GB/T 18039.4-2017 Electromagnetic compatibility - Environment - Compatibility levels in industrial plants for low-frequency conducted disturbances
1 Scope
This part of GB/T18039 is about the conducted interferences in the frequency range of 0 - 9 kHz, and provides the compatibility levels of plants and non-public power supply system.
This part is applicable to AC 50 Hz low-voltage and medium-voltage power supply systems. This part does not cover the power supply systems of ships, planes, offshore platforms and railways.
The compatibility levels involved in this part may be used for the internal connection points (IPC) of plants. When the equipment is connected to the access point of the above power supply systems, the severity of interferences can be comparable to that of the internal connection points in most cases. In some cases, especially in the case of long-distance power supply to special loads, or when the interference between interference sources or internal equipment is amplified, its interference is different from that of internal connection points.
Compatibility levels are given according to different types of electromagnetic environment, and it is expected to guide the compatibility levels of connecting points in plants or other non-public power networks:
a) Set the limit of electromagnetic disturbances to industrial power network (including the planning level defined in 3.1.5);
Note 1: the electromagnetic environment of industrial power network and non-public power supply system may involve a wide range of cases, which are divided into three types in this part (see Clause 4).
However, the operators of such power networks need to consider special electromagnetic conditions, economic conditions and equipment characteristics when setting the above limits.
b) Select the immunity level of the equipment to the conducted disturbances of plants and non-public power supply systems.
Disturbances include:
- voltage deviation
- voltage sag and short-time interruption
- voltage unbalance
- power supply frequency deviation
- harmonic (50 times or below)
- interharmonics (50 times or below)
- high-frequency voltage component (frequency higher than 50 times of harmonic);
- transient overvoltage
- DC component
The compatibility of electromagnetic environment is divided into different levels based on the characteristics of power supply network.
Note 2: the PPC compatibility level of low-voltage public power network is defined by IEC 61000-2-2, and medium-voltage power network is defined by IEC 61000-2-12.
The technical reports of IEC 61000-3-6 and IEC 61000-3-7 describe how the power supply department gives the emission limits of devices and large loads.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
IEC 60050-101 International Electrotechnical Vocabulary (IEV) - Part 101 : Mathematics
IEC 60050-161 International Electrotechnical Vocabulary (IEV) - Chapter 161: Electromagnetic compatibility
IEC 60050-551 International Electrotechnical Vocabulary(IEV) - Part 551: Power electronics]
IEC 61000-2-2 Electromagnetic compatibility(EMC) - Part 2-2: Environment - Compatibility levels for low-frequency conducted disturbances and signalling in public low-voltage power supply systems
IEC 61000-2-12 Electromagnetic compatibility(EMC) - Part 2-12: Environment - Compatibility levels for low-frequency conducted disturbances and signalling in public medium-voltage power supply systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161, IEC 60050-101 and IEC 60050-551 and the following apply.
3.1 General terms
3.1.1
(electromagnetic) disturbance
any electromagnetic phenomenon that may degrade the performance of an electric device in its electromagnetic environment
[IEC 60050-161, Definition 161-01-05, modified]
3.1.2
disturbance level
magnitude or amplitude of electromagnetic disturbance measured and estimated by the method specified in the standard
[IEC 60050-161, Definition 161-03 -01, modified]
3.1.3
electromagnetic compatibility; EMC
ability of a device or system to work normally in its electromagnetic environment without causing unacceptable electromagnetic disturbance to anything in the environment
Note 1: electromagnetic compatibility is an environmental condition. For example, for each phenomenon, the level of disturbance emission is low enough and the level of immunity is high enough, so that all devices, equipment and systems can operate properly.
Note 2: only when the emission and immunity level are controlled, i.e., the immunity level of devices, equipment and systems at any location is higher than the disturbance level caused by emission accumulation of emission sources and other factors (such as circuit impedance) at that location, can electromagnetic compatibility be reached. Generally, the so-called compatibility means that the probability of deviating from the predetermined performance target is small enough (see Clause 4 of GB/Z 18039.5).
Note 3: For a certain disturbance environment, compatibility can be interpreted as considering a single disturbance.
Note 4: Electromagnetic compatibility is a term, which is also used to describe the research field in which devices, equipment and systems are subjected to adverse electromagnetic influences from each other or other electromagnetic phenomena.
[IEC 60050-161, Definition 161-01 -07]
3.1.4
(electromagnetic) compatibility level
electromagnetic disturbance level specified as the reference level to coordinate the emission limit and immunity limit in the specified electromagnetic environment
Note: conventionally, the compatibility level selected shall be such that the actual disturbance level has a very small probability to exceed it.
[IEC 60050-161, Definition 161-03-10, modified]
3.1.5
planning level
specific disturbance level in a specific environment used as a reference value for determining the emission limits of heavy loads and devices in order to coordinate the emission limits of heavy loads and devices with the limits applicable to all devices connected to the power supply system
Note: planning level is regional and can be used for power network planning and operation in areas concerned (see Annex A for more information)
3.1.6
point of common coupling; PCC
point in the power supply network that is electrically closest to a specific load, at which other loads have been connected or can be connected
[IEC 60050-161, Definition 161-07-15, modified]
3.1.7
in-plant point of coupling; IPC
point in the internal network of a system or device that is electrically closest to a specific load, at which other loads have been connected or can be connected
Note: IPC is usually the point to consider electromagnetic compatibility.
3.2 Definitions related to phenomenon
The following definitions related to harmonics are based on the analysis of system voltage or current through Discrete Fourier Transform (DFT). This is the practical application of Fourier transform, which is defined in IEV101-13-09. See Annex A.
Note: Fourier transform of time domain function, whether periodic or aperiodic, is a frequency domain function called time function spectrum (or spectrum for short). If the time function is periodic, the frequency harmonic is composed of discrete lines (or components), if it is aperiodic, the frequency spectrum contains continuous functions of all frequency components.
Other definitions related to harmonics or interharmonics are given in International Electrotechnical Terminology (EV) and other standards. Relevant definitions not used in this part will be discussed in Annex A.
3.2.1
fundamental frequency
frequency in the frequency spectrum obtained from the Fourier transform of the time domain function, and all frequencies in the frequency spectrum take this frequency as reference. For the purpose of this part, the fundamental frequency is the same as the power supply frequency.
[IEV 101-14-50, modified]
Note 1: In a periodic function, fundamental frequency is generally the same as that of function frequency (see A.1).
Note 2: In case of uncertainty, the auxiliary power supply rate shall refer to the number of poles and speed of the synchronous generator supplying power to the system.
Note 3: This definition may be used for any industrial power supply network, regardless of the supplied load (simple load, composite load, rotating machinery or other loads), even if the power network is fed by semiconductor converter devices.
3.2.2
fundamental component
component whose frequency is fundamental
3.2.3
harmonic frequency
frequency which is an integer multiple of fundamental frequency
The ratio of harmonic frequency to fundamental frequency is named harmonic order (recommended notation “h”)
3.2.4
harmonic component
any component with harmonic frequency, whose value is usually expressed in r.m.s.
Simply put, this component can be called harmonic for short.
3.2.5
interharmonic frequency
frequency which is a non-integer multiple of any fundamental frequency
