as close as possible to the sources of interference or building entry points. Table 5 below provides an overview of the different types of surge protection available:
The right type and SPD to choose
The smallest clamping voltage should be applied to the application to be protected. It is therefore important to select the correct design and the suitable SPD.
Compared to conventional arrester technology, LSP’s hybrid technology ensures the lowest overvoltage load on the equipment to be protected. With optimum overvoltage protection, the equipment to be protected has a negligible current flow of a safe size and low energy content (I2t) – the upstream residual current switch is not tripped.
Back to the specific application of charging stations for electric cars: If charging devices are more than ten meters away from the main distribution board in which the primary surge protection is located, an additional SPD must be installed directly at the terminals of the AC side of the station in accordance with IEC 61643-12.
SPDs at the input of the main distribution board must be able to derive partial lightning currents (12.5 kA per phase), categorized as Class I according to IEC 61643-11, in accordance with Table 1, in the AC network without mains frequency in the event of lightning strikes. In addition, they must be free of leakage current (in pre-metering applications) and insensitive to short-term voltage peaks that can occur due to faults in the low-voltage network. This is the only way to guarantee a long service life and high SPD reliability. UL certification, ideally type 1CA or 2CA according to UL 1449-4th, ensures worldwide applicability.
LSP’s hybrid technology is ideally suited for AC protection at the input of the main distribution board according to these requirements. Due to the leakage-free design, these devices can also be installed in the pre-meter area.
Special feature: Direct current applications
Electric mobility also makes use of technologies such as rapid charging and battery storage systems. DC applications are specifically used here. This requires dedicated arresters with correspondingly extended safety requirements, such as larger air and creepage distances. Since the DC voltage, in contrast to the AC voltage, does not have a zero crossing, the resulting arcs cannot be automatically extinguished. As a result, fires can easily occur which is why an appropriate surge protection device must be used.
Since these components react very sensitively to overvoltages (low interference immunity), they must also be protected with appropriate protective devices. Otherwise they can be pre-damaged, which significantly shortens the service life of the components.
With its product FLP-PV1000, LSP offers a solution designed for use in the DC range. Its main features include a compact design and a special high-performance disconnecting device that can be used to safely extinguish a switching arc. Due to the high self-extinguishing capacity, a prospective short-circuit current of 25 kA can be separated, as can be caused, for example, by battery storage.
Because the FLP-PV1000 is a Type 1 and Type 2 arrester, it can be used universally for e-mobility applications on the DC side as lightning or surge protection. The nominal discharge current of this product is 20 kA per conductor. To ensure that insulation monitoring is not disturbed, it is recommended to use a leakage current-free arrester – this is also guaranteed with FLP-PV1000.
Another important aspect is the protective function in the event of overvoltages (Uc). Here FLP-PV1000 offers safety up to 1000 volts DC. As the protection level is <4.0 kV, the protection of the electric vehicle is ensured at the same time. A rated impulse voltage of 4.0 kV must be guaranteed for these cars. Thus if the wiring is correct the SPD also protects the electric car being charged. (Figure 3)
FLP-PV1000 offers a corresponding color display that provides convenient status information about the viability of the product. With an integrated telecommunications contact, evaluations can also be carried out from remote locations.
Universal protection scheme
LSP offers the most comprehensive product portfolio on the market, with a device for any scenario and many times more than just one. For all of the above cases LSP products can reliably secure the entire charging infrastructure – both universal IEC&EN solutions and products.
Protect the charging infrastructure and electric vehicles from lightning and surge damage according to the requirements of IEC 60364-4-44 clause 443, IEC 60364-7-722 and VDE AR-N-4100.
Electric vehicles – clean, fast and quiet – are becoming increasingly popular
The quickly growing e-mobility market is sparking great interest in industry, utilities, communities and with citizens. Operators aim to make a profit as soon as possible, so it is vital to prevent downtime. This is done by including a comprehensive lightning and surge protection concept at the design stage.
Safety – a competitive advantage
Lightning effects and surges jeopardise the integrity of the sensitive electronics of charging systems. It is not only charging posts which is at risk, but the customer’s vehicle. Downtime or damage can soon get expensive. Beside the repair costs, you also risk losing the trust of your customers. Reliability is the top priority in this technologically young market.
Important standards for e-mobility
Which standards have to be considered for the e-mobility charging infrastructure?
The IEC 60364 standard series consists of installation standards and therefore has to be used for fixed installations. If a charging station is not movable and connected via fixed cables, it falls under the scope of IEC 60364.
IEC 60364-4-44, clause 443 (2007) provides information on WHEN surge protection is to be installed. For example, if surges can affect public services or commercial and industrial activities and if sensitive equipment of overvoltage category I + II … is installed.
IEC 60364-5-53, clause 534 (2001) deals with the question of WHICH surge protection should be selected and HOW to install it.
What is new?
IEC 60364-7-722 – Requirements for special installations or locations – Supplies for electric vehicles
As of June 2019, the new IEC 60364-7-722 standard is mandatory for planning and installing surge protection solutions for connection points which are accessible to the public.
722.443 Protection against transient overvoltages of atmospheric origin or due to switching
722.443.4 Overvoltage control
A connecting point accessible to the public is considered to be part of a public facility and must therefore be protected against transient overvoltages. As before, surge protective devices are selected and installed according to IEC 60364-4-44, clause 443 and IEC 60364-5-53, clause 534.
VDE-AR-N 4100 – Basic rules for connecting customer installations to the low-voltage system
In Germany, VDE-AR-N-4100 must be additionally observed for charging posts which are directly connected to the low-voltage system.
VDE-AR-N-4100 describes, among other things, additional requirements on type 1 arresters used in the main power supply system, for example:
- Type 1 SPDs must comply with the DIN EN 61643 11 (VDE 0675 6 11) product standard
- Only voltage-switching type 1 SPDs (with spark gap) may be used. SPDs with one or more varistors or parallel connection of a spark gap and a varistor are prohibited.
- Type 1 SPDs must not cause operating current resulting from status displays, e.g. LEDs
Downtime – Don’t let it come to that
Protect your investment
Protect charging systems and electric vehicles from costly damage
- To the charge controller and battery
- To the control, counter and communication electronics of the charging system.
Protecting the charging infrastructure
Lightning and surge protection for electromobility charging stations
Charging stations are required where electric vehicles are parked for an extended period of time: at work, at home, at park + ride sites, in multi-storey car parks, in underground car parks, at bus stops (electric busses), etc. Therefore, more and more charging stations (both AC and DC) are currently being installed in private, semi-public, and public areas – consequently there is an increasing interest in comprehensive protection concepts. These vehicles are too expensive and the investments too high to run the risk of lightning and surge damage.
Lightning strikes – Risk for the electronic circuitry
In case of a thunderstorm, the sensitive electronic circuitry for the controller, counter and communication system is particularly at risk.
Satellite systems whose charging points are interconnected can be immediately destroyed by just a single lightning strike.
Surges also cause damage
A nearby lightning strike often causes surges which damage the infrastructure. If such surges occur during the charging process, it is highly likely that the vehicle will also be damaged. Electric vehicles typically have an electric strength of up to 2,500 V – but the voltage produced by a lightning strike can be 20 times higher than that.
Protect your investments – Prevent damage
Depending on the location and type of threat, an individually adapted lightning and surge protection concept is required.
Surge protection for electric mobility
The market for electric mobility is on the move. Alternative drive systems are registering a steady increase in registrations, and particular attention is also being paid to the need for nationwide charging points. For example, according to calculations by the german BDEW association, 70.000 normal charging points and 7.000 quick charging points are required for 1 million e-cars (in germany). Three different charging principles can be found on the market. In addition to wireless charging based on the induction principle, which is still relatively uncommon in europe (at the moment), battery exchange stations have been developed as a further alternative as the most convenient charging method for the user. The most widespread charging method, however, is wired conductive charging … and this is precisely where reliable and carefully designed lightning and surge protection must be ensured. If the car is considered a safe place to be during thunderstorms due to its metal body and thus following the principle of Faraday’s cage, and if the electronics are also relatively safe from hardware damage, the conditions change during conductive charging. During conductive charging, the vehicle electronics are now connected to the charging electronics, fed by the power supply system. Overvoltages can now also couple into the vehicle via this galvanic connection to the power supply network. Lightning and overvoltage damage is much more likely as a result of this constellation and the protection of the electronics against overvoltages is becoming increasingly important. Surge protection devices (SPD) in the charging infrastructure offer a simple and efficient way of protecting the electronics of the charging station and, in particular, those of the car from cost-intensive damage.
A typical installation location for such loading equipment is in the private environment in the garages of private homes or underground car parks. The charging station is part of the building. The typical charging capacity per charging point here is up to 22 kW, the so-called normal charging, whereby according to the German current application rule VDE-AR-N 4100 Charging devices for electric vehicles with rated power ≥ 3.6 kVA must be registered with the grid operator, and even require prior approval if the total rated power to be installed is > 12 kVA. IEC 60364-4-44 should be specifically mentioned here as the basis for determining the requirements of the surge protection to be provided. It describes “Protection against transient overvoltages due to atmospheric influences or switching operations”. For the selection of the components to be installed here, we refer to IEC 60364-5-53. A selection aid created by LSP facilitates the selection of the arresters in question. Please look here.
Charge mode 4
Last but not least, charging mode 4 describes the so-called fast charging process with > 22 kW, mostly with DC up to currently typically 350kW (perspectively 400kW and more). Such charging stations are mainly found in public areas. This is where IEC 60364-7-722 “Requirements for special operating facilities, rooms and systems – Power supply for electric vehicles” comes into play. An overvoltage protection against transient overvoltages due to atmospheric influences or during switching operations is explicitly required for charging points in publicly accessible facilities. If the charging stations are installed outside the building in the form of charging points, the required lightning and surge protection is selected according to the selected installation site. The application of the lightning protection zone (LPZ) concept in accordance with IEC 62305-4:2006 provides further important information on the correct design of lightning and surge arresters.
At the same time, the protection of the communication interface must be taken into account, especially for wall boxes and charging stations. This extremely important interface should not only be considered due to the recommendation of IEC 60364-4-44, as it represents the link between the vehicle, the charging infrastructure and the energy system. Here too, protection modules tailored to the application ensure the reliable and safe operation of electric mobility.
Sustainable mobility implications in surge protection systems
For an efficient and safe electrical vehicle charge, a specific instruction has been elaborated within the Low Voltage Regulation for the installations intended for that purpose: the ITC-BT 52. This instruction stresses the necessity to have specific material in transient and permanent surge protection. LSP has tailored solutions for compliance with this standard.
Although currently less than 1% of the Spanish automotive industry is sustainable, it is estimated that in 2050 there will exist around 24 million electric cars and in ten years’ time the amount will increase to 2,4 million.
This transformation in the number of cars slows down the climate change. However, this evolution also implies the adaptation of the infrastructures that will supply this new clean technology.
Protection against overvoltages in the charge of electric vehicles
The efficient and safe charge of electric cars is a key issue in the sustainability of the new system.
This charge should be made safely, guaranteeing the vehicle and the electric system conservation, with all the protection devices needed, including those related to overvoltages.
In this regard, charging installations for electric vehicles must comply with the ITC-BT 52 to protect all the circuits against transient and permanent surge protection that can damage the vehicle during the loading process.
The regulation was published by a royal decree in the Spanish Official Bulletin (Real Decreto 1053/2014, B.O.E), in which a new Complementary Technical Instruction ITC-BT 52 was approved: «Facilities for related purpose. Infrastructure for the charging of electric vehicles».
Instruction ITC-BT 52 of the Electrotechnical Low Voltage Regulation
This instruction requires to have new facilities for the supply of the charging stations as well as the modification of existing facilities that are supplied from the electric power distribution network to the following areas:
- In new buildings or parking lots a specific electric facility must be included for the charging of electric vehicles, executed in accordance with the established in the referred ITC-BT 52:
- a) in parking lots of buildings with a horizontal property regime a main conduction must be run through community zones (through tubes, channels, trays, etc.) so that it is possible to have branches connected to the charging stations located in the parking spaces, as it is described in section 3.2 of the ITC-BT 52.
- b) in private parking lots in cooperatives, businesses or offices, for staff or associates, or local vehicle depots, the necessary facilities must supply one charging station for every 40 parking spaces.
- c) in permanent public parking lots, the necessary facilities to supply a charging station for every 40 seats will be guaranteed.
It is considered that a building or a parking lot is newly constructed when the construction project is presented to the corresponding Public Administration for its processing on a date following the entry of the Royal Decree 1053/2014.
The buildings or parking lots prior to the publication of the royal decree had a period of three years to adapt to the new regulations.
- In the street, the necessary facilities must be considered to provide supply to the charging stations located in the spaces for electric vehicles planned in the regional or local Sustainable Mobility Plans.
What are the possible schemes for the installation of charging points?
The installation diagrams for the charge of electric vehicles that have been foreseen in the instruction are the following:
Collective or branch scheme with a main counter in the origin of the installation.
Individual scheme with a common counter for the house and the charging station.
Individual scheme with a counter for each charging station.
Scheme with circuit or additional circuits for charging electric vehicles.
Surge protection devices for the ITC-BT 52
All circuits must be protected against temporary (permanent) and transient overvoltages.
Transient surge protection devices must be installed in the proximity of the origin of the facility, or in the main board.
In November 2017, the Technical Guide of application of the ITC-BT 52 was published, where the following is recommended:
– To install a type 1 transient surge protection upstream of the main counter or next to the main switch, located at the entrance of the centralization of counters.
– When the distance between the charging station and the transient surge protection device located upstream is greater than or equal to 10 meters, it is recommended to install an additional transient surge protection device, type 2, next to the charging station or inside it.
Solution against transient and permanent overvoltages
In LSP we have the right solution for an effective protection against transient and permanent surges:
To protect against type 1 transient overvoltages, LSP has the FLP25 series. This element guarantees a high protection against transient overvoltages for power supply lines at the entrance of the building, including those produced by direct lightning discharges.
It is a type 1 and 2 protector according to the standard IEC/EN 61643-11. Its main characteristics are:
- Impulse current per pole (limp) of 25 kA and a protection level of 1,5 kV.
- It is formed by gas discharger devices.
- It has signs for the state of the protections.
For protection against type 2 transient overvoltages and permanent overvoltages, LSP recommends the SLP40 series.
Protect your electric vehicle
An electric vehicle can withstand a shock voltage of 2.500V. In case of an electrical storm, the voltage that could be transmitted to the vehicle is even 20 times higher than the voltage it can withstand, causing irreparable damages in all the system (controller, counter, communication systems, vehicle), even when the impact of the beam occurs at a certain distance.
LSP puts at your disposal the necessary products to protect the charging points against transient and permanent surges, ensuring the conservation of the vehicle. In case you are interested in acquiring the protection against overvoltages, you can rely on the help of our expert staff in the matter here.
Special scenarios cannot be covered comprehensively with universal solutions – just as a Swiss Army Knife can’t replace a well-equipped tool set. This also applies to the environment of EV charging stations and electric cars, especially since appropriate measuring, control and regulation instruments should ideally also be included in the protection solution. It is important both to have the right equipment and to make the right choice depending upon the situation. If you take this into consideration, you will find a high-reliability business segment in electro mobility – and a suitable partner in LSP.
Electromobility is a hot topic of present times and of the future. Its further development depends on the timely construction of an appropriate network charging stations which have to be safe and error-free in operation. This can be achieved by using LSP SPDs installed in both the power supply and inspection lines where they protect the electronic components of the charging stations.
Protection of the power supply mains
Overvoltages can be dragged-in into the charging station technology in a number of ways via the power supply line. Problems due to overvoltages arriving through the distribution network can reliably be minimized by using LSP high-performance lightning stroke current arresters and SPDs of the FLP series.
Protection of measuring and control systems
If we want to operate the above systems properly, we have to prevent the possibility of modification or deletion of data contained in the control or data circuits. The above mentioned data corruption may be caused by overvoltages.
LSP is a technology follower in AC&DC surge protection devices (SPDs). The company has grown steadily since its inception in 2010. With more than 25 employees, its own test laboratories, LSP product quality, reliability and innovation are guaranteed. Most of surge protection products are tested and certified independently to international standards (Type 1 to 3) according to IEC and EN. Customers come from a wide range of industries, including building/construction, telecommunications, energy (photovoltaic, wind, power generation in general and energy storage), e-mobility and rail. More information is available at https://www.LSP-international.com.com.