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Specification of high-performance vector convertor
Chapter 7 EMC (Electromagnetic compatibility)
7.1 Definition
Electromagnetic compatibility means that electrical equipment operates under environment of
electromagnetic interference, but it does not interfere electromagnetic environment and realizes the
function stably.
7.2 Introduction of EMC standard
According to requirements of national standard GB/T12668.3, frequency convertor shall conform to
requirements of two aspects: electromagnetic interference and anti-electromagnetic interference.
Our current products execute latest international standards: IEC/EN61800-3: 2004 (Adjustable speed
electrical power drive systems part 3: EMC requirements and specific test methods), which is equal to
national standard GB/T12668.3.
IEC/EN61800-3 mainly checks frequency convertor from two aspects: electromagnetic interference
and anti-electromagnetic interference. Electromagnetic interference mainly tests radiated interference,
conducted interference and harmonic interference of frequency convertor (requirements on the frequency
convertor for civil use). Anti-electromagnetic interference mainly tests conduction immunity, radiated
immunity, surge immunity, fast changed pulse group, ESD immunity and immunity of low-frequency
terminal of power (specific test items include: 1. immunity test for input voltage sag, interruption and
change; 2. immunity test for commutation notch; 3. immunity test for harmonic input; 4. change test for
input frequency; 5. unbalance test for input voltage; 6. fluctuation test for input voltage). The test is
conducted as per strict requirements of above IEC/EN61800-3, and please install our company products as
per instructions of 7.3, which own good electromagnetic compatibility under general industry environment.
7.3 EMC guidance
7.3.1 Influence of harmonic: higher harmonic of power will damage frequency convertor, so it's suggested
to install AC input reactor in the places with weak quality of power grid.
7.3.2 Electromagnetic interference and installing precautions: there are two kinds of electromagnetic
interference. One is interference of surrounding electromagnetic noise for frequency convertor, and
another is interference produced by frequency convertor for peripheral equipment.
Installing precautions:
1) Earthing wire of frequency convertor and other electrical products should be well grounded;
2) Do not layout power input and output line or weak current signal line (e.g. control circuit) of
frequency convertor in parallel, layout them vertically if possible;
3) It's suggested to use shield cable or steel tube shield power line for output power line of
frequency convertor, and keep reliable earthing of shield layer. For the lead of equipment with
interference, it's suggested to use dual twisted pair shield control line and keep reliable earthing of
shield layer;
4) For the motor cable exceeding 100m, output filter or electric reactor should be installed.
7.3.3 Handling method of interference produced by peripheral electromagnetic equipment for frequency
convertor: in general, the cause of frequency convertor produces electromagnetic influence is that
many relays, contactors or electromagnetic brakes are installed nearby frequency convertor. If any
malfunction of frequency convertor due to interference, it's suggested to adopt below methods:
1) The devices producing interference are installed with surge suppressor;
2) Install filter in input terminal of frequency convertor as per 7.3.6 for operation;
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EMC
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