Electromagnetic Compatibility (EMC): Overview: Notes

Vehicles are typically subject to certain legal requirements that limit the amount of electromagnetic interference (EMI) that can be generated by the vehicles electronic devices. Additionally, the electronic devices within the vehicle must be able to withstand a certain amount of EMI without effecting their operation. EMI is generated whenever electrical current flows through a circuit. The amount of EMI generated, or amplitude, is usually dependant upon the amount of current flow, amperage, and the on-off pattern of current flow through the circuit, frequency. The EMI requirements are generally referred to as electromagnetic compatibility (EMC).

There are many ways of ensuring the vehicle meets EMC requirements. These include:

• Adding capacitors and resistors to certain electrical circuits
• Regulating the frequency at which a component may operate
• Shielding the wires, cables and components