the off-line diagnosis of circuit breakers with the time domain and
Contents
1. c 1 F 2 3 Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 an useful relationship for determining the time f elapsed since the voltage application on the coil and the start of the journey for mobile armature L U t In R U R F c 4 Massive iron core electromagnets have a time t to start a few times higher than those determined by the relationship above because the phenomenon of electromagnetic field penetration For a small starting time the magnetic material for the electromagnet should be made of sheets In an electromagnet with the initial air gap oo the value of its proper inductance by neglecting the iron reluctance and dispersion field 1s _N A Oy 5 L t If the armature has moved with v dat the 0 inductance becomes E N A Lh _ N A Lh 1 6 L t 5 fv dr 0 relationship in which Z it is the moving armature displacement made during the time at constant speed v and the variation of inductance L is written 7 T SA 7 t t a Jude 0 case in which the relationship 1 becomes 7 8 ta E M i The equation 8 solution shows the current variation depending on time with the moving speed as parameter which is a function depending of the current of the coil Therefore solving equation 8 is a very difficult task but it is noteworthy that a high value of rate of change of inductance dL2. measurements of vibration ISO 8041 2005 Each of the four available channels three for vibration and one for sound can run simultaneously with independent input configuration transducer type filters and RMS detector of time constants The four channels allow parallel measurements by independently defined filters and RMS additional time detectors LEQ LMax LMin LPeak SPL SEL when measuring sound or RMS PEAK PEAK PEAK P P VDV MTVV in case of vibration measurements USB Memory Stick allows you to store a large number of information and measurement results can be easily downloaded to your PC using standard USB port optional RS 232 or IrDA The processing software is SvanPC and the analyzer SVAN958 has the following possibilities of operation e real time measurements measurements in 1 1 octave or 1 3 octave analysis including statistical computation e FFT analysis including overlapping spectra e measurement of the reverberation time noise dosimeter and rotational speed measurement The above features make this type of analyzer helpful in off line diagnosis in time and frequency domain analyzing three phase switching equipments Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 The authors conducted experimental determination of the contacts vibration in a circuit breaker IUP M I 630A U 12kV Year 1978 available in the electrical equipment
3. use practically Therefore the manufacturers of diagnosis and testing equipments for circuit breakers offer practical solutions to determine the speed of closing opening contacts and of the action time At At At At 3 CONDITIONS FOR THE SWITCHING EQUIPMENT TESTING The tests performed in ELECTRICA and TRANSELECTRICA installations and electrical equipments are made according to the norms 3 These norms are applied to the tests and check outs of equipments and electrical installations at the commissioning moment and in operation Measuring the action time and the non simultaneity of closing and contacts separation of different phases or contacts in series of the same phase is performed with electronic second meter e g type MINUT or using oscilloscopes The measured value must not exceed the reference value by more than 10 and the maximum non simultaneity between phases should not exceed Sms between opening and closing for circuit breakers used Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 for generators and transformers and 10ms in closing and Sms in opening for line switches The moment for the tests are CT the commissioning time RR the routine repair TR the technical revision and AI accidental intervention The non simultaneity moments are approximately 3ms for medium voltage and 5ms for high voltage The functional verification of circuit
4. Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 THE OFF LINE DIAGNOSIS OF CIRCUIT BREAKERS WITH THE TIME DOMAIN AND FREQUENCY VIBRATION ANALYSIS Horia BALAN Aurel BOTEZAN Mircea BUZDUGAN Elena STEFAN Gabriel PIRV Petros KARAISSAS Technical University of Cluj Napoca e mail horia balan eps utcluj ro T EI of Piraeus Greece email pkara ktpae gr Abstract This paper presents a methodology for determining the operation time at opening and closing of the circuit breakers using multi channel sound and vibration analyzers All the tests on the circuit breaker are made according the prescriptions of normative 3 It is noteworthy that all tests prescribed by normative 3 are based on preventive diagnosis This paper approaches the issue of predictive diagnosis of circuit breakers by proposing an original method of comparing the witness pattern to actual pattern by the Dynamic Time Warping algorithm DTW This algorithm is developed by the Megger Company from Sweden and use FFT frequency analysis and time domain analysis To determine the speed and time of closing opening for circuit breakers the authors used sound and vibration analyzer Svan 958 which has tri axial accelerometers for vibration measurements and offers the opportunity to make independent measurements on three phase Using the multi channel analyzer in diagnosis of circuit breakers have the foll
5. User title e ee ae a ae ra a a se aie Ge Giese ae ak cia ae ec n tok am Se ag Se ae ks aaa a Ge a 4 000 4 1 4 al ace haa a a et ll a at Te la 2 000 7 SEEI EL 4 d j F i Tail A a Gr Tl a a E alee cabana a 13 52 38 000 13 52 38 960 13 52 39 920 13 52 40 880 13 52 41 840 Time 13 52 38 010 Cursor Time Date Function Main cursor Main cursor 13 52 38 010 04 Jun 10 RMS Ch3 P1 12 882 m s 2 Figure 5 Determination of closing time phase L3 Logger 1 3 Octave Channel 1 RMS Acceleration Filter HP 07 Jun 10 14 24 52 010 User title p p Cursor Frequency He Function Mancwsor In blocks Outside blocks Caleulated function Man cursor Total resu Wino 500 Ls m Figure 6 Simultaneous analysis in frequency domain phase L1 1 3 Octave Time intersection Channel 1 Acceleration Filter HP f 20 0H2 User ttle m gt LASLA 14 2453 200 142454000 142454800 14 2455 600 142456400 14 24 57 200 1424 58 000 4 2458 800 LAASI 425 000 14125101200 Tine Cursor Tne Date Function Meineursor blocks Outside bods Calculated function Mancuso Tetalresuk enor MSD td FUs we Figure 7 Simultaneous analysis in time phase L1 The highlighting of the damping system problems and a kinematics comparison between phases can be performed by determining the speed time c
6. ated function Main cursor Total result enor 131536540 mi FUs Bans Figure 10 The vibration speed opening closing opening cycle L3 phase 118 6 CONCLUSIONS The use of the multi channel analyzer in circuit breakers diagnosis presents the following advantages e enables the determination of the opening and closing times e by comparing the amplitude time characteristics the non simultaneity between the phases L1 L2 and L3 can be determined e the setting possibilities of the SVAN 958 analyzer in determining the acceleration velocity or displacement allows a diversity of possibilities for the dynamic behavior analysis e the frequency analysis by selecting 1 1 octave or 1 3 octave allows the analysis simplification by the method of Dynamic Time Warping in the predictive diagnosis procedures of circuit breakers 1 Ionescu I Racovitan I Using Modern Methods of Diagnosis Off line Medium and High Voltage Circuit Breakers in the Context of Transition to Maintenance Based on Reliability FOREN 2008 Neptune 15 to 19 June 2008 2 Hortopan G Electrical Apparatus Theory Design Testing EDP Bucharest 1978 3 PE 116 94 Norm for Testing and Measurement in the electrical installations and equipments 4 Programma Vibration Testing of High Voltage Circuit Breakers 5 Leonard F Landry C Beauchemin R Turcotte O Brikci F An Improved Algorithm Vibration Analysis as a Diagnos
7. breakers to closing and opening are done by five driving at rated voltage and rated pressure 5 driving at minimum voltage and or minimum pressure and five driving at maximum voltage and or maximum pressure We must obtain a safe operation without incidents and without any adjustments during the tests performed at the following moments CT TR and after AI Measurements of the movement speed of the movable contacts of the total stroke and contact stroke are made using a running drum and the measured values must fall within the limits set by the manufacturer The test moments are CT TR and after AI and the measurement become compulsory Checking kinematic characteristics for circuit breakers consists in the verification of opening and closing times as well as non simultaneities and to the separators in checking out the opening and closing times The tests were performed using the MINUT second meter and an oscilloscope the test moments are CT and TR Parameters must meet the values of product STR Domain Technical Standard The measurement of non simultaneity of the different phases contacts phases is achieved respecting the following prescriptions e The input terminals are linked in parallel and the output terminals are linked in the same mode The circuit breaker is interpolated in a series circuit with a bulb and a battery or a rectified source voltage to 12VDC e The circuit breaker is closed manually to achiev
8. dt determines a low value of current through the electromagnet coil The duration of action of the electromagnet means that the time between the moment of switching on of power supply circuit of the coil and the moment when the moving armature reaches the fixed armature To determine the action time on the magnetization curve f i we shall consider n intermediate points between the initial gap and final for which the magnetization curves are traced Between two successive points can be defined an average 114 velocity v constant If we neglect frictions the work which determines the variation of the kinetic energy 1S 9 FFA A E As we have stated before for the moving armature displacement from the gap value 6 to the gap value we may admit a constant average velocity Vm v 2 Equation 9 becomes 2 F E 5 8 10 and the velocity v is ME ase CC 11 m The displacement time from the air gap 0 to can be written 12 Considering a similar approach for other intervals the total driving time At 1s determined 13 Reducing the action time of the circuit breakers is achieved using iron laminations as magnetic circuits for the mobile armature a low weight and a low time constant for the moving armature From the applicative point of view the above relationships intended to determine the closing speed and the action time offer complicated solutions difficult to
9. e the contact on the first phase when the ignition lamp and in this position the distance between the contacts of other phases is measured with a feller gauge The maximum value of the non simultaneity of the contacts must be Imm the test is performed in the following situations R RR TR and AI 4 THE PROBLEM OF PREDICTIVE MAINTENANCE It is noteworthy that all tests prescribed by norm PE 116 are based on prophylactic diagnosis Excepting the commissioning moment CT and the accidental intervention AI in the case of technical review TR and routine repairs RR is noticeable that the current trend offered by this type of diagnosis 115 to abandon the planned maintenance in the regulations prescribed intervals and adopting a predictive maintenance has a lot of technical and economic advantages From this point of view it can be mentioned the conduit of the Swedish company now MEGGER embedded in the equipments TM1600 MA61 and TM1800 Breaker Analyzer System with dedicated software CabaWin 4 The Company PROGRAMA uses a method of analysis named Dynamic Time Warping DTW DTW is based on checking similarities between two signals one witness mark at the commissioning moment of the breaker and a mark time when appropriate diagnosis are made Comparison between signals is based on FFT frequency analysis and time domain analysis Frequency and amplitude of the signal moment pattern are analyzed at every m
10. e MxQxL points where M is the vocabulary size Q is the average number of references word and L is the average length of words 116 Generally the actual number of points assessed is much smaller for two reasons e In the field 1 1 x 1 J only the area around the diagonal is relevant which reduces the area of interest by a factor of 0 4 0 1 e A word recognition compared to a reference may be neglected if the distance index D T R can not be below a given threshold or if the partial distance index normalized cumulative distance is significantly different from the lowest index of partial contrast for all references Under these conditions the number of actual treated points for a word is AMQL where a lt 1 and generalizing for the case of chained words without syntactic constraints we obtain N aMQKL2 where N is the number of points assessed for recognizing a sequence of words and K is the average number of words in a sequence 5 EXPERIMENTAL RESULTS To determine the speed and the moments of breaker s contacts closing opening the authors have used a sound and vibration analyzer SVAN 958 which uses tri axial accelerometers for vibration measurements which offers the opportunity to perform independent measurements on the three phases with three mono axial accelerometers SVAN 958 it is a digital analyzer 6 for channels in the frequency range 0 5 Hz 20 kHz including sound measurements IEC 61672 1 2002 and
11. ement depending on time The Electric Equipments Laboratory from Technical University of Cluj Napoca in order to offer services and researches for solving the off line diagnosis problem of circuit breakers targeted to purchase the following equipment e Equipment PME 100 for measuring contact resistance producer EUROSMC Spain e Equipment PME 500 for measuring the simultaneity of contact closing of the circuit breakers producer EUROSMC Spain e Sound and vibration Analyzer Svan 958 to determine the speed and driving time producer SVANTEK Poland 2 THEORETICAL CONSIDERATIONS Literature 2 provides graphic analytical solutions for determining the operating time and current variation in time during the closing or opening of the circuit breaker contacts For example for the circuit breakers the drive device is equipped with DC electromagnet in which case for the electromagnet mobile armature displacement calculation is necessary to take into account the variation of inductance with respect to time 1 d U R i1 R si dt For fixed armature dL dt 0 and for moving armature dL dt has a finite value While moving armature is driving appear eddy currents and hysteresis phenomenon but if we make abstraction of these phenomena the current through the coil at zero speed dL dt 0 is R ifi E R Moving armature starts to move when the active force F is equal to the opposite force F ede o Fo
12. h ee 1 1 1 1 1 iba idih do eer delet L 2 a a 1 i j t f I f i i i f i t t t i i foi bo a j i i i T 1 1 T 7 T T a es re ee ee S ee ee ee a L L 7 L L a I ad badd 1 l 1 1 1 1 MLELE ELULE CULLLETETLIL 1 l 1 1 1 I l 1 1 tomo e E A E E brag PPeid ad 4 Figure 2 Example of circuit breaker pattern containing errors Considering the plane splited into two areas A and B the time alignment function indicates the correlation between the time axes of the A and B sequences and can be represented by a sequence of points in the plane c i 7 15 If the spectral distance between the two characteristic vectors a and of the b is represented by d c d i j 16 then the sum of distances to the end of the sequence along of F is represented by gt d e wW D F F c C C Sessie Cis e i 17 The smaller value gives the better match similarity between A and B The computation volume of the comparison of the two acoustic oscillographs can be estimated by assessing the number of points ij treated by a dynamic programming algorithm in each point the algorithm have to calculate the local distance d i j and an partial aggregate cumulated g 1 J To compare two isolated words of length I and J all i j points of the grid 1 I x J are treated the process of isolated word recognition requires to examin
13. haracteristic during a complete cycle opening closing opening OCO on the three phases of the circuit breaker figure 8 9 and 10 Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 Logger results Channel 3 P1 Vel3 100 ms User title ti pt 4 __ _ 4 ASAA 13116135200 13115136000 131153600 13 15 37 000 13 15 38400 13115139200 13 15 40 000 13116140800 13 15 41 600 ISALA 1311543200 13115144000 Time Cursor Tine Date Function Main cursor Inblocks Outside blocks Calculated function Main cursor Total result Manuso 131536360 O5Juni0 Ulsen ta t62ms Figure 8 The vibration speed opening closing opening cycle phase L1 Logger results Channel 2 P1 Vel3 100 ms User title th tt i 131534400 1311536200 13 25 36 000 13 15 36 000 1311637600 131153800 1311639200 13 15 40 000 13116140800 13118141600 13 15 42 400 13115143200 13115144000 Time Cursor Time Date Function Main cursor Inblocks Outside blocks Calculated function Main cursor Total result minoor 1315330 O10 Lpvs et gans Figure 9 The vibration speed opening closing opening cycle phase L2 Logger results Channel 1 P1 Vel3 100 ms User title 13 45 34400 1311536200 13 25 36 000 131153600 1311537600 13 15 38400 1311539200 13 15 40 000 13 15 40 800 13A 13 15 42 4 1311543200 13 15 44 000 Time Cursor Time Date Function Main cursor Inblocks Outside blacks Calcul
14. illisecond 5 and the results are compared with the reference signal witness pattern DTW analysis requires a high bandwidth and high dynamic range DEVIATO 4 00 caidh r Q0 100 20 0 300 40 0 50 0 60 0 70 0 20 0 90 0 100 0 140 0 420 0 130 0 140 0 150 0 160 0 ms Figure 1 Example of circuit breaker pattern in which no changes appear The errors in a circuit breaker go first to deviations in time of the pattern from witness mark These deviations are illustrated in Figure 2 where one can see the difference between witness vibration pattern and moment vibration pattern of 10ms The DTW analysis determines the amplitude deviation between witness mark and time mark DTW compresses or expands the nonlinear time axis to synchronize the same phenomena oscillo graphs the test and reference model This process can be performed using dynamic programming technique which was first applied to the DTW algorithm for dynamic temporal alignment of words It involves two time sequences with the parameters represented by vectors Annals of the University of Craiova Electrical Engineering series No 34 2010 ISSN 1842 4805 A 4 45 500 5 B b b b gt a4 need to be compared Qi i T T F r T H 1 1 1 k bpd eT ore oe ce eter aT m mnd dahh wd 1 1 fl T T r r i a fj i dak ddi jalad d hni 1 i Ta i f neat ALLIT i H 1 1 1 innar 1 a a ee e
15. laboratory of the Technical University from Cluj Napoca Acceleration time diagrams velocity or displacement depending on the setting page Svan analyzer 958 of figures 3 4 and 5 allow to determine the mobile equipment acceleration the opening and closing times being useful in the design stage for checking the kinematics characteristics of the circuit breaker relations 4 11 and 13 Logger results User title m J s2 H H H H H H H H H H H H H H 300 000 000 200 000 150 000 100 000 50 000 r r 13 52 41 840 Time r r rs 13 52 40 830 r r r rs r r 13 52 38 000 13 52 38 960 13 52 39 920 13 52 38 010 Function RMS Ch1 P1 Main cursor 295 121 m s 2 Main cursor 13 52 38 010 04 Jun 10 Figure 3 Determination of closing time for the L1 phase As it is noted above the sound and vibration analyzer Svan 958 allows simultaneous analysis of the closing acceleration of the mobile armature in time and frequency domain as shown in figure 6 and 7 for the phase L1 Logger results User title m E i s2 H H H H H H H H H H H H H H 25 000 20 000 15 000 10 000 5 000 0 000 r 7 7 7 7 r r r r r 13 52 38 000 13 52 38 960 13 52 39 920 13 52 40 880 13 52 38 010 Cursor Time Date 13 52 38 010 04 Jun 10 ain cursor 27 861 m s 2 Function RMS Ch2 P1 Figure 4 Determination of closing time for the L2 phase 117 Logger results
16. owing advantages enable the opening and closing times determining by comparing the amplitude time characteristics can be determined the non simultaneity of phases L1 L2 and L3 the setting possibilities of the SVAN 958 analyzer to determine acceleration velocity or displacement allow dynamic behavior analyzing the frequency analysis by selecting 1 1 octave or 1 3 octave allows the analysis simplification by the method of Dynamic Time Warping in the predictive diagnosis procedures of circuit breakers Keywords dynamic time warping predictive diagnosis circuit breakers diagnosis 1 INTRODUCTION The continuity of power supply requires the electric energy transport operator Transelectrica and distribution operator Electrica to take measures for ensuring the electrical reliability of the national energy system equipments If we mean switching equipments we can say that the best solution is more reliable monitoring equipments but if we consider the price quality ratio we found that diagnosis is an acceptable solution Currently it tends to use predictive maintenance equipment in equipments Diagnosis instead of using preventive maintenance On national plan can be mentioned the ICEMENERG concerns 1 to off line 113 diagnosis by developing of DIACOM diagnosis set which performs on circuit breakers the contact resistance variation testing the current variation rate fluctuations in the drive coil and mobile contact displac
17. tic Tool for Detecting Mechanical Anomalies on Power Circuit Breakers IEEE Transaction on Power Delivery vol 23 no 4 October 2008 6 Svan 958 User Manual Svantek Poland
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