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Brief Introduction of Electromagnetic Compatibility Test for Rail Transit
Release time:
2023-08-14 15:44
Source:
1. Overview
1, the foreword
With the process of urbanization in China, rail transit, as an efficient, safe and large capacity mode of urban transportation, is more and more adopted by major cities.
Along with this, the degree of electrification of rail transit system is getting higher and higher. In addition to the equipment and pipeline system necessary for normal operation, the electronic equipment and various signal interfaces in the system are becoming more and more complex.
Some equipment/devices in operation will produce strong electromagnetic interference to the outside world, such as train overhead traction catenary, pantograph, mobile communication device, etc.; some equipment is more sensitive to electromagnetic interference, such as control system, weak current system, etc.
2, the standard status quo
At present, the influential international standards for electromagnetic compatibility of rail transit mainly include EN50121 series and IEC62236 series.
The EN 50121 series is the current European electromagnetic compatibility standard for railway facilities and the world's first complete electromagnetic compatibility standard system for rail transit. It not only provides a set of electromagnetic compatibility management framework for the railway system, but also stipulates the electromagnetic emission limits of the railway system as a whole and the electromagnetic emission and immunity test limits of the equipment operating in the system, a total of 6 parts.
The original version of the EN50121 series of standards was promulgated by the European Electrotechnical Standardization Committee (CENELEC) in 1996, revised in 2000 and 2006 respectively, and corrected once in 2008. At present, the latest electromagnetic compatibility standard version is EN50121: 2015.
The IEC62236 was originally revised in 2003 and adopted the EN50121: 2000 version of the standard. Its structure and content are basically the same as the EN50121. The current IEC62236 version is in 2018.
Before the promulgation of GB/T 24338 series, China's railway system did not have a complete electromagnetic compatibility standard system. The main electromagnetic compatibility standards were TB/T 3034 and TB/T 3073. These two standards respectively stipulate the electrical equipment of rolling stock, namely on-board electrical equipment, electromagnetic compatibility test items test level and emission limit, and railway signal equipment, namely ground signal equipment, electromagnetic compatibility test items, test level and emission limit.
GB/T 24338 specifies the electromagnetic emission limits and measurement methods of the entire rail system to the external environment, as well as the electromagnetic emission limits, immunity levels, performance criteria and measurement methods of rail transit equipment.
The applicable frequency range of GB/T 24338 (all parts) is 0 GH ~ 400 GH, and the test is not carried out at the frequency without requirements. The static emission limit requirements for trunk railways, subways and trolleybuses are different.
3,GB/T 24338 standard
GB/T24338 "Rail Transit Electromagnetic Compatibility" currently includes the following parts:
GB/T24338.1-2018 Rail Transit Electromagnetic Compatibility Part 1 General
GB/T24338.2-2018-Electromagnetic compatibility for rail transit-Part 2: Launch of the entire rail system to the outside world
GB/T24338.3-2018 Rail Traffic-Electromagnetic Compatibility-Part 3-1: Rolling Stock-Trains and Complete Vehicles
GB/T24338.4-2018 Rail Transit-Electromagnetic Compatibility-Part 3-2: Rolling Stock Equipment
GB/T 24338.5-2018 Rail Transit-Electromagnetic Compatibility-Part 4: Emission and Immunity of Signaling and Communication Equipment
GB/T 24338.6-2018 Rail Transit-Electromagnetic Compatibility-Part 5: Emission and Immunity of Ground-powered Equipment and Systems
The test items of electromagnetic compatibility of rail transit are similar to those of general civilian products, including:
Electromagnetic compatibility emission EMI test: conducted disturbance test, radiation disturbance test.
Electromagnetic compatibility immunity EMS test: electrostatic discharge test, radio frequency electromagnetic field radiation immunity test, pulse group test, surge impact test, conducted immunity test, power frequency magnetic field test, pulse magnetic field test.
The difficulty of the test lies in:
1) There are many types of power supply configuration and complex sources of harassment;
For trains powered by 380VAC power supply system, the power supply generally comes from the diesel generator of the power generation compartment in the train formation; The power supply voltage of the high-speed railway is 27.5KV, and the electricity is supplied to the train through the catenary via the pantograph. After the high-voltage electricity is transmitted to the auxiliary converter, 440VAC voltage is output, and then the voltage is adjusted to the voltage required by each equipment through the transformer, such as 220VAC; Some models have added inverter equipment, which can boost and invert the electricity in the battery at the bottom of the train into AC220V and supply it to the socket.
Figure 1
2) There are many types of power systems and subsystems, and the power changes greatly;
The rail transit system mainly includes EMU, power supply system, braking system, communication system and control system.
The EMU is the core part of the high-speed rail, which is responsible for driving the high-speed rail forward. The EMU usually consists of a group of electric locomotives and a group of power cars, in which the electric locomotives are responsible for generating electricity and the power cars are responsible for transmitting power.
The power supply system is an important part of the power system and is responsible for providing power to the train.
The braking system is an important part of the power system, which is responsible for controlling the speed of the train and stopping safely.
The communication system is an important part of the high-speed rail power system, which is responsible for the information transmission and interaction of the high-speed rail.
The control system is an important part of the rail transit system, which is responsible for controlling the operation of the train. The control system usually uses a combination of computer control and manual intervention. The general-speed railway is mainly controlled by people and assisted by machines, while the high-speed railway uses a CTCS-3-level international advanced train control system, which is the reverse-machine control is mainly controlled and people are assisted.
Fig.2 Principle block diagram of C3 system
3) The environment in which the vehicle operates is complex;
The railway line is long, mountains, plateaus, plains, deserts, cities, villages, and many other factors cause the railway electromagnetic environment to be complex and changeable. The minimum travel interval of high-speed railway is 3 minutes. Under such high-speed and high-density traffic, it is important and necessary to ensure the safety of vehicle operation.
Figure 3
4) The power fluctuation of the train is difficult to control;
The main interference sources of high-speed railway are traction equipment and pantograph-catenary electric sparks. The viaduct of high-speed railway and the car body of high-speed train will also block and reflect the radio signal, which will adversely affect the propagation of various radio signals. If a high-speed motor car with a speed of 350 kilometers per hour brakes instantly, it needs to slow down and coast for 6500 meters. The fluctuation of train power supply caused by various factors is irregular and difficult to control. The high-speed rail must comply with the "high reliability, high availability, and high safety principles". When the system detects any factors that may affect the safe operation of the train, the train control system will automatically take measures to prevent serious consequences in time.
Figure 4
4, the necessity of electromagnetic compatibility design
In such an extremely complex and sophisticated system, once a certain device is affected by electromagnetic interference and cannot work normally, or even malfunction, it will bring very serious consequences to the rail transit system. Therefore, we need to have a comprehensive understanding of the relevant electromagnetic compatibility standards. At the beginning of designing and manufacturing rail transit electronic products, we should:
1) Ensure that the rail transit system equipment/devices will not generate electromagnetic interference exceeding the standard limit level, so as to avoid interference to other electronic and electrical equipment with weak immunity;
2) Ensure that the rail transit system equipment/devices have certain anti-interference ability;
3). Ensure that the rail transit system equipment/devices meet the relevant national electromagnetic compatibility requirements;
4). Ensure that the rail transit system equipment/devices meet the electromagnetic compatibility requirements in the specification requirements of the rail vehicle owner's customer;
In every link from design to mass production, quality control should be carried out on vehicles and parts suppliers, and they should be required to increase the intensity and reading of electromagnetic compatibility tests in order to reduce the occurrence of electromagnetic compatibility problems. Ensure that all electrical and electronic products can operate normally in various electromagnetic interference environments without interfering with other systems. To protect the safety and operational efficiency of public transport equipment as much as possible, and to protect the safety of people's lives and property.
2. the launch of the entire orbital system to the outside world
GB/T 24338-2 specifies the limits and measurement methods for the external emission of the entire rail system (including urban rail transit system). The scope of application of GB/T 24338-2 does not include the entire underground rail system and the launch does not affect the ground.
1, basic measurement parameters
Figure 5
The measuring distance between the measuring antenna and the center line of the track on which the rolling stock is running shall be 10 m.
If the center of the track is less than 30m from the nearest Traction Substation Fence (Enclosure), measurements shall only be made on the other three fences (Enclosure); otherwise, measurements shall be made on the four fences (Enclosure).
If the side length of the fence (fence) exceeds 30 m, measuring points shall be added at the corners of the fence (fence). If the traction substation does not have a fence (fence), the measuring antenna shall be 10 m away from the equipment or its housing.
Figure 6 The height of the center of the loop antenna from the reference plane should be selected from 1.0m to 2.0 m.
Figure 7 The height of the center of the dipole antenna or the logarithmic periodic day from the reference plane should be selected between 2.5 m and 3.5m.
The measurement report shall record the selected height.
The ambient noise shall be recorded at the beginning and end of the test.
2, Test methods and limits
1) For rolling stock in operation:
The launch of the system is mainly from the launch of the contact network, rather than the launch of the rolling stock itself. It is therefore only necessary to carry out the measurement on the rolling stock side. For a three-rail current receiving system, the measuring point shall be on the same side as the third rail.
Peak detection is used for measurement, and the dwell time of the selected frequency point shall be long enough to ensure accurate measurement results, which should be 50ms.
When the rolling stock passes the measuring point, the system emission is not necessarily the maximum, but may be the maximum when the rolling stock passes a position far away from the measuring point. Therefore, the measurement time should be long enough to ensure that the maximum system emission is measured.
For overhead track measurement, if the aforementioned antenna height requirements cannot be achieved, the ground plane can be used instead of the rail plane as the reference plane for the antenna height. The train shall be within the visual range of the measuring point, and the extending direction of the central axis of the antenna shall point to the train. The measuring point should be 30m away from the center line of the track. The measurement report shall detail the measurement arrangement.
If the object of measurement is a railway system with overhead catenary, the measuring point shall be selected at the midpoint of the two pillars of the overhead catenary and not at the discontinuous point of the contact conductor. During the measurement, it should be confirmed whether there is a resonance point in the radio frequency range. If there is a resonance point, the measurement frequency should avoid the resonance point, and the resonance point should be recorded in the measurement report.
8 Emission limits from 0.15 MHz to 1GHz (10m method)
Description:
A limit curve-applicable to AC 25 kV power supply line;
B limit curve-applicable to AC 15 kV, DC 3kV and 1.5kV power supply lines;
C limit curve-suitable for urban rolling stock and non-electrified lines such as 750V and 600V DC supply lines
2) For traction substation:
The emission measurement shall be carried out under the specific feed structure layout conditions of the rail transit traction power supply system. The load of rail transit substation changes in a wide range in a short time, and the load directly affects the electromagnetic emission, so the actual load change should be recorded in the measurement.
The peak detection maximum hold scan shall be used for measurement. If a frequency component exceeding the limit is found, the quasi-peak detection measurement shall be carried out for the frequency component. The load conditions measured by quasi-peak detection need not be accurately reproduced, but should be comparable, compared with the load conditions at the time of peak detection.
Fig. 9 Emission Limit of Traction Substation (Quasi-Peak)
The limits in Figure 9 correspond to the following bandwidths defined in GB/T 6113.101:
-9 kHz bandwidth for 0.15 MHz ~ 30 MHz measurement;
-120 kHz bandwidth for measurement from 30 MHz to 1GHz;
Figure 9 limits also apply to other ground fixtures such as autotransformers
3, data measurement method
The electromagnetic emission generated by the track system (including the rolling stock in operation) shall be measured by the fixed frequency method or the frequency scanning method according to the train operation mode and speed, and the following requirements shall be met:
-- The measuring instrument shall meet the requirements of GB/T 6113.101
-If the rolling stock is running at high speed, the fixed frequency method shall be adopted to continuously monitor each frequency point. If the scanning rate meets the requirements of the following table, the scanning time for the mobile emission source is short enough to ensure that the train can complete a scan every 5m, and the frequency scanning method can be used as an alternative method. At higher speeds, the FFT technique is superior to the frequency sweep approach.
-- When the rolling stock is running at the maximum rated power and the speed is slow, the frequency scanning method can be used.
Figure 10
Testing of 3. rolling stock
Rolling stock is divided into two parts:
GB/T24338.3-2018 Rail Traffic-Electromagnetic Compatibility-Part 3-1: Rolling Stock-Trains and Complete Vehicles
GB/T24338.4-2018 Rail Transit-Electromagnetic Compatibility-Part 3-2: Rolling Stock Equipment
GB/T24338.3 specifies the emission and immunity requirements for all types of rolling stock (including towing vehicles, trailers and urban vehicles used in urban streets), but it should be noted that GB/T24338.3 does not specify the vehicle immunity test!
If it is confirmed through the electromagnetic compatibility management plan that all equipment meets the immunity limit requirements of GB/T 24338.4, the immunity of the vehicle with integrated equipment meets the requirements.
1. Test conditions for radio frequency electromagnetic disturbance of train and vehicle:
The test shall cover all operating modes of on-board equipment that may generate electromagnetic emissions.
The trailer shall be tested under static live operating conditions (normal operation of auxiliary converter, battery charger, etc.). The antenna should be aimed at the device that is likely to produce the maximum emission at the frequency of measurement.
Only one test shall be carried out on the same passenger car or truck.
The towing vehicle shall be tested under static and low speed driving conditions. During the static test, the auxiliary converter shall be operated (the maximum emission level may not be generated under the maximum load condition), and the traction converter shall be powered but not operated. The antenna should be aligned with the centerline of the vehicle, otherwise select a location that is expected to produce a greater emission level.
During the slow running test, the speed should be appropriate, not only to avoid contact arcing or jumping, but also suitable for electric braking. The urban vehicle speed should be (20±5)km/h. The speed of trunk line vehicles should be (50±10)km/h. When passing through the antenna, the rolling stock should accelerate or decelerate within a given speed range with about 1/3 of its maximum traction force
If the following conditions are met, the static test of mechanical braking can be used instead of the slow running test for the rolling stock working under 1/3 of its maximum traction force:
-The towing equipment can work at rest;
-If a different circuit is not used in the brake, the electric brake is not tested.
If the static test with traction force replaces the slow running test, the limit requirements of the slow running test shall be adopted, and the reasons for the substitution shall be stated in the test report.
For vehicles powered by on-board energy storage equipment for traction, slow running test and limit requirements shall be adopted for the charging process.
2, train and vehicle radio frequency electromagnetic disturbance emission limits
The emission limit is given in two modes: static test and slow running test. The emission limit of static test is shown in Figure 11. The emission limit of slow running test is shown in Figure 12.
Fig. 11 Static Test Limits from 150 kHz to 1GHz (Quasi-Peak, 10 m Method)
Description:
A limit curve-applicable to other rail vehicles;
B Limit curve-applicable to trams/trolleybuses in urban streets.
Since there are no significant sources of interference at frequencies above 1 GHz, the emission limit is only specified to 1 GHz. Microprocessor equipment may generate emissions greater than 1GHz. The requirements of GB/T 243384 shall be met.
Fig. 12 Limits of 150 kHz ~ 1GH Slow Running Test (Peak 10m Method)
Description:
A limit curve-applicable to AC 25 kV powered vehicles;
B Limit curve-applicable to AC 15 kV DC 3 kV and 1500 powered vehicles;
C limit curve-applicable to DC 750 V or 600 V powered vehicles and trams/trolleybuses.
All values are peak values measured by the 10 m method.
Unless otherwise specified (such as the application of low-voltage electrified lines), diesel locomotives and diesel EMUs shall meet the requirements of limit curve A in Figure 1 and limit curve B in Figure 2.
The applicable frequency range of the emission limit is not more than 1GHz, and the emission above 1GHz caused by the microprocessor controller shall meet the requirements of GB/T 24338.4.
3. Experimental conditions for electromagnetic compatibility of electrical and electronic equipment for rail rolling stock
It is usually not possible to perform electromagnetic compatibility tests for each function of the equipment, and the tests should be carried out under typical working conditions approved by the manufacturer (simulating the field working conditions when the equipment produces the maximum emission or has the maximum sensitivity to noise). The manufacturer shall specify the test conditions in the test program.
The test shall specify the system configuration and operation mode of the test, and the test report shall record the actual test conditions and meet the relevant requirements of GB/T 17626.2 ~ GB/T17626.6.
If the equipment is part of the system or can be connected to auxiliary equipment, the equipment should be in accordance with the minimum system configuration.
GB/T 9254 Test.
If the device has a large number of ports with similar electrical characteristics or connects similar ports, a sufficient number of ports should be selected (for example, select
4 ports or 20% of the total) Simulate field conditions to ensure that all different types of ports are covered.
4. Launch requirements for electromagnetic compatibility of electrical and electronic equipment for rail rolling stock
The emission test and limits are specified according to the port type, as shown in Table 1 ~ Table 3.
Each type of interference shall be measured under defined and repeatable conditions. Table 1 ~ Table 3 gives the specific requirements of the test, and the basic standards given in Table 1 ~ Table 3 are limited to the test method and test configuration using these standards.
Table 1
Table 2
Table 3
5. Immunity requirements for electromagnetic compatibility of electrical and electronic equipment of rail rolling stock
Table 4 ~ Table 6 gives the specific requirements of the test, and the basic standards given in Table 4 ~ Table 6 are limited to the test instructions, test methods and test settings using these standards.
The test method shall be clear and the test results shall be reproducible. The test shall be carried out item by item, and the test sequence can be selected.
In order to ensure the immunity level of the entire rolling stock, the limits apply to all rolling stock equipment.
An electromagnetic compatibility management plan should be developed to ensure that the installation or replacement of new equipment on existing rolling stock will not degrade EMC performance.
Table 4
Table 5
Table 6
Emission and immunity of 4. signals and communication equipment
The emission and immunity of GB/T 24338.5 signal and communication equipment is applicable to the equipment installed in the rail transit environment and working normally included in GB/T 24338.4, as well as the communication signal data line and power line connected to the equipment under test.
The emission and immunity requirements of on-board signal and communication equipment are specified by GB/T 24338.4, and the emission and immunity requirements of signal and communication equipment installed in and connected to the substation are specified by GB/T 24338.6. The electromagnetic compatibility requirements for equipment within the scope of GB 17625.1 or GB/T 17625.2 are specified by GB 17625.1 or GB/T 17625.2.
If the emission of the equipment meets the emission limit specified in GB/T 17799.4, as long as the emission of any DC power port is less than the specified emission limit of the AC power port, it will also meet the provisions of this part.
The immunity requirements specified in this part apply:
-Key equipment, such as interlocking system and signal control system;
-Equipment within 3m area;
-Equipment within 10m area and has connection port with equipment within 3m area;
-Equipment within 10m area with cable more than 30m connected
Note: 3m area: the area along the line on both sides of the track and not more than 3m from the center line of the nearest rail
10m area: the line area on both sides of the track and more than 3m but not more than 10m from the nearest rail center line
1, emission limit requirements
The maximum emission of signal and communication equipment shall meet GB 17799.4/EN61000-6-4, and the conducted emission limit shall be applicable to both AC power port and DC power port. For specific limit requirements, please refer to Table 3 ~ Table 5 of GB 17799.4.
Figure 13th Century Huize Laboratory Test Layout
2, immunity test
The immunity of signal and communication equipment shall be tested item by item under clear and repeatable test conditions, and the test sequence can be selected. The test conditions, environmental disturbances, test methods and test configurations specified in the basic standards are shown in Table 7 ~ Table 11. If the equipment has a large number of ports with similar electrical characteristics or similar ports, select a sufficient number of ports (for example, 20% of the total number of ports or at least 4 ports) to simulate field conditions to ensure that all different types of ports are covered.
1) Electrostatic discharge test
Electrostatic discharge test shall be carried out according to GB/T 17626.2. Contact discharge shall be ± 6KV and air discharge shall be ± 8KV. See Table 7 for detailed requirements.
Figure 14 Century Huize Laboratory Test Layout
2) RF electromagnetic field (AM AM) test
For the RF electromagnetic field test, the frequency range is 80MHz ~ 6000MHz, and 80% AM and 1kHz modulation are adopted. See Table 7 for detailed requirements.
Fig. 15th Century Huize Laboratory Test Layout
3) Power frequency magnetic field test
For AC traction system, the interference of 100A/m,50Hz and test time ≥ 10s shall be applied; for DC traction system, the interference of 300A/m shall be applied; and the performance criterion is A, see Table 7 for detailed requirements.
Figure 16th Century Huize Laboratory Test Layout
4) Electric fast pulse group
The electrical fast pulse group needs to be applied to the I/O port, DC power port, AC power port and grounding port. The test basis is GB/T17626.4, and the performance criterion is A. See Table 8 ~ Table 11 for detailed requirements.
Figure 17 Century Huize Laboratory Test Layout
Table 7
5) Surge
According to GB/T17626.5, the surge shall be applied to the I/O port, DC power port and AC power port. The test performance criterion is B. See Table 8 ~ Table 10 for detailed requirements.
Figure 18th Century Huize Laboratory Test Layout
6) Conducted disturbance induced by RF field
According to GB/T17626.6, the conducted disturbance induced by radio frequency field shall be applied to I/O port, DC power port, AC power port and grounding port. The test performance criterion is A. See Table 8 ~ Table 11 for detailed requirements.
Figure 19th Century Huize Laboratory Test Layout
Table 8
Table 9
Table 10
Table 11
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