International English | Electromagnetic Compatibility |
6 Electromagnetic Compatibility (EMC)
6.1What is EMC?
All electronic and electrical equipment generate unwanted signals. These signals can be emitted from the product either via cables that are connected to the product (Input, output, signal etc.) or via electromagnetic radiation ‘radio transmission’. These signals can be received by other products (via the same routes) and can interfere with the correct operation of the product.
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Emissions: Conducted and Radiated | Immunity: Conducted and Radiated |
Figure
Any particular product gives out a certain level of emissions, and has a certain level of immunity to incoming signals from other products. If the immunity of all products is higher than their emissions, all is well. If this is not the case, severe problems can occur, causing quality problems, damage, or in extreme cases injury.
Electromagnetic Compatibility concerns how equipment works together. Electromagnetic Interference (EMI) refers to the unwanted signals themselves.
EMI has become a more serious problem recently as more electronic systems (which may prove to have low immunity) are used in industrial applications, and as power electronic products such as drives, generate high frequency signals which can produce high levels of interference.
6.2Minimising the problem of EMI
EMI and EMC are much better understood than a few years ago, and most manufacturers of electronic equipment take care during design and installation to minimize emissions and maximize immunity. Siemens inverters are carefully designed with this in mind, and optional filters can be specified (either built in or as an external option) to reduce the emissions in the supply.
Before describing the practical solutions to EMI, it is important to understand the practical problems associated with EMC and inverters.
MICROMASTER Applications Handbook | 29 |