Iec tr 61000 1 3 2002

FOREWORD ...4 INTRODUCTION ...6 1 Scope ...7 2 Reference documents ...7 3 Definitions ...7 4 General considerations ...9 5 Overview of effects experience ...10 5.1 Atmospheric testing in

Atmospheric testing introduction

During atmospheric nuclear testing, unusual electrical effects were observed, notably by Enrico Fermi, who first reported these phenomena occurring at significant distances from the blast Different types of electromagnetic pulses (EMP) are generated based on the burst height, with high-altitude EMP (HEMP) being particularly significant due to its extensive range of effects.

EMP occurs when the nuclear detonation is higher than an approximate altitude of 30 km above the earth's surface.

The United States and the Soviet Union conducted a limited number of high-altitude nuclear tests, primarily the U.S Starfish event over Johnston Island and three Soviet tests in Kazakhstan in 1962 These tests, totaling around ten, primarily resulted in unintended effects on civil electronics, including malfunctions and damage, which were later analyzed to confirm their connection to the nuclear tests.

In the following clauses, several effects will be reviewed from the US high-altitude test series in

In 1962, issues were identified in the input circuits of radio receivers, and surge arresters on aircraft with trailing wire antennas activated unexpectedly Notably, 30 strings of streetlights failed simultaneously during the Starfish experiment, with the streetlight incident being the most thoroughly documented and analyzed, which will be further discussed in section 6.1.

In the fall of 1962, the Soviet Union experienced significant failures in various long-line systems, particularly in power and telecommunications Notably, the protection devices on a 500-km-long telecom line failed, a situation that has been thoroughly documented and analyzed.

Simulator testing introduction

Since the late 1960s, more than 10 countries have developed HEMP simulators to generate controlled transient electromagnetic (EM) fields within a specified test volume, as outlined in IEC 61000-4-32 The primary goal of these simulators is to assess the immunity and susceptibility of various equipment and systems to HEMP disturbances.

While the HEMP waveforms that are produced in the various simulators have some variation in their waveform characteristics, the standardized electric field waveform today is described as a

2,5/25 ns waveform with an amplitude of 50 kV/m (IEC 61000-2-9).

HEMP simulators can effectively represent electric and magnetic field transient pulses within a limited area; however, they fall short of replicating the true nature of HEMP, which is characterized by a plane wave field that remains consistent over vast distances, often spanning tens of kilometers As the fields propagate from the pulser, they encounter losses, leading to accurate behavior only within test volumes that range from a few to several meters Additionally, since no simulator can capture the full spectrum of field polarizations and angles of incidence at the Earth's surface, the immunity tests conducted with these simulators yield incomplete results.

Testing system cables, particularly those connected to Power over Ethernet (PoE), poses significant challenges during HEMP simulator field tests Therefore, it is essential to conduct environment tests specifically designed for conductive PoEs to ensure accurate results.

IEC 61000-2-10, for example), and results of these types of tests are also described in this technical report.

5 Figures in square brackets refer to the bibliography.

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This technical report primarily focuses on civil electronic and power-line equipment testing in HEMP field simulators, rather than military equipment It presents the results of five well-documented sets of experiments, detailed in sections 7.1 to 7.5.

This technical report will examine the experiences from conducted testing, with a focus on recent insights related to high-voltage power-line equipment testing as outlined in clause 8.

United States atmospheric test experience – Starfish test

On July 8, 1962, at around 11:00 p.m Hawaiian local time, the Starfish nuclear device, yielding approximately 1 megaton, was detonated approximately 400 kilometers above Johnston Atoll.

Hawaiian Island of Oahu was approximately 1 400 km See figure 1 for a more detailed description of the geometry of the burst.

Figure 2 presents the headline on the front page of the New York Tribune, European Edition

The U.S conducted an atomic blast 200 miles over the Pacific, hailed as “probably the most grandiose military-scientific experiment in history.” This test produced spectacular space fireworks visible for thousands of miles, lasting six minutes In Hawaii, observers witnessed a dazzling white burst followed by a spectrum of colors, including greens, brilliant yellows, oranges, and deep reds Aurora lights were reported in Samoa, 2,000 miles south, and New Zealand, 4,000 miles away, attributed to the release of space radiation particles from the Van Allen belts The Atomic Energy Commission was involved in this significant event.

States reported that two satellites were in orbit to record the effects of the blast.

In terms of the electromagnetic effects that were reported, the New York Tribune article mentions the following items:

− Radio communications were blacked out for times up to 30 min due to ionospheric disruptions.

The Geodetic Survey in Honolulu recorded a significant deviation in the geomagnetic field at the moment of detonation, which was followed by five to six minutes of heightened activity before gradually returning to normal within approximately 30 minutes This sudden impulse exceeded the expectations of local scientists.

During a test shot in Hawaii, burglar alarms and air-raid sirens were triggered, and there were unusual electrical malfunctions with some streetlights turning off while others illuminated No immediate explanation was provided for these incidents.

Following the test, local Honolulu newspapers reported that streetlights across various areas of Oahu had gone dark during the event The Honolulu Star-Bulletin highlighted these incidents.

On July 9, 1962, it was reported that the City-County Street Lighting Department attributed the failure of several fuses on the Island to shock waves from the Johnston Island nuclear blast Some accounts noted that 30 strings of lights were affected This information is based on a technical report by Dr Charles Vittitoe from 1989, which examined one of the specific circuits that experienced failure.

The Vittitoe findings indicate that the estimated incident peak HEMP electric field of 5.6 kV/m generated enough current in the lighting circuit to damage a disk cut-out in the secondary of an isolation transformer This transformer, rated at 4 kV, has a disk cutout failure threshold of up to 1,200 V at 60 Hz Vittitoe estimated that for a HEMP-induced voltage waveform, the failure level could be five times greater.

The operating current was measured at 6.6 A, with failure anticipated to start at 14 A Additionally, the calculated common mode current induced by HEMP was found to be 140 A Vittitoe determined that the HEMP fields and the resulting induced currents aligned with the observed failures.

The polarization of the incident HEMP fields, combined with the various orientations of lighting circuits, leads to significant variations in the induced currents across different circuits This phenomenon accounts for the selective failure of certain Hawaiian lighting circuits during the Starfish test.

Burst 30 km SW of J.A. at 16° 28’ N, 169° 38’ W

Figure 1 – Starfish-Honolulu burst geometry, with the X indicating the location of Johnston Atoll

On July 9, the United States conducted a monumental military-scientific experiment by detonating a hydrogen explosion 200 miles above Johnston Island in the South Pacific This event is considered one of the most significant in history, with energy output surpassing that of previous nuclear tests.

1 m il on tons of TN l i , triggered T spect cul a r space fireworks over a thousands of mi es for 6 minu es l start g at 11 i 00 p n : m l st n a ght, i Hawai an t i me (0900 GM i Monday).

Hawaii, located 750 miles northwest of Johnston Atoll, experienced a stunning white burst followed by vibrant surges of nearly all the colors of the rainbow, including greens, brilliant yellows, rich oranges, and glowing blood reds.

Curt ns of a i urora li a hts were g report d at Somoa, 2000 mil s e south o f t e test h si e t

A red glow appeared on the northern horizon in New Zealand, spreading across the sky and illuminating the sea with vibrant colors This phenomenon may have been triggered by the release of space radiation, typically contained within the Van Allen belts surrounding the Earth.

Figure 2 – Front page of New York Tribune , European Edition, 10 July 1962

The images may lack quality, but the upper night-time photo captures Diamond Head and Waikiki in Honolulu just moments before the test shot, while the lower image, taken shortly after, reveals a bright sky and ocean reflection.

Lamp Wire separation 14,5 inches (exaggerated on sketch)

Figure 3 – Ferdinand Street (Honolulu, Hawaii) series lighting system in 1962

Soviet Union atmospheric test experience

In 1962 the Soviet Union conducted a series of high-altitude nuclear tests over Kazakhstan.

In a presentation at the 1994 EUROEM Conference, Prof Vladimir Loborev, Director of the Central Institute of Physics and Technology, discussed the effects of High-Altitude Electromagnetic Pulse (HEMP) observed during a significant yield test conducted at a height of 300 km, illustrating his points with various examples.

− a long, radially oriented, above-ground communications line failed;

− a buried communications line more than 600 km away from ground zero failed;

− a power line insulator was damaged, resulting in a short circuit on the electrical line;

A detailed analysis was conducted on a specific telecom circuit using data from the test series to investigate the failure of the line's protective devices This above-ground telecom line spanned approximately 500 km, starting from a designated ground range.

The test involved a distance of 180 km at an azimuth of 90°, concluding at a ground range of 650 km with an azimuth of about 50° Each repeater element along the line, spaced several tens of kilometers apart, was equipped with gas-filled surge arresters and fuses Following the test, it was determined that all surge arresters activated and all fuses were damaged, necessitating repairs to the line.

The analysis in [6] computed the early-time electric fields of HEMP, illustrated in figures 4 and 5, where the phi component represents the transverse horizontal field and the theta component denotes the transverse vertical field It is important to note that the total transverse electric field remains relatively constant along the length of the line Additionally, figure 6 displays the computed late-time (MHD EMP) magnetic field for ground ranges of 433 km and 574 km, highlighting the variations in the magnetic field.

Geomagnetic storms typically exhibit values around 400 nT, but the rapid rise time illustrated in figure 6 leads to a significantly stronger late-time electric field Notably, the maximum rate of change of the incident magnetic field reaches approximately 1,800 nT/min, exceeding the derivative associated with the 1989 Hydro-Quebec power system collapse by more than four times.

Figure 4 – The amplitudes of the computed early-time HEMP E-field components versus time for the near end of the 500-km telecom line

Figure 5 – The amplitudes of the computed early-time HEMP E-field components versus time for the far end of the 500-km telecom line

Figure 6 – Computed transverse late-time HEMP magnetic flux density at the earth's surface at ground ranges of 433 km and 574 km from the surface zero point

The early-time High-Altitude Electromagnetic Pulse (HEMP) fields, measured at approximately 8 kV/m, were used to calculate the common mode load voltages and short-circuit currents on the telecom line, specifically for subline 2, an 80 km segment of the 500 km line The results, illustrated in figures 7 to 9, indicate that the induced early-time HEMP voltage reaches nearly 30 kV, sufficient to activate surge arresters as detailed in table 1 However, the calculated early-time currents remain below 100 A, which is not high enough to cause damage, as outlined in the accompanying table.

The computed late-time electric fields of around 10 V/km indicate that the peak-induced late-time voltage and current on the lines are approximately 400 V and 4 A, respectively, which are sufficient to short the fuses, as shown in Table 2 The authors in [6] suggested that the late-time HEMP fields likely caused the failures observed in the above-ground communications line.

The computed early-time HEMP load voltage over time for the far end of the 80-km long subline 2 is illustrated in Figure 7, with the top figure representing the earliest time and the bottom figure displaying a later time view.

The computed early-time High-altitude Electromagnetic Pulse (HEMP) short-circuit current is illustrated against time for the near end of the 80 km long subline 2 The top figure represents the earliest time, while the bottom figure provides a view at a later time.

The computed short-circuit current for the far end of the 80 km long subline 2 is illustrated in Figure 9, with the top figure representing the earliest time and the bottom figure displaying a later time view.

Table 1 – Data on the arrester firing voltage as a function of the voltage waveform characteristics (from [6])

Applied voltage characteristics Arrester firing voltage

3 Surge voltage for various pulse rise times ( à s) a) τ = 100 b) τ = 50 c) τ = 25 d) τ = 20 e) τ = 16 f) τ = 14 g) τ = 12 h) τ = 10 i) τ = 8 j) τ = 6 k) τ = 4 l) τ = 2

Table 2 – The peak pulse currents in kA damaging the fuse SN-1 (from [6])

7 HEMP simulator testing with radiated transients

This section reviews five sets of simulator experiments utilizing radiated fields Some experiments yield direct effects data for commercial equipment, while others validate coupling codes essential for confirming the accurate levels of conducted environments under actual High-Altitude Electromagnetic Pulse (HEMP) conditions The validated coupling codes are subsequently employed to calculate the necessary levels for conducted transient testing with HEMP direct-injection simulators (refer to clause 8).

Consumer electronics

In the late 1980s, 91 different examples of consumer electronics were tested with the FEMPS

The HEMP simulator provides insights into the potential effects of consumer electronics exposed to fast-rise HEMP fields Three peak field levels were tested: low (6.7 kV/m), medium (12.4 kV/m), and high (16.6 kV/m) Results indicate that even at a low field level of 6.7 kV/m, significant critical upsets were observed, with increased damage noted at the higher level of 16.6 kV/m.

Table 3 – Summary of operational observations at FEMPS [7]

Effects at various levels of testing

Test item type Test item

Low level Medium level High level

Television Emerson 13 in Critical upset Critical upset Failure

Portland 13 in Noncritical upset Critical upset Critical upset Zenith 19 in., SD1911W — Critical upset Critical upset

JC Penney 13 in — Noncritical upset Noncritical upset

Montgomery Ward 25 in — Critical upset Critical upset

VCR Akai VS515U Critical upset Critical upset Critical upset

Sharp Critical upset Critical upset Critical upset

Sears Critical upset Critical upset Critical upset

Symphonic Critical upset Failure Failure

Goldstar Noncritical upset Noncritical upset Noncritical upset

Mitsubishi HS348UR — Critical upset —

Magnavox VR9525AT — — Noncritical upset

Stereo receiver Kenwood Critical upset Critical upset Critical upset

Onkyo Noncritical upset Noncritical upset Noncritical upset

JVC — Critical upset Critical upset

Mobile radio Johnson 7171 uhf — Noncritical upset Noncritical upset

Johnson SDL6085, 16 channel — — Noncritical upset

GE PSX vhf — — Noncritical upset

Computer Leading Edge model D Critical upset Critical upset Failure

IBM PC AT Critical upset Critical upset —

Hayes 1200-baud modem — — Critical upset

CD player Sharp Noncritical upset Critical upset Critical upset

Cellular phone GE Critical upset — Critical upset

Telephone Realistic cordless Critical upset Critical upset Critical upset

Answering machine Phone mate Critical upset Critical upset Critical upset

Garage door opener Genie — Critical upset Critical upset

Medical equipment Kangaroo feeder pump Critical upset Critical upset Critical upset

Infant monitor — Critical upset Failure

Automobile radio Craig AM/FM cassette Noncritical upset Noncritical upset Noncritical upset

Satellite dish Realistic 8,5 ft Failure (not verified) — —

— Indicates no abnormal observation or the unit was not tested at that level because of a previous failure.

After testing at the FEMPS simulator, equipment was re-evaluated at the Woodbridge Research Facility for a 4 kV/m pulse with a slower rise time of approximately 5 ns Measurements of the induced current on various cables were conducted to analyze their levels and time behaviors, revealing maximum currents of around 10 A for the 4 kV/m electric field The waveforms exhibited damped sine behavior, and if the response is linear, peak currents could reach approximately 130 A for a 50 kV/m HEMP pulse However, arcing in connectors may reduce the coupled voltages and currents, highlighting the importance of testing at expected threat levels to accurately assess immunity levels.

Figure 10 – Time response for a typical antenna cable coupled current measured at WRF

Figure 11 – Time response for a typical telephone cable coupled current measured at WRF

Figure 12 – Time response for a typical power cable coupled current measured at WRF

Figure 13 – Time response for a typical speaker wire coupled current measured at WRF

Figure 14 – Time response for a typical computer keyboard coupled current measured at WRF

Communication radios

One of the earliest studies of the performance of commercial electronics was published by Oak

Ridge National Laboratory by Barnes in 1974 [8] In this study, the ALECS HEMP simulator at

Kirtland Air Force Base in New Mexico served as the testing ground for various radio equipment and antennas utilized in land mobile, amateur, citizens', and commercial broadcast band radio systems The High-Altitude Electromagnetic Pulse (HEMP) field exhibited a pulse rise time ranging from 4 nanoseconds to 10 nanoseconds, with a pulse decay duration of about 500 nanoseconds.

During testing, peak field levels ranging from 5 kV/m to 200 kV/m were utilized It is important to highlight that the mobile units were not linked to commercial power lines during this process, suggesting that the measured threshold levels might have been lower if they had been connected to power sources.

Table 4 displays the results of the test series, indicating the failure thresholds or susceptibility levels as a range of field levels due to discrete testing settings For instance, the citizens' band "walkie talkie" (test object 2) failed between 5 kV/m and 10 kV/m, with the 5 kV/m test showing no issues, while the 10 kV/m test resulted in a failure of the RF transistor This suggests that the actual failure threshold may be lower than 10 kV/m.

10 kV/m) is shown in the table.

A detailed examination of the table reveals that 10 out of 13 test objects successfully withstood electric fields below 50 kV/m, which aligns with the IEC standard for early-time High-Altitude Electromagnetic Pulse (HEMP).

IEC 61000-2-9 highlights a positive development; however, the radios examined did not utilize the low-voltage integrated circuits prevalent in today's technology Additionally, there is a lack of publicly available data regarding the performance of contemporary cellular phones in response to HEMP transient fields.

Frequency Manufacturer Threshold failure Obvious Damaged

No Class and type band and model Receiver type level Ef (kV/m) malfunctions components

1 Amateur base 20 m Hallicrafters Co Tube 100 < Ef None Not checked receiver Model S-40B

2 Citizens' band 11 m Courier Transistor 5 < Ef < 10 No reception RF transistor walkie talkie Model CWT-30

3 Citizens' band 11 m Courier Transistor 10 < Ef < 20 No reception RF transistor walkie talkie Model CWT-30

4 Land mobile VHF Motorola Hybrid tube 30 < Ef < 100 No tuning coils, RF

Public safety Low band HT 21-16 and transistor transmission transistor, and power

5 Land mobile VHF Motorola Tube 50 < Ef < 100 Non-operational* Antenna matching

Public safety Low band T41GGV circuits, tuning

Mobile unit coils, and wiring

6 Land mobile VHF Motorola Transistor, and 100 < Ef < 200 No reception RF transistor

Public safety High band HT 220 integrated circuit walkie talkie

7 Land mobile VHF Motorola Transistor and 70 < Ef < 100 No audio-integrated

Public safety High band HT Radiophone an integrated circuit transmission circuit

8 Land mobile VHF Motorola Transistor and 100 < Ef None No damage

Public safety High band Motrac HHT Series integrated circuit

9 Land mobile VHF General Electric Tube 100 < Ef None No damage

Public safety High band ET 35A, ET 35B 9 dB gain antenna

10 Land mobile UHF Motorola Transistor 100 < Ef None No damage

Table 4 – Summary of information on radios tested (concluded)

Frequency Manufacturer Threshold failure Obvious Damaged

No Class and type band and model Receiver type level Ef (kV/m) malfunctions components

11 Land mobile UHF Motorola Transistor 100 < Ef None No damage

Industrial Motrac service MHT Series

12 Commercial radio AM broadcast Realtone 2424 Transistor 400 < Ef < 500 Weak reception RF transistor

13 Commercial radio FM broadcast Realtone 2424 Transistor 400 < Ef < 500 Little or no Oscillator reception transistor

* Observed non-operational during the post-test equipment check.

Commercial power lines

In 1998, Imposimato et al conducted an EMP coupling experiment to investigate the effects of HEMP fields generated by the Italian CISAM simulator on a realistic medium voltage (MV) power line, including transformers The HEMP simulator utilized a guided wave design in a wedge-shaped geometry, achieving a peak vertical electric field of 50 kV/m within the test volume.

The experiment aimed to measure the currents and voltages induced on power lines and transformers, with a focus on the geometry of exposure illustrated in figure 15 The three-wire power line is positioned transversely to the field propagation in the simulator, and the horizontal electric fields intensify as the power line moves away from the simulator's centerline, with fields oriented in opposite directions Despite the seemingly unfavorable orientation for simulating the incident plane-wave HEMP field, the horizontal electric fields achieved a peak value of 20 kV/m near the simulator's edges.

The HEMP field variations along the power line were meticulously analyzed and modeled, leading to a comparison of the measured and calculated voltages, approximately 350 kV, as illustrated in figure 16 This strong correlation is crucial for the study.

HEMP effects require analysis to assess the current levels during their occurrence As illustrated in figure 17, coupled currents peak at 600 A near the simulator edges but drop to 200 A at location Q (4) due to ground losses and the absence of a driving HEMP field in that area.

Figure 15 – Geometry of the medium voltage (MV) power lines with respect to the EMP simulator

Figure 16 – Comparison of measured (left) and calculated (right)

HEMP simulator-induced voltage (line to ground) at position M in figure 15, where the line turns 90°

Figure 17 – Comparison of the measured currents in amperes at four different locations:

1 and 2 at 48 m on either side of the simulator centreline (points M and N in figure 15), and 3 and 4 near the far end of the line (near point Q in figure 15)

The experiment demonstrated that a non-plane-wave HEMP field at 20 kV/m can induce voltages close to 400 kV and generate currents up to 600 A in a three-wire power line loaded at both ends with its characteristic impedance Furthermore, the long-line coupling model proved to be highly accurate for this complex geometry, confirming its suitability for evaluating HEMP effects.

Train power-line coupling experiment

A power line was positioned directly above a set of rail lines and impedance-matched at both ends, with a real locomotive placed at the center of the rails Additionally, a hybrid HEMP simulator, located 20 meters away, generated a horizontally polarized electromagnetic field similar to that of the old Bell Laboratory.

HEMP waveform [10] at the locomotive The waveform characteristics were:

− fall-time to half-amplitude about 200 ns;

− electric field peak value about 50 kV/m;

− line height over the ground 5 m.

A perfect conducting ground was approximately represented by the rails of the locomotive; this assumption was used for the calculations done as part of the evaluations [11].

Figure 18 – Geometry for HEMP simulation test of locomotive with single power line

The measured current induced in the overhead wire at x = -7 m, directly above the left end of the locomotive, reached an amplitude of 272 A with a rise time of approximately 20 ns, posing potential risks to the train's electrical and electronic systems This level, while not the worst-case scenario due to geometric factors, allows for the establishment of a current injection procedure to facilitate testing of equipment connected to the railway power system It is crucial to develop methods to mitigate HEMP-induced currents and voltages to prevent damage or malfunction within the train system Notably, during the radiated HEMP experiment, the locomotive encountered issues that necessitated corrections, particularly as the control electronics (TTL/CMOS) were disrupted by the induced currents, leading to the cessation of wheel movement and potentially halting a moving locomotive.

Figure 19 – Measured HEMP-induced current on power line directly above left end of locomotive

HEMP-induced currents on a three-phase line

A three-phase line is open-circuited at both ends, with a fourth grounding wire connected to the ground at each extremity This setup is positioned 10 meters in front of a hybrid HEMP simulator, as illustrated in figure 20 Although this configuration may lack realism, the primary objective of the experiment was to validate the code and data.

The HEMP simulator produces a horizontally polarized electromagnetic field having the following characteristics:

A perfectly conducting ground was approximately simulated by metallic plates, about 3 m wide, under the line.

(The elliptical line shown is the simulator conductor and the terminating resistors at the ground are not shown.)

Figure 20 – Geometry for three-phase line placed under a hybrid HEMP simulator

The measured induced current in the grounding wire (solid line) is compared to a calculation using Agrawal's transmission line model [13] as indicated in figure 21.

Figure 22 illustrates the current in the center of a single open-circuited phase wire, with the grounding wire removed The peak current is approximately equal to that of the grounding wire current, measuring 240 A compared to 275 A However, the damping of the waveform is significantly slower in the open-circuit condition of the phase line than in the short-circuit condition of the ground wire.

This experiment demonstrates a clear understanding of the coupling of High-Altitude Electromagnetic Pulse (HEMP) fields to long lines, which can be accurately predicted using current computer models This finding aligns with conclusions from atmospheric nuclear test experiments that revealed unexpected effects without direct measurements Consequently, it has been essential to calculate the conducted transients responsible for the observed system impacts.

Figure 21 – Comparison of measured (solid line) and calculated (dashed line) currents flowing on the shielding wire

Figure 22 – HEMP current measured in the centre of one of the open-circuited phase wires when the grounding wire was removed

8 HEMP simulator testing with conducted transients

High-voltage power-line equipment

Scientists in Russia conducted extensive HEMP tests on power lines to assess the impact of high-altitude nuclear bursts Early experiments revealed that insulators on 110 kV power lines could typically endure HEMP open-circuit voltage pulses around 400 kV, although some porcelain insulators did fail However, when the same 400 kV test was applied to energized power lines, it led to sparkover, flashover, and insulator failures at approximately 350 kV Notably, the peak HEMP-induced voltage of 400 kV is significantly lower than the maximum HEMP threat of 1.6 MV, as outlined in IEC 61000-2-10.

To ensure accurate results, it is crucial to conduct tests in a realistic manner, as illustrated in figure 24 Alongside line insulators, tests were also carried out on high-voltage equipment, including valve and tube dischargers, shield gaps, and non-linear resistors The findings revealed that these protective measures are often inadequate and fail to provide sufficient protection against HEMP effects Additionally, breakdowns were observed in the low-voltage windings of 400 kV high-voltage transformers, as shown in figure 25 Furthermore, experiments indicated that mobile diesel power stations are also susceptible to HEMP effects, particularly when currents are induced in their supply power cables, as depicted in figure 26.

Historically, the focus on High-Altitude Electromagnetic Pulse (HEMP) effects was primarily on military needs, as military systems operated independently of the public power grid, utilizing locally generated power There was limited evidence suggesting that power systems were susceptible to HEMP, leading to a greater emphasis on studying telecom and radio systems However, recent findings from Russian experiences indicate that high-voltage power systems lacking special protective measures may indeed be vulnerable Furthermore, these power systems can effectively transfer HEMP energy into buildings, potentially causing additional damage to connected equipment A sample test setup for conducting these tests is illustrated in the accompanying figures.

and 4 near the far end of the line (near point Q in figure 15)

The experiment demonstrated that a non-plane-wave High-Altitude Electromagnetic Pulse (HEMP) field at 20 kV/m can induce voltages close to 400 kV and generate currents up to 600 A in a realistic three-wire power line, particularly when the line is loaded at both ends with its characteristic impedance Furthermore, the long-line coupling model proved to be highly accurate for this complex geometry, confirming its suitability for evaluating HEMP effects.

7.4 Train power-line coupling experiment

A power line was positioned directly above a set of rail lines and impedance-matched at both ends, with a real locomotive placed on the rails at the center Additionally, a hybrid HEMP simulator was situated 20 meters away, generating a horizontally polarized electromagnetic field similar to that of the old Bell Laboratory.

HEMP waveform [10] at the locomotive The waveform characteristics were:

− fall-time to half-amplitude about 200 ns;

− electric field peak value about 50 kV/m;

A perfect conducting ground was approximately represented by the rails of the locomotive; this assumption was used for the calculations done as part of the evaluations [11].

Figure 18 – Geometry for HEMP simulation test of locomotive with single power line

The induced current measured at x = -7 m, directly above the left end of the locomotive, reached an amplitude of 272 A with a rise time of approximately 20 ns, posing potential risks to the train's electrical and electronic systems This level of current, while not the worst-case scenario due to geometric factors, allows for the establishment of a current injection procedure to facilitate testing of equipment connected to the railway power system It is crucial to develop methods to mitigate HEMP-induced currents and voltages to prevent damage or malfunction within the train system Notably, during the radiated HEMP experiment, the locomotive experienced issues that necessitated corrections, particularly as the HEMP-induced currents confused the locomotive's control electronics (TTL/CMOS), leading to the wheels ceasing to turn, which could halt a moving locomotive.

Figure 19 – Measured HEMP-induced current on power line directly above left end of locomotive

7.5 HEMP-induced currents on a three-phase line

A three-phase line is open-circuited at both ends, with a fourth grounding wire connected to the ground at each extremity This setup is positioned 10 meters in front of a hybrid HEMP simulator, as illustrated in figure 20 Although this configuration may lack realism, the primary objective of the experiment was to validate the code and data.

The HEMP simulator produces a horizontally polarized electromagnetic field having the following characteristics:

A perfectly conducting ground was approximately simulated by metallic plates, about 3 m wide, under the line.

(The elliptical line shown is the simulator conductor and the terminating resistors at the ground are not shown.)

Figure 20 – Geometry for three-phase line placed under a hybrid HEMP simulator

The measured induced current in the grounding wire (solid line) is compared to a calculation using Agrawal's transmission line model [13] as indicated in figure 21.

Figure 22 illustrates the current in the center of a single open-circuited phase wire, with the grounding wire removed The peak current is approximately equal to that of the grounding wire current, measuring 240 A compared to 275 A However, the waveform's damping is significantly slower in the open-circuit condition of the phase line than in the short-circuit condition of the ground wire.

This experiment demonstrates a clear understanding of the coupling of High-Altitude Electromagnetic Pulse (HEMP) fields to long lines, which can be accurately predicted using current computer models This finding aligns with conclusions drawn from atmospheric nuclear test experiments, where unexpected effects occurred without measurements Consequently, it has been essential to calculate the conducted transients responsible for the observed system effects in these instances.

Figure 21 – Comparison of measured (solid line) and calculated (dashed line) currents flowing on the shielding wire

Figure 22 – HEMP current measured in the centre of one of the open-circuited phase wires when the grounding wire was removed

8 HEMP simulator testing with conducted transients

8.1 High-voltage power-line equipment

Scientists in Russia conducted extensive HEMP tests on power lines to assess the impact of high-altitude nuclear bursts Early experiments revealed that 110 kV power line insulators could typically endure HEMP open-circuit voltage pulses around 400 kV, although some porcelain insulators occasionally failed However, when the same 400 kV test was applied to energized power lines, it led to sparkover, flashover, and insulator failures at approximately 350 kV Notably, the peak HEMP-induced voltage of 400 kV on above-ground power lines is significantly lower than the maximum HEMP threat of 1.6 MV, as outlined in IEC 61000-2-10.

To ensure accurate results, it is crucial to conduct tests in a realistic manner, as illustrated in figure 24 Alongside line insulators, tests were also carried out on various high-voltage equipment, including valve and tube dischargers, shield gaps, and non-linear resistors The findings revealed that these protective measures often lack the necessary speed to effectively shield equipment from HEMP effects Additionally, breakdowns were observed in the low-voltage windings of 400 kV high-voltage transformers, as shown in figure 25 Furthermore, experiments indicated that mobile diesel power stations are also susceptible to HEMP effects, particularly when currents are induced in their supply power cables, as depicted in figure 26.

Historically, the focus on High-Altitude Electromagnetic Pulse (HEMP) effects was primarily driven by military needs, as military systems operated independently of the public power grid Consequently, there was limited evidence regarding the vulnerability of power systems to HEMP, leading to a greater emphasis on telecom and radio systems However, recent findings from Russian experiences indicate that high-voltage power systems lacking protective measures may indeed be susceptible to HEMP Furthermore, these power systems can effectively transmit HEMP energy into buildings, potentially causing additional damage to connected equipment A sample test setup for these evaluations is illustrated in the accompanying figures.

8.2 Testing of distribution transformers to conducted HEMP transients

Nineteen standard commercial distribution transformers, rated at 7.2 kV and 25 kVA, were tested to assess the vulnerability of their insulation systems to fast-rising conducted transients akin to High-Altitude Electromagnetic Pulse (HEMP) The testing utilized a waveform generator capable of producing peak open-circuit voltages of 400 kV.

The study involved testing voltages of 500 kV, 800 kV, and 1,000 kV, characterized by a rise time of 60 ns and a pulse width of 2,000 ns To accurately simulate realistic conditions, a 400-ohm series resistor was employed to represent the distribution-line surge impedance during voltage injection into a transformer.

Standard lightning impulse tests were conducted on distribution transformers to ensure insulation integrity before and after injection testing This process aimed to identify any insulation failures that may have occurred during the tests Additionally, failed transformers were disassembled for a thorough evaluation of their failure modes Notably, all injection testing was performed with the transformers de-energized.

The study involved 19 pole-mount single-phase distribution transformers, each featuring high-voltage windings rated at 12,470Y/7,200 V and a basic insulation level (BIL) of 95 kV While the majority of these transformers were equipped with single bushings, a few included double bushings All low-voltage windings were standardized at 120/240 V.

The transformers were evaluated in groups based on specific features Six units, labeled ZS1-ZS6, were single high-voltage bushing models without surge arresters Additionally, four units were fully self-protected, each equipped with a single high-voltage bushing and an externally gapped silicon carbide surge arrester.

The article discusses various configurations of self-protected units, specifically highlighting four units (ZV1-ZV4) that feature a single high-voltage bushing and a directly mounted gapped silicon carbide surge arrester (ZW1-ZW4) Additionally, it mentions two units (ZD1-ZD2) equipped with double high-voltage bushings but lacking surge arresters Furthermore, two completely self-protected units (ZE1-ZE2) are noted, which also have double high-voltage bushings and directly mounted gapped silicon carbide surge arresters.

Tiêu đề	Iec Tr 61000 1 3 2002
Trường học	International Electrotechnical Commission
Chuyên ngành	Electromagnetic Compatibility (EMC)
Thể loại	publication
Năm xuất bản	2002
Thành phố	Geneva

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Số trang	52
Dung lượng	1,69 MB