Electromagnetic compatibility of variable frequenc

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Electromagnetic compatibility (EMC) of variable frequency drives in industrial applications is the ability of electrical/electronic equipment to operate without electromagnetic interference (EMI) in its installation environment. Electromagnetic interference refers to the interference that affects the operation of equipment due to irregular energy entering the equipment through the connection of lines or electromagnetic radiation. Electromagnetic interference caused by radiation, also known as radio frequency interference (RFI). Electromagnetic interference caused by conduction is the so-called high-frequency noise

American specifications and standards

in the United States, there are no specifications and standards that specifically and completely cover the electromagnetic compatibility of variable frequency drives (afds)

FCC Standard

Part 15 of the Federal Communications Commission (FCC) standard applies to unauthorized equipment that radiates radio frequency energy. FCC Part 15 applies to all variable frequency drives because they are radiation prone devices. All equipment covered by Part 15 must be operated under the general operating conditions listed in article 15.5. The purpose of article 15.5 is to require that the equipment shall not interfere with any legally operated broadcasting, navigation or security services, and must accept any interference caused by other equipment. According to article 15.13, manufacturers of radiation prone equipment shall adopt good engineering practices to minimize the risk of harmful interference

fcc15 is applicable to variable frequency drives controlled by microprocessors, because it belongs to digital devices. As a commercial or industrial equipment, variable frequency drive is a special case, which is only applicable to the general operating conditions specified in article 15.5 (above). Nevertheless, the Federal Communications Commission strongly recommends that manufacturers of these special equipment should strive to meet the technical standards of fcc15

fcc15 limits the radio frequency voltage transmitted from digital equipment to utility power lines, with a frequency range of 0.15 to 30 MHz. Fcc15 also limits the magnetic field intensity radiated by digital devices, with a frequency range of 30 MHz and above. The voltage transmitted to the power line below the frequency specified by FCC is regarded as harmonic distortion voltage. Harmonic distortion is defined in ieee519 standard

evaluate the driver as a digital device in fcc15

the microprocessor of the driver is unlikely to be an important source of electromagnetic interference. The most important potential source of electromagnetic interference and radio frequency interference is the power switching circuit. This potential source is largely independent of the design of microprocessors or other types of control circuits. The electromagnetic interference generated in the equipment is caused by the AC output waveform formed at the output end of the positive and negative conversion of the DC bus. With each output switch operation, the terminal voltage (for a 480 volt driver) jumps from 650 volts on one pole to 650 volts on the opposite pole. This instantaneous voltage change may produce a large amount of radio frequency energy

when the driver is evaluated as a digital device controlled by a microprocessor, it is not the most important source of electromagnetic interference

looking for drivers that meet the FCC standard

because the application regulations are not very clear and strict, almost all drivers that do not have electromagnetic filtering function are called to meet the fcc15 standard

the driver must meet the requirements of fcc15 for the transmission and radiation standards of class A or class B digital equipment, but fcc15 does not contain or describe the test methods designed for the driver. Since the corresponding test method is not described, any statement that the driver meets the specified standards is questionable

fcc15 standard on transmitted radiation was revised in 2002 to coordinate domestic needs to comply with the International Standard Committee - International Special Committee on radio interference (CISPR) (see FCC) formulated by the International Electrotechnical Commission (IEC)

The cispr11 standard provides a method to test whether the driver conforms to these standards

cispr12 has a lower radiation standard than fcc15. Therefore, fcc15.109 was added to fcc15 in 2003

optional radiation standards mentioned in sections a and B of this part, digital equipment should comply with CISPR with a national perspective 22 (1997) (see fccda)

cispr22 is for digital devices, while cispr11 covers industrial science and medical devices. The US Food and Drug Administration encourages manufacturers of medical electronic equipment to adopt cispr11. It needs to reduce the use by 25% by 2025

the European Commission instructed

in the European Economic Community, the European Commission formulates different standards for various products. Many of them come from IEC standards. The EMC product standard EN (or IEC) of electric drive system is the main standard of variable speed drive. The test method of this standard includes the test process and details, which is particularly suitable for drives, and this standard is quite comprehensive. It includes electromagnetic radiation and radiation immunity of the driver

two installation environments defined by IEC

the first environment

the first environment includes residential buildings. It also includes facilities that are not directly connected to the low-voltage power supply network that supplies power to residential buildings through an intermediate transformer

the second environment

the second environment includes all facilities except those directly connected to the low-voltage power supply that supplies power to residential buildings

iec makes sales plans for two kinds of users

unlimited sales

unlimited sales refers to a sales mode in which the supply of equipment does not depend on the EMC capability of customers or users

restricted sales

restricted sales refers to the sales mode in which manufacturers restrict the supply of equipment to suppliers, customers or users who have technical capabilities in electromagnetic compatibility of equipment. You must follow the instructions in the installation manual to install the drive

other information

other information can be found in two ABB publications:

- Technical Guide No. 2, European Commission Directive requirements and variable speed electric drive systems

- Technical Guide No. 3, The installation and configuration of EMC in the electric drive system

it is recommended that the drive with the most comprehensive electromagnetic compatibility should meet the requirements of iec-1 as hard materials, select a smaller speed to carry out the EMC standards and radiation standards of the experimenter's Committee, restrict sales and install in the first environment. Instructions for installing the drive must be included in the manual in order to comply with radiation standards. In terms of hardware, according to Article 6.3 of the national standard gb/t2611 (2) 007 general technical requirements for laboratory machines, it has been clearly stated that electrical equipment should have the ability to protect personal safety and avoid electric shock, which has been specified in detail.

drivers that meet the above provisions will generally meet the technical requirements of fcc15, including the radiation standard of class a digital equipment

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