GSM, OCPP, PLC …? The Mobility House Explains It All
Despite – or perhaps even because of – the fact that charging electric cars is still a very new phenomenon, charging station manufacturers often use different terms for almost identical features. We’ve taken on the challenge of demystifying this confusing terminology. Over the next few pages, you’ll find explanations of the various technical terms and features that you’re likely to come across when choosing which charging station to buy.
Intelligent Charging Stations
Intelligent charging stations are equipped with a communication unit that can control and monitor the charging process (for billing, etc.). This means that, for instance, you can integrate intelligent charging stations into your smart home system, connect them to your photovoltaic plant or use features such as the billing service. The communication interfaces currently used include GSM, Ethernet, WLAN and serial interfaces such as RS485.
also known as mobile radio, SIM, GPRS/UMTS/LTE
The charging station has a mobile modem and can be connected to the Internet via an inserted SIM card. Ideally, you should check whether you have mobile reception in advance. TMH only connects SIM cards to roaming tariffs that automatically choose the best mobile network.
also known as LAN, U/UTP, RJ45
As an alternative to a SIM card, charging stations can also be connected directly to the Internet for data transfer via a LAN cable. It’s often easier to integrate charging stations with a LAN connection into smart home systems than those with a SIM card, as this means that the charging station is already part of the home network and no additional mobile data costs are incurred. However, you will have to connect the charging station to your Internet router via a LAN cable and you may need to make changes to your firewall.
also known as Wi-Fi
You can integrate a charging station into your home network via WLAN as long as it is not too far away from your router. In this case, too, you may need to make changes to the firewall on your wireless router.
also known as a serial interface
Some charging stations can be controlled and monitored locally via a serial interface. For example, you can set the charging power from your PC via a USB adapter or use an additional device for load management.
OCPP (Open Charge Point Protocol) is an open communication standard published by the Open Charge Alliance. OCPP controls the communication between a charging station and a back-end system, focusing on monitoring and billing. OCPP Version 2.0 also includes charging process control in line with ISO 15118.
also known as RFID with local whitelist
You can use RFID to protect your charging station against third-party access. Electric car drivers can use an RFID card to identify themselves when connecting to the charging station. The charging process only begins once the user has been verified. The RFID functions offered by different manufacturers vary in the way in which they verify users, how many users can be verified, and whether the user data can be managed via an app or another system. For example, KEBA and Mennekes use what are known as master RFID cards, which the charging station manager can use directly on the premises to approve new RFID card users (RFID with local whitelist). Mennekes also offers the option of managing or deleting users via an app. ICU requires you to log in to an online portal to add a new user by recording the RFID card number.
PLC (power-line communication) can be used to establish digital communication between a charging station and an electric car. It sends data through the charging cable in the form of high-frequency signals. At the moment, this form of communication technology is only being used for the protocols ISO 15118 and DIN 70121. Its aim is to establish a secure, high-performance data connection for authorisation, status queries, charging control and other functions. This technology has limited compatibility with private applications and currently only works with the smart fortwo electric drive. It is mainly used in public DC CCS charging stations. If, for instance, you use one of these stations to charge your electric car, the current charging status and the number of kilowatt hours charged up are displayed on the charging station.
Z.E. READY is a certificate from the Renault brand. When charging up its electric cars, Renault cannot rule out DC residual currents above 6mA. Therefore, for safety and warranty reasons, Renault has defined its own standards that charging stations must meet before they can charge its electric cars.
Residual Current Device
also known as a residual current circuit breaker, RCD, RCCB
A residual current device, or RCD for short, is used to protect people from electric shocks. A dedicated RCD has been specified for charging electric cars – the RCD type A EV with DC detection, which is a much more affordable solution than the RCD type B otherwise required. You can find out more about why you need an RCD, the different types available and factors to consider when choosing one in our installation tips.
A circuit breaker ensures that the current flowing through the circuit does not exceed the levels permitted by the electrical installation. A current that is higher than the permitted level will trigger the circuit breaker (blowing the fuse). You can find out more about why you need a circuit breaker and which is the right choice for you in our installation tips.
The IP (Ingress Protection) category indicates the environmental conditions in which the charging station can be used. Most charging stations are suitable for outdoor use. The first number indicates the extent to which the charging station is protected against foreign objects and contact (e.g. with tools), while the second number represents the level of protection against water. The charging stations we offer have the protection category IP 44 or IP 54.
What does IP 44 mean? The charging station is protected against contact with tools and against conductive objects and foreign bodies with a diameter > 1.0 mm. It is also protected against splashing water from any direction.
What does IP 54 mean? The charging station is fully resistant to contact and protected against the build-up of dust in its interior. It is also resistant to splashing water from any direction.
The eHZ (elektronischer Haushaltszähler, electronic domestic supply meter) is not readable/intelligent per se – edl21, edl40
A smart meter is an electricity meter that sends the electricity consumption data to other devices and systems. This makes it possible to bill for the energy used to charge a car automatically, for example. There are two types of smart meter:
1. edl40 smart meters that communicate with the meter operator via a communication module (multi-utility controller)
2. edl21 smart meters that send local data to smart home systems
Calibrated Energy Meter
In Germany, all meters – electricity meters in our case – that are used to bill for energy consumption must be calibrated. The Measurement Instruments Directive (MID) is a European Directive on electricity meters. MID-compliant meters do not have to be calibrated before they are put into operation.
also known as a connector
Different charging cables and plugs are used depending on the electric car and the type of charging in question (AC or DC). In principle, the components of the charging cable that is plugged into the car inlet are called the charging connector. The charging plug is the other end of a Mode 3 charging cable that is plugged into the charging station outlet if one is present. If you charge your vehicle using AC current, e.g. at home, a type 1 or type 2 connection is more common. CHAdeMO plugs and Combo1/Combo2 plugs are mainly used at DC charging stations. Find out more about the connection types in our overview of charging cables and plugs.
Load management means operating several charging stations with a limited connection capacity. If the sum of the loads connected to all the charging stations (e.g. four charging stations, each with 22 kW of charging power = connected load of 88 kW) is greater than the overall connection capacity (e.g. 43 kW), then it must be ensured that the electric cars at the four charging stations do not all use the full 22 kW of power at the same time. Otherwise, the fuse will blow or, at worst, the power cable will overheat. The most common load management systems have different ways of recognising and preventing overloading:
1. Load management systems which are familiar to us detect overloading by directly measuring either the actual power or the number of electric cars connected.
2. Overloading is prevented in one of the following ways:
a) The available charging power is reduced for all charging stations and e.g. all charge with 16 A.
b) The number of electric cars that can be charged simultaneously is limited, e.g. two electric cars are charged until their batteries are full.
c) A mixture of these two strategies is used, e.g. when one electric car must be charged more quickly than another.