Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES

1. Voltage and Current Spikes & Transients -Power Supply Quality aspects for the AES Dr I.K. HatzilauProf., Hellenic Naval Academy (HNA) Dr J. ProusalidisAss. Prof, National Technical University of Athens [ NTUA ] Dr E. StyvaktakisHellenic Transmission System Operator [ HTSO ] E. SofrasPhD canditate, National Technical University of Athens [ NTUA ] Presented by I.K. Hatzilau1

2. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras What is the Scope of the Paper ? In this paper, … Initially, we present a short discussion on the characteristic parameters of the SPIKES and TRANSIENTS in Low Voltageshore and ship electric power networks. Then, we investigate, discuss and compare, the relevant continental and shipboard STANDARDS, with special attention given to a critical analysis of NATO Standard STANAG 1008 , in view of the expansion and the perspective of the AES technology. Presented by I.K. Hatzilau2

3. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras CONTENTS … the paper arrangement is the following :1. Introduction 2. Characterization parameters 3. Comparative analysis and evaluation of Shipboard Standards3.1 General overview of standards3.2. Military Standards ( STANAG 1008, USA-MIL-Std-1399)3.3. Particular aspects of AES4. Conclusion5. References Presented by I.K. Hatzilau3

4. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras CONTENTS … the paragraph3.2. Military Standards ( STANAG 1008, USA-MIL-Std-1399)… is the main contribution of the paper and here we discuss in detail the following items :3.2.a Spike peak limits3.2.b Spike waveshape, Test-impulse, Test-methode3.2.c Voltage/spike Transient Envelope3.2.d Voltage and current spikes3.2.eSeverity assessment of short duration variations [dips and swells] 3.2.f Supply Interruptions3.2.g Applicability of STANAG 1008 in fault conditions Presented by I.K. Hatzilau4

5. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 5. REFERENCES * It exists a large amount of paperson Spikes and Transients,but the huge majority of themrefers to continental power systems,with a big lack for shipboard systems.- A whole page of our paper has been dedicated for the enumeration of some of the most significant References. Presented by I.K. Hatzilau5

6. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 1. INTRODUCTION *Power Supply Quality (PSQ) is a term referringto a wide variety of disturbances in electric networks either ship or continental ones .* Electric networks suffer from “short time duration non-periodical disturbances”of voltage and current, caused by switching operations (making or breaking), short-circuits, fuse blowing-up, or even lightning strikes. Presented by I.K. Hatzilau6

7. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 1. INTRODUCTION   - The name of these disturbances varies depending on certain characteristics of them. Thus, terms like transients, spikes ( i.e.a transient of very short duration ), voltage surges, current surges,sags, dips, swells, etc are often met in relevant documents. Presented by I.K. Hatzilau7

8. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 1. INTRODUCTION Fig. 1 : Spikes introduced in AC power system during energization of : a PC-screen (4) and a PC-Terminal (8). .. Examples of measurements of spikes (shown in different time scales .. ) introduced in AC power system during energization: of a PC-screen (4) and of a PC-Terminal (8). Presented by I.K. Hatzilau8

9. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 1. INTRODUCTION Fig. 2 : Capacitor switching transient (EMTP simulation) Example: EMTP simulationof aCapacitor switching transient Presented by I.K. Hatzilau9

10. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 1. INTRODUCTION * Voltage and Current Spikes and Transients have several adverse consequences in shore and ship electric power networks,such as - equipment failure and - improper operation of the entire system (insulation breakdown, errors in data-processing equipment etc).* It is worth noting that these types of failuresare not often acknowledgedas consequences of power supply voltage or current surges. Presented by I.K. Hatzilau10

11. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS In the literature (including relevant standards)there has been a significant work on voltage (and current) surge issues in Low Voltage (LV) AC power systems[5–28], similar to ships ones.In IEEE 1159[6], which is one of the key-standards on PSQ, power electromagnetic phenomena are classified into 7 groups. Groups 1 and 2 are transients and short duration variations. like : ·Impulsive and oscillatory transientsand ·Voltage dips and swellsEach group is subdivided further into classes with specific characteristics, ….. as it can be seen in the next Table I. Presented by I.K. Hatzilau11

12. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS Table I : The Categorization of transients and short duration variations according to IEEE 1159 . Presented by I.K. Hatzilau12

13. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS What is anImpulsive transient and what is anoscillatory transient ?An impulsive transient is a sudden, non-power frequency change in voltage or current, or both, that is unidirectional in polarity. Lightning and switching actions are typical causes of impulsive transients.For an oscillatory transient the instantaneous values of voltage or current change polarity rapidly. Capacitor switching is the most common cause of such transients. It has been shown, that most voltage spikesin small-size Low-Voltage systems (like ship systems)are oscillatory transients. Presented by I.K. Hatzilau13

14. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS Disturbances of similar type with spikes & transientsare Voltage dips and swells* Voltage dips are events that present a temporary decrease in the rms voltage, in one or more phases. They are caused by an increase in current somewhere in the system e.g., during faults, motor starting and transformer energization [26]. * A voltage swell is a temporary increase in rms voltage. Swells are usually caused by fault conditions and do not exceed 1.7 p.u. in magnitude. A swell appears in the healthy phases during a single line-to-ground fault in ungrounded or impedance grounded systems. Presented by I.K. Hatzilau14

15. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS Adverse consequences of spikes & transients- Possible damages to insulation. - Misfiring of Semiconductor switchesby the rate of voltage change, leading to device failures or even errors in data processing devices. - False tripping of adjustable speed drives. - Regarding surge protective devices transients in voltage as well as in current are crucial. Failures have been identified, that are linked to current and not to energy. … etc. … Presented by I.K. Hatzilau15

16. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS Voltage ( and Current ) Transients are characterizedconsidering the actual values of the waveform. Values that are used for characterization purposes are :- The peak value - rise time - energy - time to crest- time to half the crest- frequency and energy - repetition rate … etc …* Source and surge impedance, system’s configuration and components, effect significantlythe characteristics of voltage and current transients. Presented by I.K. Hatzilau16

17. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS *Researchers have shown,that characterization of transients cannot be limited to a single value like energy in voltage[20], [21]. Several characteristics must be considered,because different types of loads appear to be sensitive to different transient characteristics.*The importance of the current during the transient has been also shown [19]. Presented by I.K. Hatzilau17

18. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS For example :*Thyristors are effected by the maximum rate of rise, the peak amplitude and I2t *Data processing equipment is also effected by the repetition rate* In the Varistors, surges of the same energy but different characteristics, result to different energy depositionThis means, that the concept of “specific energy”(  V2/R dt with R=50 ohms )is not appropriatefor selecting the energy-handling rating ofa varistor Presented by I.K. Hatzilau18

19. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS This table shows consequences of the characteristic parameters of a surge, according to Dr. MARTZLOFF et. al. [ Ref. 19 -22 ]. Presented by I.K. Hatzilau19

20. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 2. CHARACTERIZATION PARAMETERS Adverse consequences of dips & swells* Malfunctionof computer-like equipment(electronic equipment and process control equipment)( reset, incorrect operation or shutdown ).* For adjustable speed drives, the reduction in speed or torque might not be tolerated, by the process driven by the drive. * Problems to motor-drive controllers. * Induction motors might not also manage to reaccelerate after the reduction in speed, that is caused by the voltage dip [3]. * Mis-operation ofContactors. * andLike transients, swells can be harmful for electrical insulation. Presented by I.K. Hatzilau20

21. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards In contrast to the All Electric Ship (AES) perspective domination, no significant results (even for more conventional type ships) from investigating and classifying these phenomenahave been recently reported following up ..- the extensive electrification,- and the technological progress in the field of sophisticated power subsystems installed onboard, as well as in the domain of Surge Protective Devices (SPD) and measurement equipment. * On the contrary, most ship-standardshave been based on measurements and analyses performed almost twenty to thirty years ago ….. ! ! ! Presented by I.K. Hatzilau21

22. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.1 General overview of standardsIn the following slides we present :the results of thecomparisonof Permissible Limits and Test Proceduresset by Classification Society rules, norms, standardsetc, Presented by I.K. Hatzilau22

23. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.1 General overview of standardsTable II. A : Comparison of shipboard Standards regarding LIMITS of Voltage Transients and Spikes Presented by I.K. Hatzilau23

24. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.1 General overview of standardsTable II. B : Comparison of shipboard Standards regarding TESTS for Voltage Transients and Spikes Presented by I.K. Hatzilau24

25. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.1 General overview of standardsThe main remarks are :- no (commercial) Classification Societyknows“spike” phenomenon, while most of them,do not prescribeany test procedure for spikes and transients- only IEEE-45 andSTANAG 1008 know “spike” phenomenon .. !! Presented by I.K. Hatzilau25

26. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2. Military Standards( STANAG 1008, USA-MIL-Std-1399)The specifications of the electrical power plants in NATO naval vesselsare laid down in STANAG-1008, which is a document, that has come out of USA MIL-STD-1399(NAVY)–Section 300A ,under the responsibilityof the SubGroup/4 of the NG/6 of NATO AC/141. The terminology and the “philosophy” of STANAG 1008 is not always consistent with the standards,that are widelyused in continental systems ( e.g. with IEEE ) Presented by I.K. Hatzilau26

27. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards Definitions and Limits of Spikes and Transient in STANAG 1008According to USA MIL-STD-1399(NAVY)–Section 300A and to Editions 7, 8 and 9 of STANAG 1008, which hold for about seventeen yearsthe definitions and the limits for voltage Transient and Spikes can be summarized as follows : Presented by I.K. Hatzilau27

28. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards Voltage Transient is a sudden change in voltage (Ed.9: .. in the peak amplitude of the voltage),which exceeds the user voltage tolerance limits for a time longer than 1 msec and less than 2 sec (Ed.9: .. the typical time duration is between a fraction of a cycle and 2 sec).Limits : AC systems: +/-16% (under circumstances +/-22%). In 24V DC systems: 18-35V.Voltage Spike is a voltage transient of short duration (less than 1 msec) (Ed.9: A voltage spike is usually less thana quarter cycle in duration).Limits : In AC systems: 2.5kV (in 440V supply) or 1kV (in 115V supply). In 24V DC systems: 600V. Presented by I.K. Hatzilau28

29. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards In this Figure we see graficalythe Definitions and Limits of Spikes and Transientin STANAG 1008, Ed.8(& ..Ed.9) (AC systems) Fig.1:(a) acceptable spike, (b) acceptable transients, (c) unacceptable spike, (d) unacceptable transient. t(1,2) and t(5,6) < 1msec. t(3,4) and t(7,8) > 1msec. Presented by I.K. Hatzilau29

30. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards So, we see the inconsistencyof STANAG 1008with IEEE 1159 :- In STANAG 1008 the term “spike” is used to describe what in IEEE 1159 is described as “impulsive transient”, and the term “transient” is used to describe anything that is longer than 1 msec (or longer than “a fraction of a cycle” in Ed. 9).Other sources of skepticismregarding STANAG 1008, are described next. Presented by I.K. Hatzilau30

31. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.aSpike peak limitsThe spikes limits[2.5kV for 440V supply & 1kV for 115V supply]in USA MIL-STD-1399(NAVY)–Section 300A and in STANAG 1008have been based on measurements performed almosttwenty to thirty years ago, while no actual amendments on this topic have been made. These limits are also adopted in IEEE Std 45-Ed.1998.- These limits have been the outcomes mainly of the measurements of two projects in year 1972[27] and in years 1978-1981[28]on U.S. Navy vessels. Presented by I.K. Hatzilau31

32. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.a Spike peak limits This diagram is the famous HISTOGRAM of Mr S.F. CANNOVA From this diagram the 2.5 kV Spike-limit is derived, following Measurements on U.S. Navy vessels dated from 1972 !! Presented by I.K. Hatzilau32

33. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.a Spike peak limits - These spikes limits are often criticised, however in the absence of more recent surveys there has been no changes. - Additionally, the extended use of surge protection devices has led several researchers to conclude – erroneous– that the issue of spikes,is not as important as it used to be. * - This issue has been risen already in continental systems and it has been demonstratedthatwithout appropriate measurements the results can be misleading[17], [22].What is the problem ? Presented by I.K. Hatzilau33

34. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards Spike peak limits & point of measurements The measurement downstream a surge arrester does not give any hint of the actual spike chopped. The problem is magnified considering the ship grid in its entity … like in the next figure .. Presented by I.K. Hatzilau34

35. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards Spike peak limits & point of measurements Presented by I.K. Hatzilau35

36. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.b Spike waveshape, Test-impulse, Test-methode * Measurements and theoretical analysis show, that most voltage spikes in small-size Low-Voltage systems (as ship systems are) have oscillatory waveshapes, unlike the unidirectional waves, usually specified in high-voltage insulation standards ([5], [18], [23], [24]). - In STANAG 1008 only the unidirectional "Lightning-Impulse"-IEC 60060-1 (Figure 2 up) is recommended for test purposes. - However, other standards include also the "Ring Wave"-0.5μsec-100kHz (Figure 2 down, from IEEE “Surge-Trilogy” [5]). Presented by I.K. Hatzilau36

37. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.b Spike waveshape, Test-impulse, Test-methode Fig. 2 : Test waveshapes, (left) : STANAG 1008 "Lightning-Impulse" IEC 60060-1, (right) : "Ring Wave" - 0.5μsec - 100kHz[IEEE “Surge-Trilogy”]. Presented by I.K. Hatzilau37

38. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards • 3.2.c Voltage / Spike Transient Envelope • The Limits of voltage Spikes & Transients are represented by a curve • in a amplitude(DV)-duration(Dt) diagram, • separating the permissible and not-permissible areas. • Several standards , like • - ITIC [8], • - DIN VDE 0160 A1 [9], • - USA MIL-STD-704E [11] • … etc … • use an intermediate “sloped” section of the curve • in the amplitude-duration diagram, • even if there are some variations between the standards. • …. For example …. Presented by I.K. Hatzilau38

39. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.c Voltage / Spike Transient Envelope DIN VDE 0160 A1 DIN VDE 0160 A1, "Electronic equipment for use in electrical power installations and their essembly into electrical power installations" Presented by I.K. Hatzilau39

40. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.c Voltage / Spike Transient Envelope USA MIL-STD-704E USA MIL-STD-704E, “Aircraft Electric Power Characteristics”, 1 Nay 1991 Presented by I.K. Hatzilau40

41. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.c Voltage / Spike Transient Envelope .. but … STANAG 1008 Ed.8 distinguishes abruptly – and in contradiction to the real natural phenomena - between “spike” and “transient” in the amplitude(DV)-duration(Dt) diagram. e.g. in a 440V system : it permits a voltage disturbance of 2000 V, if it has a duration of 990 μsec - because it is a “spike” – but if the duration is a little longer, e.g. 1010 μsec, the permitted value is much smaller, only about 760 V(= 1.22x2x440 V) - because it is a “transient” … !!!. Presented by I.K. Hatzilau41

42. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards • 3.2.c Voltage / Spike Transient Envelope • Additionally, in Ed.9 of STANAG 1008, • the criterionfor distinguishing transients from spikes • is not clear and this lead to confusion • Namely, the duration-limitof a spike • overlapswiththe transient-duration-limit… !!! • So, for example, a disturbance of 3 msec duration • and peak magnitude of 900 V, falls into both categories … !!! • It will be acceptable, if we call it “spike” • but not acceptable if we say, it is a “transient” … !!! Presented by I.K. Hatzilau42

43. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards Comparison between ITICcurve and STANAG 1008 (dashed line) Shadowed area :Ed. 9 In ITIC curve two different areas are defined, (for oscillatory and for impulsive transients) having different slopes. (applicable to 120 V – 60 Hz equipment ) Presented by I.K. Hatzilau43

44. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras ITIC STANAG 1008 Spike-Transient Envelope: STANAG vs ITIC STANAG 1008 Ed.8 distinguishes abruptly (example for a 440 V system) duration = 990 μsec then it is a Spike Max voltage = 2000 V duration = 1010 μsec then it is a Transient Max voltage = 760 V.. !!! Presented by I.K. Hatzilau44

45. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras ITIC STANAG 1008 Spike-Transient Envelope: STANAG vs ITIC “Confusion” from the Shadowed area in STANAG Ed. 9 (example for a 440 V system) Surge duration = 3 msec Surge amplitude = 900 V as a Spike acceptable but as a Transientunacceptable 3 msec Presented by I.K. Hatzilau45

46. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.d Voltage and current spikes The voltage spike test that STANAG 1008 proposes, the “lightning impulse”, has characteristics that are based on the concept of energy(100 joules on 2 ohm load). But it has been shown ([19], [20], [21]),that this is a misleading oversimplification. * e.g. the energy, that a metal-oxide varistor must handle,dependsalso on amplitude, waveform, source impedance and varistor characteristics and NOT only on the energy calculated by the voltage waveform. Additionally there are cases, where the failure mechanism is totally independent from energy. Current surges have also a critical effect on the failure mode and they are also system depended. Presented by I.K. Hatzilau46

47. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards • 3.2.e Severity assessment of short duration variations • [dips and swells] • For events of duration of several cycles • STANAG 1008 uses the voltage peak, as a measure of the disturbance severity, while IEEE and IEC uses rms values(the way that rms is calculated is described in detail: window, interval, etc). • Although peak value is appropriate for impulsive and oscillatory disturbances, rms is the most appropriate way of describing events, like voltage dips and swells. • Peak voltage is not always representative of the actual event, especially in the presence of harmonics. Presented by I.K. Hatzilau47

48. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards This Figure shows the measurement of a of a voltage waveform and of the rms voltage during transformer energizing. (up): Voltage waveform (down): rms voltage and positive peak voltage (thicker) line the difference between the two is significant there is an asymmetry between the negative and positive peak voltages due to the unsymmetrical nature of the transformer inrush current. Presented by I.K. Hatzilau48

49. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards 3.2.f Supply Interruptions Although USA MIL-STD-1399(NAVY)–Section 300A (a source document for STANAG 1008) considers supplyinterruptions as a power quality parameter, STANAG 1008 does NOT, due to the fact, that STANAG 1008 refers essentially to ahealthy electrical power supply system. Nevertheless, Power Supply Interruptions are an important aspect of power quality and it must be included in a monitoring survey, with all the relevant details (cause and duration), in order to evaluate the performance of the electrical system, identify the weak components, apply enforcements and select appropriate power quality mitigation equipment. Presented by I.K. Hatzilau49

50. Voltage and Current Spikes & Transients - Power Supply Quality aspects for the AES I.K. Hatzilau, J. Prousalidis, E. Styvaktakis, E. Sofras 3. Comparative analysis and evaluation of Shipboard Standards • 3.3. Particular aspects of AES • Almost all AES-evolution trends would be inherently correlated to several adverse PSQ phenomena. • More specifically : • Motor drive converters would provoke, besides harmonic problems, also not easily predictable switching transients, mainly due to problems • during commutation of power electronic switches. • * Pulsed loads, are, by default, a major voltage dip source. Presented by I.K. Hatzilau50