Brief Introduction to EMC
The concern of designers to product electromagnetic compatibility issues has dramatically increased in the recent years. Many different standards have been developed and released, and all electrical and electronics engineers are aware of different compatibility tests.
Unfortunately, there are still a lot of designers that encounter difficulties when dealing with EMC, either with understanding the issue, or in solving the related problems.
So, what is EMC?
ElectroMagnetic Compatibility (EMC) is defined as the ability of a device or system to satisfactorily function (without errors) in the target electromagnetic environmental conditions.
Nowadays, various EMC standards define the permissible electromagnetic interaction between every system and its immediate environment. All electronic systems must be compatible to all other systems in the affected environment, in terms of EMC. This system compatibility must be proven by tests to be certified by the applicable EMC standard.
All these developments had lead to the emergence of a new engineering branch – the EMC engineering.
EMC engineering use analytical methods, design practices, test procedures, and solution hardware and components both to enable the system to function without errors in its target electromagnetic environment, and to prevent it from inflicting errors to any adjacent system. It also enables the system to meet the EMC control specifications limits.
EMC deals with 3 major components:
· The source of interference (noisy system or power supply), also called EMI source.
· The victim of interference (sensitive circuitry), also called EMI victim
· The coupling path.
EMI (Electromagnetic Interference) is defined as the electromagnetic emissions discharged by a device or a system that interfere with the normal operation of other devices or systems.
Electromagnetic compatibility problems are generally solved by identifying at least two of the above mentioned components and eliminating one of them.
Potential sources of electromagnetic compatibility problems include radio transmitters, power lines, electronic circuits, lightnings, lamp dimmers, electric motors, arc welders, solar flares and just about everything that utilizes or creates electromagnetic energy.
Potential receptors include radio receivers, electronic circuits, appliances, people, and just about everything that utilizes or can detect electromagnetic energy. The way this electromagnetic energy is transferred from a source to a receptor fall into one of the following four categories.
1. Conductance (electric current)
2. Inductive coupling (magnetic field)
3. Capacitive coupling (electric field)
4. Radiation (electromagnetic field)
The coupling paths are often comprised of a complex combination of these routes, making the path difficult to be identified, even when the source and/or receptor are known. There may be multiple coupling paths, and steps taken to attenuate one may enhance another.
· Conducted noise is coupled between components through interconnecting wires such as power supply and ground lines. Common impedance coupling is caused when currents from two or more circuits flow through the same impedance such as power supply and ground lines.
· Radiated electromagnetic field coupling can be handled in one of the following ways: in the near field, E and H field couplings are handled separately. In the far field, the coupling is handled as a plane wave coupling.
· Electric field coupling is caused by the voltage difference between conductors. The coupling mechanism can be modeled by a capacitor.
· Magnetic field coupling is caused by the current flow in conductors. The coupling mechanism can be modeled by a transformer.
The most common methods used for noise reduction include proper circuit design, shielding, grounding, filtering, isolation, separation and orientation, circuit impedance match control, cable design, and other noise cancellation techniques.
RF Immunity gained extensive experience in developing and producing filter and transient protection connectors. We have a variety of off the shelf connectors similar in size to standard connectors, and we have the capacity to develop custom made filtering products that are fully compatible with the customer specifications and enable the customer system to be approved by compatibility tests.