Interpretation of EN 50155: 2017 standard for power supply requirements and safety & EMC part of rail transit on-board equipment_Century Wisdom (Suzhou) Testing Technology Co., Ltd

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Interpretation of EN 50155: 2017 standard for power supply requirements and safety & EMC part of rail transit on-board equipment

Release time:

2022-09-22 00:00

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　　Key words: rail transit; on-board equipment; DC/DC power module selection; type test; test level judgment

　　0 Preface

　　EN 501 55 is a common certification standard for rail products. Its 2007 version has been used in the industry for many years. The latest version is the 2017 version, which was officially promulgated on April 13, 2018. This standard provides guidance on design, manufacturing and documentation requirements for equipment installed on rolling stock, and specifies test and evaluation methods. This standard test chapter covers the test requirements of electrical safety, electromagnetic compatibility and environment, etc. This article provides a detailed interpretation for the purpose of providing certain references for relevant personnel.

　　1 Performance Judgment Criteria

　　A default set of performance requirements is specified in the EN 50155:2017 standard, and different performance levels may be requested during the bidding phase. The minimum performance criteria shall be determined through consultation between the manufacturer and the user. The minimum performance level or allowable performance reduction shall be described in the test program provided by the entrusting party. The performance criteria criteria are defined as follows.

　　A) Performance criterion A

　　The equipment can continue to work as expected during and after the test. No performance degradation or loss of functionality is permitted, nor are changes to actual operating state or stored data permitted. The minimum performance level may be substituted for the normal performance level (all functions work as specified) if agreed between interested parties.

　　B) Performance criterion B

　　After the test, the equipment shall continue to operate as intended. During the experiment, performance degradation was allowed but no changes to the actual operating state or stored data were allowed.

　　C) Performance Criterion C

　　Temporary loss of function is allowed during the test, but the equipment should meet one of the following two conditions.

　　1) The automatic restart should achieve normal performance within the maximum specified time, after which, the device should maintain the previous operating state and work as expected, and no loss of important data is allowed;

　　2) Manual restart or restart by operator control: In this case, it should be negotiated between user and supplier or clearly defined in the user manual, which should be available to the user during the bidding stage.

　　2 List of test items

　　The type test items of electrical and electronic equipment installed on rolling stock are shown in Table 1, and the test sequence is not mandatory. The test plan should indicate the tests to be performed and the sequence of tests to be followed. Type tests shall be carried out in accordance with the test specifications and test procedures written by the supplier.

　　Table 1 List of test items

serial number	Pilot projects	type test
1	Visual inspection	M
2	performance test	M
3	power supply test	M
4	insulation test	M
5	Low temperature storage test	O
6	Low temperature start test	M
7	Dry heat test	M
8	Alternating Damp Heat Test	M
9	Salt spray test	O
10	Enclosure protection test ( IP rating )	O
11	Electromagnetic Compatibility Test	M
12	Vibration and Shock Test	M
13	stress screening test	O
14	Rapid Temperature Shock Test	O

　　M in the test requirements in the above table stands for mandatory test; O stands for agreement test between the supplier and the user.

　　3 Power supply selection of vehicle electronic equipment

　　As one of the methods to prevent the spread of faults, isolated power supply plays an important role in vehicle electronic equipment; however, during the operation of the vehicle, there are various states, such as severe vibration state; severe external environment temperature change rate, etc. It is difficult for ordinary conventional industrial-grade power supplies to meet their use requirements; so what requirements do vehicle power supplies need to meet?

　　3.1 Shock and vibration

　　Due to the nature of the environment in which railways operate, rolling stock is subject to shock and vibration. Random vibration and shock test requirements must be carried out for electronic equipment installed on railway vehicles. For the power module, using glue to fix the onboard components can effectively enhance its ability to resist vibration and shock.

　　The rated power supply voltage of the on-board battery mainly has the following types: 24V, 48V, 72V, 96V, 110V and other 5 specifications; due to the start-up of auxiliary equipment or the switching of inductive loads, surge voltage or low voltage will occur; the input of power supply design The voltage parameters can work normally within the voltage range of 0.6VN and 1.4VN; and the power supply manufacturers are compatible with multiple vehicle battery voltage levels.

　　3.2 Isolation Electrical Requirements

　　The test voltage of the dielectric test (withstanding voltage test) of vehicle-mounted electronic equipment is related to the power supply voltage of the vehicle-mounted battery, and the relevant requirements are as follows:

　　Table 2 Relationship between isolation withstand voltage and battery voltage

Vehicle battery	Isolation withstand voltage requirements
24V	500VAC/50Hz/1min
48V	500VAC/50Hz/1min
72~125V	1000VAC/50Hz/1min

　　If the power supply type of the on-board electronic equipment is uncertain, for example, the 110V battery may float to above 125V or the low voltage may generate a voltage greater than 125V; it is recommended to use 1500VAC isolation requirements, which can meet the electrical isolation requirements during instantaneous overvoltage.

　　3.3 Temperature and Humidity Requirements

　　In order to meet the temperature range and humidity range requirements of long-distance railway locomotives, the on-board power supply is required to meet the operating requirements of the ambient temperature -40°C~85°C, and it needs to be verified by reliability type tests such as high and low temperature cycles and humidity and heat alternation. Jinshengyang railway power supply products are designed and produced in accordance with strict quality control system, and can pass the type reliability test required by railways.

　　3.4 Special surge requirements

　　Each country has inconsistent requirements for special surges, for example: British Railway Standard RIA12 "General Specifications for Transient Surge Protection in DC Control Systems for Dragging and Carrying Equipment" (overseas, this sentence can be deleted; or FAE provides Standard English version name), it is required that the electronic equipment connected to the battery of the power supply must be able to withstand two waveforms: one is 1S 1.5 times the input voltage waveform, the other is 3.5 times the input voltage, and the surge voltage lasts 20mS. The source impedance of the surge pulse voltage is 0.2Ω. If the rated voltage of the power supply battery is considered to be 110VDC, it is difficult to absorb (assuming the clamping voltage VC is 160VDC) up to = 2475J of energy if only a single clamping device is used for protection. , it is difficult for general transient clamp suppression devices to meet the requirements, and special circuits or modules are required to meet the standard requirements.

　　3.5 Other requirements

　　For power supply interruption, drop and other requirements, the general module power supply design is difficult to meet the 10mS interruption requirement, and it is necessary to increase the peripheral input and output capacitors to meet customer needs.

　　4 Test methods and requirements for safety and EMC

　　4.1 Insulation test

　　4.1.1 Insulation resistance test

　　The insulation resistance measurement test should be carried out at 500 VDC, and the insulation resistance measurement should be carried out before the withstand voltage test and the insulation resistance value should be recorded. After the withstand voltage test, measure the insulation resistance, and the result should be greater than 20 MΩ. After the insulation test, the equipment should work as intended and within the specified limits. During the test, the device should not be powered.

　　4.1.2 Voltage withstand test

　　The withstand voltage test shall be performed with AC (50 Hz or 60 Hz) or DC test voltage. Apply the test voltage by gradually increasing the voltage amplitude to the test voltage, and the test time is 1 min. During the test, the device should not be powered. For voltage supply equipment not covered by the EN 50155:2017 standard, the value of the test voltage shall comply with the provisions in Table 3. There should be no breakdown or flashover during the withstand voltage test. After the test, the equipment should work as expected and within the specified range.

　　Table 3 Test voltage for withstand voltage test

Nominal battery voltage or I/O port voltage	Test voltage
< 72 VDC or 50 VAC rms	500 VAC or 750 VDC
72 VDC ≤ VDC < 125 VDC or 50~90 VAC rms	1 000 VAC or 1 500 VDC
125 VDC ≤VDC < 315 VDC 或90 ~ 225 VAC rms	1 500 VAC or 2 200 VDC

　　4.2 Power supply test

　　A) Power supply range test

　　The power supply terminals of electronic equipment should be able to work normally under the voltage values shown in Table 4. A device will neither fail nor cause other devices to fail at supply voltages from zero to maximum. When the supply voltage is within the continuous voltage range, the device shall restart in normal operating mode.

　　Table 4 Continuous voltage range

Nominal voltage U n	limit value
Minimum continuous voltage	0.7U no
Maximum continuous voltage	1.25U n

　　B) Power supply temporary overvoltage test

　　When the duration of the voltage of 1.4U n does not exceed 0.1 s, it should not lead to functional deviation, and the equipment should meet performance criterion A. The equipment shall meet performance criterion B when the duration of the electric value with a voltage value of 1.4U n does not exceed 1 s. The test should be repeated 10 times. The test waveform is shown in Figure 2-3.

　　Figure 2 Temporary overvoltage test waveform

　　Figure 3 Temporary overvoltage test waveform

　　C) Power supply voltage sag test

　　When the power supply voltage dips to 0.6U n, when the duration of this voltage does not exceed 0.1 s, it should not cause the function to be reduced, and the equipment should meet the performance criterion A. The test should be repeated 10 times. The test waveform is shown in Figure 4.

　　Figure 4 Voltage sag test waveform

　　D) Mains voltage interruption test

　　The test is divided into three grades: S1, S2 and S3, and the test requirements are shown in Table 5. The choice of test level shall be defined by the system integrator; unless otherwise specified, the requirements of category S2 apply. The power supply voltage interruption test waveform is shown in Figure 5.

　　Table 5 Power supply voltage interruption level

grade	Test requirements	interruption duration
S1	No performance judgment is made , but the equipment should continue to operate as specified after a voltage interruption	no request
S2	The equipment shall meet performance criterion A	10 ms
S3	The equipment shall meet performance criterion A	20 ms

　　Figure 5 Power supply voltage interruption test waveform

　　E) Power supply voltage change test

　　1) Level C1: The voltage is at 0.6U n (without interruption) for 100 ms, and the equipment should meet the performance criterion A. The power supply voltage change of level C1 is shown in Figure 6.

　　2) Class C2: The equipment shall meet performance criterion B during a 30 ms power interruption starting from U n. A power interruption is an open circuit rather than a short circuit "high impedance condition". Unless otherwise specified, category C1 requirements apply only to the power supply. The change of C2 grade power supply voltage is shown in Fig.7.

　　Figure 6 Power supply voltage change level C1

　　Figure 7 Power supply voltage change level C2

　　4.3 Electromagnetic compatibility test

　　All EMC tests shall be carried out in accordance with the EN 50121-3-2:2016 standard. Test items, test requirements and performance criteria are shown in Table 6. The definition of performance criterion A, performance criterion B and performance criterion C in the electromagnetic compatibility test is based on the requirements in the standard EN 50121-1.

　　Table 6 Electromagnetic Compatibility Test

Pilot projects	Test requirements	performance criterion
Conducted emission test	150 ~ 500 kHz , the peak limit is 99 dBuV ; 500 kHz to 30 MHz with a peak limit of 93 dBuV	/
30 MHz~1 GHz radiation disturbance test	30~230 MHz , quasi-peak limit is 50 dBuV/m ; 230 MHz~1 GHz , the quasi-peak limit is 57 dBuV/m	/
1~6 GHz radiation disturbance test	1~3 GHz , the peak limit is 76 dBuV/m ; the average limit is 56 dBu V /m ; 3~6 GHz , peak limit is 80 dBuV/m , average limit is 60 dBu V /m	/
Harmonic Distortion Test	Frequency : 50 Hz ~ 2 kHz , THD ＜8%	/
Electrostatic Discharge Immunity Test	Contact discharge ± 6 kV ; air discharge ± 8 kV	B
Surge ( shock ) immunity test	Waveform : 1.2/50 u s ; Line to ground : ± 2 kV , 42 Ω , 0.5 uF ; Line - to-line : ± 1 kV , 42 Ω , 0.5 uF	B
Electrical fast transient burst immunity test	Peak : ± 2 kV ( power and signal lines ); T r / T h test waveform : 5/50 ns ; Repetition rate : 5 kHz	A
Conducted Immunity Test	0.15~80 MHz； 10 V （rms）； 80%AM， 1 kHz	A
Radio Frequency Electromagnetic Field Radiation Immunity Test	80~800 MHz， 20 V/m， 80%AM， 1 kHz	A
( Digital Cordless Telephone ) Radio Frequency Electromagnetic Field Radiation Immunity Test	800~1000 MHz， 20 V/m， 80%AM， 1 kHz； 1400~2000 MHz， 10 V/m， 80%AM， 1 kHz； 2000~2700 MHz， 5 V/m， 80%AM， 1 kHz； 5100~6000 MHz， 3 V/m， 80%AM， 1 kHz；	A

　　5 Conclusion

　　This paper analyzes the requirements of on-board electronic equipment, and then provides guidance for the correct selection of DCDC isolated power supply modules for rail transit on-board electronic equipment, which is of great significance for the reliable use of railway module power supplies. At the same time, it interprets the type test items in the test chapter of the EN 50155: 2017 standard, namely the performance test, insulation test, electromagnetic compatibility test requirements and test method level judgment, and carries out relevant tests for electrical and electronic devices used on rolling stock Some references are provided.

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