A Guide to Electromagnetic Compatibility (EMC)

1 Electromagnetic COMPATIBILITYA Guide TO Electromagnetic Compatibility FOR VARIABLE SPEED DRIVES2 Electromagnetic COMPATIBILITYPURPOSE OF THIS GUIDEThis Guide is one of a series covering subjects such as harmonics, safety features, EMC, feedback devices, industrial communications and motion control. These can be accessed via of this Guide 21 . Introduction 4 General 4 Principles of EMC

2 4 EMC Regulations 52 . Regulations ans standards 5 Regulations and their application to drive modules 5 Standards 63.

3 EMC behaviour of variable speed drives 7 Immunity 7 Low frequency emission 7 High frequency emission 84.

4 Installation rules 10 EMC risk assessment 10 Basic rules 10 Simple precautions and fixes 13 Full precautions 145.

5 Theoretical background 15 Emission modes 15 Principles of input filters 18 Shielded motor cables 18 Ferrite ring suppressors 19 Filter ground leakage current 19 Filter magnetic saturation

6 19 Types of shielded motor cable 196 . Additional guidance on cable shielding for sensitive circuits 20 Cable shielding action 20 Cable shield connections

7 21 Recommended cable arrangements 237. Further Reading 244 Electromagnetic COMPATIBILITY1. GENERALThe purpose of this Guide is to set out the necessary considerations for system designersand others when incorporating electronic variable speed drives into complete machines and systems without encountering problems with Electromagnetic interference, and in compliance with relevant regulations.

8 Due to the wide variety of practical drive installations this Guide can only give general guidance. The underlying principles are explained as far as possible, to enable the designer to apply the Guide to a range of specific PRINCIPLES OF EMCAll electrical equipment generates some degree of Electromagnetic emission as a side effect of its operation. It also has the potential to be affected by incident Electromagnetic energy. Equipment using radio communication contains intentional emitters and sensitive basic principle of EMC is that Electromagnetic emission of electrical equipment, whether intentional or unintentional, must not exceed the immunity of associated equipment.

9 This means that controls must be in place on both emission and immunity. Given the variety and uncertainty of effects and situations, some margin of safety must be provided between these two all equipment exhibits some degree of emission and susceptibility, the limitingfactors in most common environments tend to be related to radio equipment, with itspowerful transmitters and sensitive receivers. Therefore the majority of EMC standardsare related to the requirements of radio communications principle, EMC covers phenomena over an unlimited range of frequencies and wavelengths.

10 The EU EMC Directive limits itself to a range of 0 to 400 GHz. This range is so wide that a perplexing number of different effects can occur, and there is a risk that all electrical phenomena become included in the scope of EMC. This is also the reason for the proliferation of EMC rules of thumb , some of which are contradictory. A technique which is effective at a high radio frequency will probably not be effective at power frequency, and current industrial electronic techniques, it is unlikely that equipment will exhibitunintentional sensitivity or emission above about 2 GHz.