Emc Guidelines - Sevcon MillipaK 4QPM Manual

EMC Guidelines

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EMC Guidelines
The following guidelines are intended to help vehicle manufacturers to meet the requirements of
the EC directive 89/336/EEC 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 contain or absorb the
resultant emissions.
All wiring is capable of acting as a receiving or transmitting antenna. Wiring should be arranged
to take maximum advantage of the structural metal work inherent in most vehicles. Vehicle
metalwork should be electrically linked with conductive braids.
Power Cables
All cables should be routed within the vehicle framework and kept as low in the structure as is
practical - a cable run within a main chassis member is better screened from the environment than
one routed through or adjacent to an overhead guard.
Power cables should be kept 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.
Signal Cables
All wiring harnesses should be kept short.
Wiring should be routed close to vehicle metalwork.
All signal wires should be kept clear of power cables or made from screened cable
Control wiring should be kept clear of power cables when it carries analogue information - for
example, accelerator wiring.
Tie all wiring securely and ensure wiring always follows the same layout.
Controller
Thermal and EMC (emissive) requirements tend to be in opposition.
Additional insulation between the controller assembly and the vehicle framework reduce
capacitive coupling and hence emissions but tend to reduce thermal ratings. A working balance
needs to be established by experiment.
The complete installation should be documented, in detail, and faithfully reproduced on all
production vehicles. When making changes, consider their effect on compliance ahead of any
consideration of cost reduction or other "improvement".
MillipaK 4QPM Controller Manual Page 72 13/08/03