What principle do electric vehicles use?

Who is allowed to use high voltage?

Because electrical current is in principle dangerous above a certain voltage, the legislator has defined hard limit values: AC voltage of more than 30 volts and DC voltage of more than 60 volts are considered high voltage and therefore dangerous. Even if the term high-voltage has nothing to do with the conventional terms used in house electrics, these 30 volts AC and 60 volts DC form the magical limit for everything that has to do with batteries, orange cables or electric drives in the workshop.

It is reassuring: for classic combustion engines with twelve-volt systems, commercial vehicles with 24 volts or mild hybrids with 48 volts - nothing changes. The voltage level of these on-board electrical systems is below the magical limit and may also be serviced and repaired in the future without additional HV qualification. Annoyingly, however, many manufacturers also equip their 48-volt hybrid systems with orange cables, so that such vehicles cannot easily be distinguished from real high-voltage vehicles. Only precise knowledge of the vehicle, the manufacturer's documentation or a look under the hood helps - high-voltage systems are marked as such with stickers.

In addition to defining the dangers, the legislature has also taken numerous measures to ensure that people do not kill themselves when using kettles, chainsaws or electric vehicles. The principle of risk minimization therefore always applies to the safety of machines, in which technical measures have priority over organizational measures or personal protective equipment. For this reason, the E-Golf, Kona or i-3 are designed to be intrinsically safe. Your high-voltage system is automatically de-energized if a fault occurs, the airbag is triggered or the ignition key is removed, for example.

legal framework

This voltage-free switching is the technical measure of the car product in order to keep the risk of an electrical accident as low as possible. The intrinsic safety of the systems not only protects the driver, but also the mechatronic engineer. In the workshop, the accident insurance guideline BGI / GUV-I 8686 applies as the legal framework - and with it it becomes complicated for the entrepreneur. After all, it is his job to ensure the safety of his employees. In times of high-voltage vehicles, he must therefore organizationally (and technically) minimize the potential dangers at this point. And since knowledge often protects against accidents, guideline 8686 basically describes three different levels of knowledge for employees who have to do with HV vehicles.

Step-by-step plan

The electrotechnically trained person EuP is at level one according to this definition. This EuP is practically the lowest level and can be reached after just two hours of instruction. Such an employee is allowed to maneuver Model 3, Hybrid-Jetta and ZOE in the yard, wash, change wheels or work on the twelve-volt system - but only after consultation with and only under the guidance of a certified level two expert. After all, someone must have ensured in advance that the vehicle also has the prescribed intrinsic safety.

The path to this certified specialist knowledge and thus to level two varies depending on the initial qualification, but is at least 16 lessons. An employee qualified in this way can now do all sorts of things: He can accept and assess an HV vehicle, determine or establish the absence of voltage, and delegate and supervise work on the voltage-free HV system. In the VW Group, such specialists are called high-voltage technicians.

However, if vehicles can no longer be disconnected from the power supply, the qualification of this level two ends - for work on components that are live, a qualification according to level three is required. It certifies certified specialist knowledge for work on non-HV intrinsically safe vehicles as well as work while live and on HV energy storage devices. The way to this level is significantly longer and also depends on the initial qualification. In addition to training of at least 24 hours of instruction, employees must complete a G25 occupational health examination (driving, driving, monitoring activities) every three years and submit a first-aid certificate every two years. Only then are they allowed to open batteries or work on energized vehicles involved in accidents.

Training helps

In practice, there are some pitfalls here: For example, an employee with certified specialist knowledge can accept a vehicle with a defective HV compressor, determine that there is no voltage and delegate the work to an EuP. However, she actually has to supervise the work - and therefore is not allowed to work in the adjacent hall or be on vacation the following day if the work extends over two days. If there is an accident, she has violated her duty of supervision.

For the entrepreneur - analogous to the risk analysis - there are a number of obligations that go far beyond the simple purchase of rubber gloves and VDE tools. Because HV vehicles will appear more and more in the future, training at this point is always worthwhile. Ideally, you should not only qualify one, but several employees at the same time.

Jens Meyer

With friendly support from

TRAINMOBILE
Training for Praktiker GmbH, Hamburg
www.trainmobil.de | [email protected]
Contact person: Elmar Wenzel, Tel. 040 897 206-100

The Trainmobil training program covers all workshop areas - from electronics and technology to sales and management. With the help of 3-D models, even complex technology can be easily understood.