Practical Papers, Articles and Application Notes Kye Yak See, Technical Editor
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rcing faults, if not detected early, can lead to electrical fires. An Arc Fault Detection Device (AFDD) aims to detect arcing faults that cannot be detected by circuit breakers or residual current devices. AFDD is an active electronic device that measures low and high frequency characteristics of the current passing through it. AFDD can be a potential source and victim of EMI, especially in a military electromagnetic environment, where low emission levels and high immunity levels are necessary. Janne P. Pulkkinen from Finnish Defence Forces, Finland, discusses the EMC requirements of AFDD in the first paper, “Commercial Arc Fault Detection Devices in Military Electromagnetic Environment”.
paper allow the readers to understand the antenna characteristics over perfect ground without complicated calculations.
The second paper, “Antenna Characteristics over Perfect Ground”, is contributed by Valentino Trainotti from the University of Buenos Aires, Argentina. He goes through a very detailed verification of a Friis equation between a transmitting antenna and a receiving antenna over a perfect ground that fulfils the natural energy conservation law. The radio link examples given in the
This will be the last issue of the EMC Magazine in 2018. It has been a wonderful year with a number of new authors contributing excellent practical EMC papers. If you have good EMC design case studies and practices to share with our readers, feel free to reach me at
[email protected]. Let me take this opportunity to wish you and your family a Happy New Year.
David Weston from EMC Consulting Inc., Ontario, authored the third and last paper “Analysis of Lightning Strike to an Imbedded Electronic Enclosure based on a Scale Model Test Setup”. He shows that even with the lack of a large lightning test facility, one can still use a scale model test setup to investigate the effects of lightning to electronic equipment imbedded into the fuselage of a plane. The results of the analysis provide insight of potential weakness of the electronics equipment so that the necessary protection circuits can be designed and installed.
Commercial Arc Fault Detection Devices in Military Electromagnetic Environment Janne P. Pulkkinen Finnish Defence Forces, Joint Systems Centre Abstract—Arc fault detection device (AFDD) is the latest protection device for low voltage circuits. It is used to detect arcing faults that cannot be detected by circuit breakers or residual current devices. Arcing faults are one of the main causes for electrical fires. Arc fault detection device is an active electronic device which operation is typically based on measurement of low and high frequency characteristics of the current passing through. Based on measured current characteristics and the knowledge of the arcing unique deviations in current, arc fault detection device detects possible arcing and disconnects the protected circuit. Arc fault detection device as an active electronic device is a potential source and victim of electromagnetic interference. Electromagnetic compatibility requirements are especially very demanding in military applications where low emission levels and high immunity levels are required. This article presents test results from electromagnetic compatibility testing of five different commercial arc fault detection devices against military standard requirements and analyses the suitability of the arc fault detection devices in military electromagnetic environment. Index Terms—Arc-fault circuit interrupter (AFCI), Arc fault detection device (AFDD), Electromagnetic compatibility (EMC), Electromagnetic interference (EMI)
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I. Introduction Arc fault detection device (AFDD) is a device that is used in 230 V 50 Hz single phase circuits. Requirements for AFDDs are defined in IEC 62606 standard [1]. The corresponding protection device for 120 V 60 Hz single phase circuits is the arc-fault circuit interrupter (AFCI) which has longer history in the U.S. and it is based on requirements of UL 1699 standard [2]. Typically AFDD is a combination of one module width arc fault detection unit and circuit breaker or residual current device. In some products all of these three protection devices are combined as one device to give protection against different parallel and serial faults. The operation of AFDD is based on measurement of AC current characteristics and in some applications voltage characteristics. As the arcing causes unique and detectable deviations to AC current and voltage, it is possible to protect circuits against fire with this sophisticated device. It is presumable that AFDD manufacturers use different algorithms and indicators in arc detection and the development is still going on. Comprehensive descriptions of
©2018 IEEE Electromagnetic Compatibility Magazine – Volume 7 – Quarter 4
algorithms, arc indicators and operation principles can be found from [3] - [7]. Typical characteristics for arcing are: • high-frequency noise in voltage and current • amplitude variations in current and changes in rate of rise of current • rectangular shape of voltage waveform • “shoulders” in current waveform. As the one of the characteristics is the high frequency noise, which is measured in the MHz range in AFDD [7], it is possible that the electrical installation protected by AFDD is susceptible to RF transmissions and unwanted tripping may occur. This has actually happened in U.S. in radio amateur stations [8]. Military installations have typically several RF transmitters and therefore it is very important to evaluate the RF susceptibility of AFDDs in addition to evaluation of emission characteristics.
II. Test Set-Up A. Test installation AFDD sample products were installed into a small non-conductive plastic enclosure one at the time using DIN rail connection. The AC power inlet and outlet cables of the enclosure were made from unshielded H05VV-F PVC cable. The inlet cable had standard Schuko plug and the outlet cables had standard Schuko outlet sockets. Schuko plug on inlet cable was selected as the Line Impedance Stabilization Network (LISN) output was equipped with Schuko outlet socket. Schuko outlets were selected to quick connect loads. The test installation with cable lengths is shown in Fig. 1.
Fig. 2. Test set-up in semi-anechoic chamber during emission measurements.
The cable lengths and the orientation of the cables were selected according to test surface dimensions and test antenna patterns. In real life, for example in command post shelters, the cable lengths are much longer and the cabling has both horizontal and vertical runs. As the cabling was laid on horizontal surface it is probable that the maximum emission and susceptibility occurs on horizontal antenna polarization.
III. Emission Measurements A. Conducted emissions Conducted emission measurements were performed according to requirement CE102 of MIL-STD-461G standard [9]. Measurement parameters were according to the standard. During all emission measurements, both conducted and radiated, the loads were disconnected as the preliminary measurements showed that the load has no impact on the emission level of the AFDD. The measurement results for five product samples are shown in Fig. 3 and Fig. 4. The limit line applied is the CE102 limit for all applications with supply voltage equal or higher than 220 V.
Fig. 1. Test installation used in the testing.
B. Test set-up in semi-anechoic chamber The tests were performed in a semi-anechoic chamber. The test installation was laid on non-conductive wooden surface and the test installation was made by using unshielded cables and nonconductive enclosure as described earlier to maximize the emissions and susceptibility. This set-up shown in Fig. 2 does not represent typical installation in a military environment but the purpose of the set-up was to get the worst case results. It is obvious that shielded cables and conductive enclosure bonded to conductive surface would give better results.
Fig. 3. Conducted emission measurement results from line (L).
©2018 IEEE Electromagnetic Compatibility Magazine – Volume 7 – Quarter 4
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Fig. 4. Conducted emission measurement results from neutral (N).
Fig. 6. Radiated emission measurement results, horizontal polarization.
All measured sample products fulfilled CE102 requirement but there were significant differences in results between measured products, even 50 dB differences were measured. Probably the main interference source is the switch-mode power supply inside AFDD. Different switching frequencies and different types of switch-mode power supplies may be behind the differences in measurement results.
levels on frequencies between 70 MHz to 200 MHz exceeded the limit line in two cases. Still the emission levels were quite moderate and all products probably clearly fulfil the civilian IEC and EN standard emission requirements for radiated emissions.
B. Radiated emissions Radiated emission measurements were performed according to requirement RE102 of MIL-STD-461G standard. Measurement frequency range was 10 kHz to 18 GHz when vertical antenna polarization was used and 30 MHz to 18 GHz when horizontal antenna polarization was used. All measurement parameters were according to the MIL-STD-461G standard. Measurement results showed that above 1 GHz frequency the radiated interference didn’t deviate from the ambient. This applied to all of the measured sample products. Therefore highest frequency in Fig. 5 and Fig. 6 is 1 GHz. The limit line applied is the limit for Army, Ground applications. As predicted earlier, the highest radiated emission levels were measured with horizontal antenna polarization. Highest emission
The frequency range where the highest emissions were measured could be a result from the used cable lengths. Shorter or longer cables may move the emission peaks to other position in the frequency domain. Cable lengths may also have an effect to interference amplitudes. These above mentioned facts should be taken into account AFDD installations and measurements in installations e.g. in command post shelters should be done in the future with on-board antennas.
IV. Radiated Susceptibility Testing A. MIL-STD-461G RS103 tests Radiated susceptibility tests were performed according to requirement RS103 of MIL-STD-461G standard. The test frequencies were limited to the tactical VHF band (30 MHz to 88 MHz) and NATO UHF band (225 MHz to 400 MHz) which are commonly used in military land applications. Testing on HF band (3 MHz to 30 MHz) would also be interesting, but due to the testing equipment limitations this was not possible. Susceptibility to HF transmissions should be tested in the future in real life installation. The electric field strength used in testing was 20 V/m on tactical VHF band and 50 V/m on NATO UHF band. These field strength values were trade-off between test equipment limitations and the realistic maximum field strength values inside a mobile shelter or building. The modulation was pulse modulation (1 kHz, 50 %) as required by MIL-STD-461G. Fig. 7 shows the test set-up during radiated susceptibility testing. Two halogen lights were connected to the test installation as loads and indicators for unwanted tripping. The test set-up was monitored with CCTV camera system during testing.
Fig. 5. Radiated emission measurement results, vertical polarization.
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The result of RS103 tests was that only one AFDD was susceptible to the applied field strengths. The sample product #5 tripped on frequen-
©2018 IEEE Electromagnetic Compatibility Magazine – Volume 7 – Quarter 4
emission levels in practice. Still this device is another new potential interference source. The immunity against RF fields was better than expected, only one sample product tripped unintentionally. The shielded cables and enclosures will increase the immunity in real world installations, so the assumption is that the radiated susceptibility of the AFDD will not be a problem.
Fig. 7. Radiated susceptibility testing with halogen lights as a load.
As proposed earlier the further testing in real world installations like in command post shelters is needed in the future. Especially testing with installations having high power HF transmitters is needed.
cies between 230 MHz and 261 MHz when the test field strength was approximately 50 V/m and the horizontal polarization was used. Unwanted tripping did not occur when the test was repeated with lower field strengths or with vertical polarization. Unwanted tripping required couple seconds RF field illumination time.
Acknowledgment
B. Testing with tactical military VHF radio transmission (VHF radio test)
References
I would like to thank our EMC test specialist Mr. Tommi Seppälä for the support in the testing and the local distributors for providing AFDD samples.
1. IEC 62606 Ed. 1 “General requirements for Arc Fault Detection Devices”, March 2013. 2. UL 1699 “Arc Fault Circuit Interrupters“, Release Feb 11th 2011, © Underwriters Laboratories Inc. 3. G. D. Gregory and G. Scott, “The arc-fault circuit interrupter: an emerging product,” IEEE Transactions on Industry Applications., vol. 34, pp. 928–933, Sept. /Oct. 1998. 4. G. D. Gregory, K. Wong, and R. F. Dvorak, “More About Arc-Fault Circuit Interrupters,” IEEE Transactions on Industry Applications, vol. 40, no. 4, pp. 1006–1011, July/Aug. 2004. 5. G. Artale et. al. “A set of indicators for arc faults detection based on low freIn this test a tactical VHF radio with a vehicle power amplifier (50 W) quency harmonic analysis,” Proceedings of IEEE International Instrumentation was connected to the same test antenna as used in the RS103 test. The and Measurement Technology Conference (I2MTC), 2016. measured field strength in this test was between 16 V/m to 18 V/m. 6. G. Artale et. al. “Arc Fault Detection Method Based on CZT Low-Frequency Harmonic Current Analysis,” IEEE Transactions on Instrumentation and Measurement, vol. 66, issue 5, pp. 888–896, May 2017. Unwanted tripping of AFDD’s was not detected during these tests. 7. Technology Primer - Siemens 5SM6 AFD units, [Online]. Available: https://cache. industry.siemens.com/dl/files/288/109482288/att_870494/v1/5SM6-AFD-units--Primer_4882_201603081324574123.pdf, Accessed on: May. 17, 2018. 8. ARRL Helps Manufacturer to Resolve Arc Fault Circuit Interrupter RFI Problems, SummaryTHIS of test results [Online]. Available: http://www.arrl.org/news/arrl-helps-manufacturer-to>V.REPLACE LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 4 resolve-arc-fault-circuit-interrupter. Accessed on: Jan. 4, 2017. 9. MIL-STD-461G. Department of Defense Interface Standard. Requirements for Table II summarizes the test results of performed tests. the of Electromagnetic Interference Characteristics of Subsystems and TABLE II [8]Control ARRL Helps Manufacturer to Resolve Arc Fault Circuit Interrupter Equipment. 2015.[Online]. Available: http://www.arrl.org/news/arrlSUMMARY OF THE TEST RESULTS RFIDecember Problems, helps-manufacturer-to-resolve-arc-fault-circuit-interrupter. Accessed VHF radio Product CE102 RE102 RS103 on: Jan. 4, 2017. test [9] MIL-STD-461G. Department of Defense Interface Standard. Biography 1 Pass Fail Pass Pass Requirements for the Control of Electromagnetic Interference 2 Pass Pass Pass Pass Characteristics of Subsystems and Equipment. December 2015. 3 Pass Pass Pass Pass Janne Pulkkinen received the B.Sc. (Tech) degree 4 Pass Pass Pass Pass from the Tampere University of Applied Sciences, 5 Pass Fail Fail Pass
In addition to the MIL-STD-461G RS103 test the test installation was illuminated with real tactical VHF transmission on frequency range of 30 MHz to 88 MHz. The detailed parameters of this anti-jamming frequency hopping transmission are classified information.
VI. Conclusions
VI. CONCLUSIONS
Finland, in 2002, and the M.Sc. (Tech), and Lic.Sc. (Tech)Janne degrees from the Tampere Universitythe of B.Sc. Pulkkinen received Technology, in 2006, and 2013, the respective(Tech)Finland, degree from Tampere ly. Since 2015, he is aofSystem Engineer in C4ISRFinland, University Applied Sciences, Systems Division in Joint Systems of Finnish in 2002,Centre and the M.Sc.Defence (Tech),Forces, and Lic.Sc. Tampere, Finland. From 2004 to 2015 he was with from Army Materiel (Tech) degrees the ComTampere mand Headquarters, serving in various positions. From 2001 toFinland, 2004 he in University of Technology, was a Design and Test Engineer the2013, defence industry. His research 2006, in and respectively. Since 2015, interests include electromagnetic compatibility of military equipment he is a System Engineer in C4ISR Systems and especiallyinmilitary measurements Division Joint systems, Systemsincluding Centrerelated of Finnish Defenceand Forces, testing. Mr. Pulkkinen Member of MATINE Scientific Tampere, Finland.is aFrom 2004 to 2015(Finnish he was with Army Advisory Board for Defence) Electronics serving Chapter. in various positions. Materiel Command Headquarters,
The outcome of emission the emission measurements was quite The outcome of the measurements was quite close to close waswas expected. As an active the AFDD towhat what expected. As anelectronic active device electronic device the causescauses conducted and radiated which should be taken AFDD conducted and emissions radiated emissions which should account in military applications whereapplications low background noise low beintotaken into account in military where level is required. This is a new requirement legacy background noise level is required. Thiscompared is a newtorequirement safety devices such assafety circuit devices breakers such or residual current devices. or compared to legacy as circuit breakers Measured emission levels were quite moderate shielded cables residual current devices. Measured emissionand levels were quite and enclosures in real military installations will probably reduce the moderate and shielded cables and enclosures in real military installations will probably reduce the emission levels in From 2001 to 2004 he was a Design and Test Engineer in the practice. Still this device is another new interference ©2018 IEEEpotential Electromagnetic Compatibilitydefence Magazine – Volume 7 – Quarter 4 industry. His research interests include 49 source. electromagnetic compatibility of military equipment and
