Installation
16
EMC guidelines
The following guidelines are intended to help vehicle manufacturers to meet the requirements for
Electromagnetic Compatibility. Any high speed switch is capable of generating harmonics at frequencies
that are many multiples of its basic operating frequency. It is the objective of a good installation to
minimise, contain or absorb the resultant emissions. All wiring is capable of acting as a receiving or
transmitting antenna. Arrange wiring to take maximum advantage of the structural metal work inherent
in most vehicles. Link vehicle metalwork with conductive braids.
General measures
Power cables
Use shielded power cable for all connections to the motor and the battery. Where cables pass through
metal enclosures, such as at the motor and battery; use metal cable glands to connect the cable shield to
the enclosure, ensuring that the various enclosures are linked with conductive braid to the vehicle
chassis.
Route all cable within the vehicle framework and keep as low in the structure as is practical - a cable run
within a main chassis member is better shielded from the environment than one routed through or
adjacent to an overhead guard. Keep cables short to minimize emitting and receiving surfaces. Shielding
by the structure may not always be sufficient - cables run through metal shrouds may be required to
contain emissions.
Parallel runs of cables in common circuits can serve to cancel emissions - the battery positive and
negative cables following similar paths is an example. Tie all cables into a fixed layout and do not deviate
from the approved layout in production vehicles. A re-routed battery cable could negate any approvals
obtained.
The cable manufacturers’ recommendations for minimum bend radius should always be followed.
Good practice when routing cables is to keep power cables at least 300mm from the signal cables.
Signal cables
Keep all wiring harnesses short and route wiring close to vehicle metalwork. Keep all signal wires clear
of power cables and consider the use of shielded cable. Keep control wiring clear of power cables when
carrying analogue information - for example, accelerator wiring and speed feedback. Tie all wiring
securely and ensure it always follows the same layout.
Measures required for specific signals
High voltage battery/generator power cables
Cables should be as short as possible. Minimise the loop area of the B+ and B- wiring. A common mode
ferrite choke may be required. Shielded cables may be required in some applications.
Motor power cables
Cables should be as short as possible. Minimise the loop area of the M1 M2 M3 wiring. A common mode
ferrite choke may be required. Shielded cables may be required in some applications.
Motor encoder connection, types AB, UVW, Sin-Cos and Resolver
• The encoder cable must be as short as possible.
• A multi-core shielded cable should be used.
• The inner cores should be used for the encoder supply and encoder ground and the AB or UVW or
Sin-Cos signals.
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