electromagnetic susceptibility test procedure for the digital protecting ...
ELECTROMAGNETIC SUSCEPTIBILITY TEST PROCEDURE FOR THE DIGITAL PROTECTING RELAY Name(s): Jian-Long Kuo1, Tsung-Yu Wang2, Jiann-Der Lee2 Affiliation: Institute of Systems and Control Engineering, National Kaohsiung First University of Science and Technology, 2 Department of Electrical Engineering, Chang-Gung University Address: 1 ,2Nantze, Kaohsiung 811, 2Kwei-Shan, Tao-Yuan 333 Country: TAIWAN. 1
ABSTRACT-This paper will discuss the EMS (electromagnetic susceptibility) test procedure for the digital protecting relay. The tested EUTs for the EMS test comprise the microprocessor and the power supply of the digital protecting relay. In this paper, an EMS equipment will be employed to program several test waveforms based on the IEC power quality measurement standard such as IEC1000-4-11 for testing the EUTs, so that the digital protecting relay can meet the product gauge.
the testing of two different load sets. In table 1, the different load sets, the critical load set and the over critical load set, are illstrated respectively.
KEY WORDS-electromagnetic susceptibility, digital protecting relay, IEC standard, power quality.
Fig. 1. (a) the switching power supply and (b) its input/output configurations.
1. Introduction In 2004, our laboratory had cooperated with the NAN YA PLASTICS COPORATION, TAIWAN to develop a digital protecting relay. The digital protecting relay needs to be tested to meet the product gauge such as IEC standard [1,2]. Digital protecting relay having a microprocessor and a power supply is used to execute the over current protection of the power system. The power supply is designed to provide the power of the microprocessor. However, the operation of the power supply always affects the power quality of the power system because of its nonlinear properties. Therefore, the EMS test for the microprocessor and the power supply will be discussed based on respective measurement standard [3] in this paper. The power supply provides a stable DC output voltage, so as to supply at least one external load. However, when the load is over the rated of the power supply, The DC output voltage of the power supply will cause unstable voltage distortion. In this paper, the power supply provides four voltage levels to flexibly supply four different external loads. The switching power supply is shown in Fig. 1(a) and (b). The EMS test for the power supply will mainly focus on
Table 1. Load testing for each dc output voltage of the power supply. DC out voltage Testing for critical Testing for over (V) load (W) critical load test (W) +12V 2.11 (with 68 ohm) 4.36 (with 33 ohm) -12V 1.15 (with 125 ohm) 1.75 (with 82 ohm) +5V 0.5 (with 50 ohm) 1.14 (with 22 ohm) +24V 2.30 (with 250 ohm) 4.61 (with 125 ohm) Total load 6.07 11.86
Furthermore, in case of the lightning and the voltage variation [3], the power supply and the microprocessor needs to be normally operated to guarantee the reliability of the digital protecting relay. In this paper, the testing of the power supply and the microprocessor is full compliance with the IEC test standard [4-6], such that the digital protecting relay can safely operate.
2. EMS Test This paper emphasizes the EMS testing of the power supply and the microprocessor of the digital protecting relay in accordance with the IEC1000-4-11 standard. For the rigorous product gauge, the EMI will also be considered in this test, especially for the test of the microprocessor. Fig. 2 shows the flow chart of the EMS testing, the test waveforms based on the IEC1000-4-11 standard can be programmed by using the EMS instrument
(SWITCHING AMPLIFIER, SW5250A). In Fig. 2, the EMS instrument is further connected to an EMI instrument. The test waveforms programmed by the EMS instrument will pass through the EMI instrument to the EUTs for testing. Accordingly, the flow chart includes not only the EMS test but also the EMI test. According to the IEC standard, it gauges several test standard including voltage spike, voltage dropout, inrush current, variations, and interruptions. However, the power system always unexpectedly occurs the above problems. To improve the power quality and the control stability of the power system, the digital protecting relay has to strictly execute the above test. The test steps and its results are detailed discussed in the following sections.
3. EMS Test for the Microprocessor The microprocessor is a kernel of the digital protecting relay. It is used to rapidly shut the power system when the power system occurs the over current. However, if the microprocessor is a sensitive component, the maloperation may be occurred. Therefore, the microprocessor needs to be tested under the IEC standard. The detailed EMS test including the EUTs with/without the EMI filter will be discussed below. 3.1. Voltage Dropout Test In the field of power system, the voltage dropout is one of the common problems of the power quality. In Fig. 4(a), it can be clearly observed that a voltage is rapidly dropped within one period. The voltage dropout can instantaneously break the inductive load and produce the mal-operation for the capacitive load. Therefore, the microprocessor has to be measured to meet the voltage dropout test. The parameter about the voltage dropout test is shown in table 2. Table 2 parameters setting for voltage dropout test Frequency Amplitude Dropout Phase Sustained period 60Hz 150V 45deg. 1ms
Fig. 2. the flow chart of the EMS testing.
For the test flow chart, the EMI instrument needs to be provided a power about 300V. Therefore, in Fig. 2, a transformer having the turn ratio n=2 is connected between the EMS and EMI instrument. In other word, the lower power about 150V is just needed to be supplied, so as to protect the EMS instrument. The test configuration and experimental set up are shown in Fig. 3.
3.2. Inrush Current Test As shown in Fig. 4(b), the inrush current is programmed to test the microprocessor. The parameter about the inrush current test is shown in table 3. Table 3 parameters setting for inrush current test Frequency Amplitude Inrush phase Inrush time 60Hz 150V 90deg. 4.17ms
3.3. Voltage Spike Test Voltage spike is caused by the inductive or capacitive load. In Fig. 4(c), The voltage spike is instantaneously interrupted within one period. The voltage spike is always formed a impulse to strike the digital component, especially the microprocessor, such that the microprocessor hence produces the mal-operation because of its sensitive property. To increase the reliability of the digital protecting relay, it also needs to be tested for EMS testing. The parameter about the voltage spike test is shown in table 3. Table 4 parameters setting for voltage spike test Frequency Amplitude Spike Phase Sustained period 60Hz 150V 32deg 0.09ms
Fig. 3. EMS equipment.
Table 5 test results for the microprocessor under the voltage dropout, inrush current, and voltage spike test. With EMI filter Without EMI filter result DC output result DC output voltage voltage Voltage dropout normal 4.86 V normal 4.85 V Inrush Current normal 4.76 V normal 4.81 V Voltage Spike normal 4.91 V normal 4.83 V
4. EMS Test for the Power Supply
(a) Voltage Dropout test
(b) Inrush Current test
When the lightning or the switching transient occurs in the power system, the power supply of digital protecting relay will be severely affected. The power supply is a cascade configuration, and it provides a plurality of outputs including +12V, -12V, +5V, and +24V to supply a plurality of the external loads. However, when the power supply is affected by the lightning or the switching transient, all the external loads connected to the power supply will also be affected and therefore the unexpected mal-operation occurs. Accordingly, the EMS test for the IEC standard is very important for the power supply. In this paper, the power supply with the two different external load sets shown in table 1 will be tested in accordance with the IEC1000-4-11. The IEC1000-4-11 standard was published in 1994. It is a test standard for the electric and electronic products having the current rated under 16A. Furthermore, the IEC1000-4-11 standard is corresponding with the B class, EN61000 european standard. Accordingly, the paper in accordance with the IEC1000-4-11 standard will explicitly gauge the power supply about the variations and interruptions test. 4.1. Variations In Fig. 5 and table 6, the voltage variations are imposed on the power supply for testing. More specified, the test voltage range from 60V to 260V is segmented as six levels. Each level is increased by 40V for testing the reliabilities of the DC outputs. In table 6, it shows that the power supply operated at the voltage range from 100V to 240V is reliable. However, the outputs of the power supply operated at the 60V will be caused severe distortion.
(c) Voltage Spike test Fig. 4. Test waveforms programmed by the EMS equipment.
For the microprocessor, the test results for the above three IEC standard are shown in table 5. The results show that the microprocessor still can normally work to supervise the over current of the power system. It will not be affected by the above three abnormal waveforms. In other words, the reliability of the protection strategy can be guaranteed because the microprocessor can meet the above three IEC standard test.
Fig. 5. Variations programming.
Table 6 test results for the power supply under the variations test. Test voltages (dV=40V) 60V -12V +12V +5V +24V
-6.6V 5.68V 2.93V 10.3 V
100V
140 V
180 V
220 V
260 V
-12.04V -12.04V -12.04V -12.04V -12.14V 11.96V 11.96V 11.96V 11.96V 11.96V 4.92V 4.92V 4.92V 4.91V 4.91V 24.1 V 24.1 V 24.1 V 24.1 V 24.1 V
(c)
(g) DC output voltage +5V (X200)
4.2. Interruptions The interruption waveforms are illustrated in Fig. 6(a), 7(a), and 8(a). The voltage is dropped to an predetermined voltage magnitude to simulate the interruption. Furthermore, the predetermined voltage magnitude is kept several cycles. The voltage interruption can be programmed by the EMS instrument. It will be applied to the power supply for testing the reliabilities of the DC outputs. The DC outputs of the power supply are further connected to the respective loads. In this paper, the two different load sets are selected from table 1. One is the critical load condition; the other is the over critical load condition. The test results in Fig. 6(b) to (e), Fig. 7(b) to (e), and Fig. 8(b) to (e) show that the DC outputs of the power supply are acceptable when the DC outputs connect to the critical load condition. However, in Fig. 6(f) to (i), Fig. 7(f) to (i), and Fig. 8(f) to (i), all the DC outputs of the power supply distort when the over critical load is connected.
(d)
(h) DC output voltage +12V (X200)
(e)
(i) DC output voltage -12V (X200)
Fig. 6. Interruptions programming and the measurements of the DC output voltage.
(a) interruptions programming (voltage interruption from 80V to 40V and keeping 12 cycles or 200ms ) (a) interruptions programming (voltage interruption from 80V to 0V and keeping 2 cycles or 30ms )
(b)
(f) DC output voltage +24V (X200) (b)
(f) DC output voltage +24V (X200)
(c)
(g) DC output voltage +5V (X200)
(d)
(g) DC output voltage +5V (X200)
(h) DC output voltage +12V (X200)
(e)
(c)
(d)
(h) DC output voltage +12V (X200)
(i) DC output voltage -12V (X200)
(e)
(i) DC output voltage -12V (X200)
Fig. 7. Interruptions programming and the measurements of the DC output voltage.
Fig. 8. Interruptions programming and the measurements of the DC output voltage.
5. Conclusion The digital protecting relay has been completely tested in accordance with the IEC test standard, especially for testing the sensitive components such as microprocessor and power supply. For the power supply, the two comparable external load sets are further tested respectively such that the power supply is capable of meeting the IEC1000-4-11 standard to obtain the reliable DC outputs of the power supply.
Acknowledgements (a) interruptions programming (voltage interruption from 256V to 0V and keeping 10 cycles or 160ms )
Thanks the NAN YA COPORATION, TAIWAN for providing the test equipment and the financial support. Also thanks to Tseng Tzeng for typing the article kindly.
References
(b)
(f) DC output voltage +24V (X200)
[1] Limits and methods of measurement of immunity characteristics of information technology equipment (Standard ECMA-237, June 1996). [2] Catalyst 2950 Switch hardware installation guide (Technical Specifications, Appendix A). [3] D.R. Coulson, EMC techniques for microprocessor software, IEE Colloquium on EMC for the Small Business, 1998, 5/1-5/6. [4] Weihua Chen, Handbook of EMC (China Engineering Industry Press, 1998, 301-307).
[5] Zhiyong Yu, Guangbin Liu, & Hong Wu, EMC techniques for microprocessor software, International Symposium on Electromagnetic Compatibility, 2002, 67-70. [6] M. H. J. Bollen & I. Y. H. Gu, Characterization of voltage variations in the very-short time-scale, IEEE Trans. Power Delivery, 18(2), 2005, 1198-1199.
ABSTRACT-This paper will discuss the EMS (electromagnetic susceptibility) test procedure for the digital protecting relay. The tested EUTs for the EMS test comprise the microprocessor and the power supply of the digital protecting relay. In this paper, an EMS equipment will be employed to program several test waveforms based on the IEC power quality measurement standard such as IEC1000-4-11 for testing the EUTs, so that the digital protecting relay can meet the product gauge.
the testing of two different load sets. In table 1, the different load sets, the critical load set and the over critical load set, are illstrated respectively.
KEY WORDS-electromagnetic susceptibility, digital protecting relay, IEC standard, power quality.
Fig. 1. (a) the switching power supply and (b) its input/output configurations.
1. Introduction In 2004, our laboratory had cooperated with the NAN YA PLASTICS COPORATION, TAIWAN to develop a digital protecting relay. The digital protecting relay needs to be tested to meet the product gauge such as IEC standard [1,2]. Digital protecting relay having a microprocessor and a power supply is used to execute the over current protection of the power system. The power supply is designed to provide the power of the microprocessor. However, the operation of the power supply always affects the power quality of the power system because of its nonlinear properties. Therefore, the EMS test for the microprocessor and the power supply will be discussed based on respective measurement standard [3] in this paper. The power supply provides a stable DC output voltage, so as to supply at least one external load. However, when the load is over the rated of the power supply, The DC output voltage of the power supply will cause unstable voltage distortion. In this paper, the power supply provides four voltage levels to flexibly supply four different external loads. The switching power supply is shown in Fig. 1(a) and (b). The EMS test for the power supply will mainly focus on
Table 1. Load testing for each dc output voltage of the power supply. DC out voltage Testing for critical Testing for over (V) load (W) critical load test (W) +12V 2.11 (with 68 ohm) 4.36 (with 33 ohm) -12V 1.15 (with 125 ohm) 1.75 (with 82 ohm) +5V 0.5 (with 50 ohm) 1.14 (with 22 ohm) +24V 2.30 (with 250 ohm) 4.61 (with 125 ohm) Total load 6.07 11.86
Furthermore, in case of the lightning and the voltage variation [3], the power supply and the microprocessor needs to be normally operated to guarantee the reliability of the digital protecting relay. In this paper, the testing of the power supply and the microprocessor is full compliance with the IEC test standard [4-6], such that the digital protecting relay can safely operate.
2. EMS Test This paper emphasizes the EMS testing of the power supply and the microprocessor of the digital protecting relay in accordance with the IEC1000-4-11 standard. For the rigorous product gauge, the EMI will also be considered in this test, especially for the test of the microprocessor. Fig. 2 shows the flow chart of the EMS testing, the test waveforms based on the IEC1000-4-11 standard can be programmed by using the EMS instrument
(SWITCHING AMPLIFIER, SW5250A). In Fig. 2, the EMS instrument is further connected to an EMI instrument. The test waveforms programmed by the EMS instrument will pass through the EMI instrument to the EUTs for testing. Accordingly, the flow chart includes not only the EMS test but also the EMI test. According to the IEC standard, it gauges several test standard including voltage spike, voltage dropout, inrush current, variations, and interruptions. However, the power system always unexpectedly occurs the above problems. To improve the power quality and the control stability of the power system, the digital protecting relay has to strictly execute the above test. The test steps and its results are detailed discussed in the following sections.
3. EMS Test for the Microprocessor The microprocessor is a kernel of the digital protecting relay. It is used to rapidly shut the power system when the power system occurs the over current. However, if the microprocessor is a sensitive component, the maloperation may be occurred. Therefore, the microprocessor needs to be tested under the IEC standard. The detailed EMS test including the EUTs with/without the EMI filter will be discussed below. 3.1. Voltage Dropout Test In the field of power system, the voltage dropout is one of the common problems of the power quality. In Fig. 4(a), it can be clearly observed that a voltage is rapidly dropped within one period. The voltage dropout can instantaneously break the inductive load and produce the mal-operation for the capacitive load. Therefore, the microprocessor has to be measured to meet the voltage dropout test. The parameter about the voltage dropout test is shown in table 2. Table 2 parameters setting for voltage dropout test Frequency Amplitude Dropout Phase Sustained period 60Hz 150V 45deg. 1ms
Fig. 2. the flow chart of the EMS testing.
For the test flow chart, the EMI instrument needs to be provided a power about 300V. Therefore, in Fig. 2, a transformer having the turn ratio n=2 is connected between the EMS and EMI instrument. In other word, the lower power about 150V is just needed to be supplied, so as to protect the EMS instrument. The test configuration and experimental set up are shown in Fig. 3.
3.2. Inrush Current Test As shown in Fig. 4(b), the inrush current is programmed to test the microprocessor. The parameter about the inrush current test is shown in table 3. Table 3 parameters setting for inrush current test Frequency Amplitude Inrush phase Inrush time 60Hz 150V 90deg. 4.17ms
3.3. Voltage Spike Test Voltage spike is caused by the inductive or capacitive load. In Fig. 4(c), The voltage spike is instantaneously interrupted within one period. The voltage spike is always formed a impulse to strike the digital component, especially the microprocessor, such that the microprocessor hence produces the mal-operation because of its sensitive property. To increase the reliability of the digital protecting relay, it also needs to be tested for EMS testing. The parameter about the voltage spike test is shown in table 3. Table 4 parameters setting for voltage spike test Frequency Amplitude Spike Phase Sustained period 60Hz 150V 32deg 0.09ms
Fig. 3. EMS equipment.
Table 5 test results for the microprocessor under the voltage dropout, inrush current, and voltage spike test. With EMI filter Without EMI filter result DC output result DC output voltage voltage Voltage dropout normal 4.86 V normal 4.85 V Inrush Current normal 4.76 V normal 4.81 V Voltage Spike normal 4.91 V normal 4.83 V
4. EMS Test for the Power Supply
(a) Voltage Dropout test
(b) Inrush Current test
When the lightning or the switching transient occurs in the power system, the power supply of digital protecting relay will be severely affected. The power supply is a cascade configuration, and it provides a plurality of outputs including +12V, -12V, +5V, and +24V to supply a plurality of the external loads. However, when the power supply is affected by the lightning or the switching transient, all the external loads connected to the power supply will also be affected and therefore the unexpected mal-operation occurs. Accordingly, the EMS test for the IEC standard is very important for the power supply. In this paper, the power supply with the two different external load sets shown in table 1 will be tested in accordance with the IEC1000-4-11. The IEC1000-4-11 standard was published in 1994. It is a test standard for the electric and electronic products having the current rated under 16A. Furthermore, the IEC1000-4-11 standard is corresponding with the B class, EN61000 european standard. Accordingly, the paper in accordance with the IEC1000-4-11 standard will explicitly gauge the power supply about the variations and interruptions test. 4.1. Variations In Fig. 5 and table 6, the voltage variations are imposed on the power supply for testing. More specified, the test voltage range from 60V to 260V is segmented as six levels. Each level is increased by 40V for testing the reliabilities of the DC outputs. In table 6, it shows that the power supply operated at the voltage range from 100V to 240V is reliable. However, the outputs of the power supply operated at the 60V will be caused severe distortion.
(c) Voltage Spike test Fig. 4. Test waveforms programmed by the EMS equipment.
For the microprocessor, the test results for the above three IEC standard are shown in table 5. The results show that the microprocessor still can normally work to supervise the over current of the power system. It will not be affected by the above three abnormal waveforms. In other words, the reliability of the protection strategy can be guaranteed because the microprocessor can meet the above three IEC standard test.
Fig. 5. Variations programming.
Table 6 test results for the power supply under the variations test. Test voltages (dV=40V) 60V -12V +12V +5V +24V
-6.6V 5.68V 2.93V 10.3 V
100V
140 V
180 V
220 V
260 V
-12.04V -12.04V -12.04V -12.04V -12.14V 11.96V 11.96V 11.96V 11.96V 11.96V 4.92V 4.92V 4.92V 4.91V 4.91V 24.1 V 24.1 V 24.1 V 24.1 V 24.1 V
(c)
(g) DC output voltage +5V (X200)
4.2. Interruptions The interruption waveforms are illustrated in Fig. 6(a), 7(a), and 8(a). The voltage is dropped to an predetermined voltage magnitude to simulate the interruption. Furthermore, the predetermined voltage magnitude is kept several cycles. The voltage interruption can be programmed by the EMS instrument. It will be applied to the power supply for testing the reliabilities of the DC outputs. The DC outputs of the power supply are further connected to the respective loads. In this paper, the two different load sets are selected from table 1. One is the critical load condition; the other is the over critical load condition. The test results in Fig. 6(b) to (e), Fig. 7(b) to (e), and Fig. 8(b) to (e) show that the DC outputs of the power supply are acceptable when the DC outputs connect to the critical load condition. However, in Fig. 6(f) to (i), Fig. 7(f) to (i), and Fig. 8(f) to (i), all the DC outputs of the power supply distort when the over critical load is connected.
(d)
(h) DC output voltage +12V (X200)
(e)
(i) DC output voltage -12V (X200)
Fig. 6. Interruptions programming and the measurements of the DC output voltage.
(a) interruptions programming (voltage interruption from 80V to 40V and keeping 12 cycles or 200ms ) (a) interruptions programming (voltage interruption from 80V to 0V and keeping 2 cycles or 30ms )
(b)
(f) DC output voltage +24V (X200) (b)
(f) DC output voltage +24V (X200)
(c)
(g) DC output voltage +5V (X200)
(d)
(g) DC output voltage +5V (X200)
(h) DC output voltage +12V (X200)
(e)
(c)
(d)
(h) DC output voltage +12V (X200)
(i) DC output voltage -12V (X200)
(e)
(i) DC output voltage -12V (X200)
Fig. 7. Interruptions programming and the measurements of the DC output voltage.
Fig. 8. Interruptions programming and the measurements of the DC output voltage.
5. Conclusion The digital protecting relay has been completely tested in accordance with the IEC test standard, especially for testing the sensitive components such as microprocessor and power supply. For the power supply, the two comparable external load sets are further tested respectively such that the power supply is capable of meeting the IEC1000-4-11 standard to obtain the reliable DC outputs of the power supply.
Acknowledgements (a) interruptions programming (voltage interruption from 256V to 0V and keeping 10 cycles or 160ms )
Thanks the NAN YA COPORATION, TAIWAN for providing the test equipment and the financial support. Also thanks to Tseng Tzeng for typing the article kindly.
References
(b)
(f) DC output voltage +24V (X200)
[1] Limits and methods of measurement of immunity characteristics of information technology equipment (Standard ECMA-237, June 1996). [2] Catalyst 2950 Switch hardware installation guide (Technical Specifications, Appendix A). [3] D.R. Coulson, EMC techniques for microprocessor software, IEE Colloquium on EMC for the Small Business, 1998, 5/1-5/6. [4] Weihua Chen, Handbook of EMC (China Engineering Industry Press, 1998, 301-307).
[5] Zhiyong Yu, Guangbin Liu, & Hong Wu, EMC techniques for microprocessor software, International Symposium on Electromagnetic Compatibility, 2002, 67-70. [6] M. H. J. Bollen & I. Y. H. Gu, Characterization of voltage variations in the very-short time-scale, IEEE Trans. Power Delivery, 18(2), 2005, 1198-1199.
