UNECE R10 is the regulation governing the electromagnetic compatibility of motor vehicles and the electrical/electronic sub-assemblies fitted to them. Its official title is "Electromagnetic compatibility", and it is published among the annexes of the 1958 Geneva Agreement.
Two separate approval routes
There are two types of approval under R10. The first is whole vehicle approval: the vehicle as a whole is measured in a semi-anechoic chamber. The second is electrical/electronic sub-assembly (ESA) approval: a single control unit or module is approved on its own. Electronic equipment fitted after sale is also approved as an ESA.
The four headings measured
| Heading | What is examined? |
|---|---|
| Radiated emission | The electromagnetic interference radiated into the air by the vehicle or sub-assembly |
| Conducted emission | Interference propagated over supply and signal lines |
| Radiated immunity | Continuation of function under an external electromagnetic field |
| Conducted immunity | Resistance to disturbing signals arriving over lines |
Additional scope for electric vehicles
The more recent series of amendments to R10 also cover behaviour in charging mode for electric and hybrid vehicles. While the vehicle is connected to the supply network, both the interference it emits and its immunity to disturbances coming from the network are assessed. The on-board charger and the charging cable set are part of this scope.
Frequency ranges, field strength levels and limit curves are defined in the annexes of the series of amendments in force and vary with the vehicle class. This page gives no numerical levels; the values must be taken from the edition in force at the date of application.
Frequently encountered problems
- The wiring harness arrangement during the test differing from that in the actual vehicle — the result loses its representativeness.
- Switched-mode power supplies exceeding the conducted emission limits.
- The functions to be monitored during immunity testing not having been defined in advance.
- Equipment fitted after sale not having its own ESA approval.
- A software update changing EMC behaviour and this not being notified.
Who grants the approval?
The laboratory carries out the test and issues its report; type approval is granted by the approval authority of a country party to the 1958 Agreement. The laboratory submits its report to that authority as a technical service. A test report alone is not a type approval certificate.
Why does the general EMC directive not apply to vehicles?
For electromagnetic compatibility, vehicles and vehicle components are subject not to general product legislation but to the vehicle type approval system's own regulation. The reason is not an arbitrary legal preference but that the electromagnetic environment of a vehicle is distinctive: circuits switching high currents, sensitive sensors, radio receivers and safety-critical control units all sit within the same body.
The test arrangements are therefore different too. While general EMC tests are carried out in set-ups representing a benchtop device, on the vehicle side separate arrangements are defined both for the WHOLE VEHICLE and for individual electronic sub-assemblies. The vehicle itself behaves like an antenna and the body geometry affects the result.
Two separate levels of approval
| Level | What is assessed |
|---|---|
| Whole vehicle | The interference the vehicle emits and its immunity to external fields; the vehicle's own geometry and wiring installation are included in the assessment. |
| Electronic sub-assembly | The emission and immunity behaviour of a single control unit, driver or module; approval is granted at component level. |
In practice this duality means: using an approved sub-assembly does not secure the vehicle's approval, and the vehicle's approval does not legitimise selling that component separately. Which party holds each level must be made clear in the supply chain by contract.
What did electric vehicles change?
- High-voltage power train components produce powerful switching noise not found in conventional vehicles; the burden on the emission side has risen markedly.
- During charging the vehicle is connected to the supply network; this makes the vehicle both a road vehicle and equipment connected to the network, and a separate assessment is required for the charging state.
- The sensors of driver assistance and autonomous functions are sensitive to electromagnetic interference; immunity is now a safety matter rather than one of comfort.
- Wireless charging and vehicle-to-grid communication bring new frequency bands into play and intersect with radio regulations.
What to look for when reading a report?
The decisive items in a vehicle electromagnetic compatibility report are: at which level the approval was granted (whole vehicle or sub-assembly), which operating modes the vehicle or unit was in during the test, which wiring harness and mounting arrangement were used, and how functional degradation was classified in the immunity tests. That last item is particularly important: in immunity testing some functional degradations are considered acceptable, while for safety-critical functions no degradation is accepted, and the report must state that distinction.
The country code within the approval number shows the authority that GRANTED the approval, not the geography in which it is valid. Through mutual recognition, the approval is accepted in the countries party to the agreement.