FRAX Series
Contents
1. PEWA Messtechnik GmbH Weidenweg 21 Megger 58259 Schwerte Tel 02304 96109 0 Fax 02304 961 09 88 E Mail info pewa de Homepage www pewa de X PEWA KeS Aiak MB electronic FRAX Series FRAX Series Sweep Frequency Response Analyzers Sweep Frequency Response Analyzers Description Power transformers are some of the most vital components in today s transmission and distribution infrastructure Transformer failures cost enormous amounts of money in unexpected outages and unscheduled maintenance It is important to avoid these failures and make testing and diagnostics reliable and efficient The FRAX series of Sweep Frequency Response Analyzers SFRA detects potential mechanical and electrical problems that other methods are unable to detect Major utilities and service companies have used the FRA method for more than a decade The measure ment is easy to perform and will capture a unique fingerprint of the transformer The measurement is compared to a reference fin gerprint and gives a direct answer if the mechanical parts of the transformer are unchanged or not Deviations indicate geometrical and or electrical changes within the transformer FRAX detects problems such as Winding deformations and displacements Shorted turns and open windings Loosened clamping structures Broken clamping structures m Core connection problems Partial winding collapse Faulty core gro2. 18 m cable set AC 19091 With accessories 9 m 30 ft cable set AC 19092 With accessories incl battery 9 m cable set AC 19093 FRAX 99 With accessories 9 m cable set AC 29090 With accessories 18 m cable set AC 29092 With accessories incl battery 9 m cable set AC 29095 Included accessories shown above Mains cable ground cable With accessories incl battery 18 m cable set AC 29096 2 ground braid sets 2 earth ground braid leads insulated FRAX 150 2 C clamps generator cable measure cable field test box With es 18 Bice AC 39090 nylon accessory pouch 2 earth ground braids with clamp See eee eee ee R A KE ee eae and canvas carrying bag for test leads With accessories 9 m cable set AC 39092 FTB101 Included accessories for all models Generator cable Measure cable 4x 3m 10 ft ground braid set 2x 0 3 m 1 ft braid with clamp 2 x C clamp bushing connector clamp 0 s 8 J a oi ab cn pox for FRAX 2 x G clamp ground clamp Field Test Box FTB101 Ground cable 5 m 15 ft Several international FRA guides recommends to verify the Mains cable integrity of cables and instrument before and after a test us ing a test circuit with a known FRA response supplied by the equipment manufacturer FRAX comes with a field test box User Manual FTB101 as a standard accessory and allows the user to perform Additional included accessories for FRAX 99 this important validation in the field at any time and
3. GERMANY Oberkulm FRAX series_DS_en_V01 T 46 8510 195 00 F 44 0 1304 207342 SWITZERLAND Johannesburg SOUTH www megger com F 468 510 195 95 AFRICA Kingdom of BAHRAIN Megger is a registered trademark E seinfo megger com Mumbai INDIA Chonburi THAILAND Sydney AUSTRALIA
4. and cost effective way to assess if damages have occurred or if the transformer can safely be energized again If there is a problem the test result provides valuable information that can be used as decision support when determining further action Having a reference measurement on a mission critical transformer when an incident has occurred is therefore a valuable investment as it will allow for an easier and more reliable analysis FRAX Series Sweep Frequency Response Analyzers Analysis and software As a general guideline shorted turns magnetization and other problems related to the core alter the shape of the curve in the lowest frequencies Medium frequencies represent axial or radial movements in the windings and high frequencies indicate problems involving the cables from the windings to bushings and tap chang ers 1M An example of low medium and high frequencies The FRAX Software provides numerous features to allow for ef ficient data analysis Unlimited tests can be open at the same time and the user has full control on which sweeps to compare The response can be viewed in traditional Magnitude vs Frequency and or Phase vs Frequency view The user can also choose to present the data in an Impedance or Admittance vs Frequency view for powerful analysis on certain transformer types m g EF 2 c a amp Z The figure above shows a single phase transformer after a service overhaul where by mista
5. be the same for every measurement on a given transformer Traditional ground connections techniques have issues when it comes to providing repeatable conditions This causes unwanted variations in the measured response for the highest frequencies that makes analysis difficult The FRAX braid drops down from the connection clamp next to the insulating discs to the ground connection at the base of the bush ing This creates near identical conditions every time you connect to a bushing whether it is tall or short and is the recommended way of connecting in CIGRE TB342 and IEC 60076 18 Hook up practice Main flat braid connected to coupling hanging next to bushing gt ef v m gt TI Short braid connected between main braid and bushing flange ND ei Lh NI AAA ze a a LES Solid connections using the C clamps and the shortest braid method to connect the shield to ground makes it possible to eliminate connection problems and cable loops that otherwise affect the measurement FRAX Series Sweep Frequency Response Analyzers FRAX 150 with Built in PC FRAX 150 has a built in PC with a high contrast powerful backlit screen suitable for work in direct sunlight The cursor is controlled via the built in joystick or using an external USB mouse and the built in keyboard makes data entry easy All data is stored on the built in hard drive The data can be moved to any other compute
6. secure AC DC adapter measurement quality Light t t ight transport case FRAX software for Windows Canvas carrying bag for accessories Optional accessories USB cable FDB101 Additional included accessories for FRAX 101 AC DC adapter Transport case Bluetooth adapter USB cable Additional included accessories for FRAX 150 Canvas carrying bag for accessories Optional Accessories The FRAX Demo box FDB101 is a transformer kit that can be Calibration set FRAX Demo Box FDB 101 FRAX Generator and Ref cable 9 m 30 ft FRAX Generator and Ref cable 18 m 60 ft FRAX Measure cable 9 m 30 ft AC 90020 AC 90050 GC30040 GC30042 GC 30050 used for in house training and demonstrations The small transformer is a single phase unit with capability to simulate FRAX Measure cable 18 m 60 ft GC 30052 normal as well as fault conditions Open as well as shorted Cclamps GC 80010 measurements can be performed The unit also contains two I test impedances one of them the same as used in the FTB101 E clamp single hand grip clamp GC 80030 field test box SWEDEN UK Other Technical Sales Offices Registered to ISO 9001 and 14001 Megger Sweden AB Archcliffe Road Dover Dallas USA Norristown USA Subject to change without notice Eldarvagen 4 Box 2970 CT17 9EN England Toronto CANADA Trappes FRANCE Art No ZI ACO5E Doc ACxxxxAE e 2012 SE 187 29 TABY T 44 0 1304 502101 Oberursel
7. consequently affect capacitances and change the shape of the curve The SFRA method is based on com parisons between measured curves where variations are detected One SFRA test consists of multiple sweeps and reveals if the trans former s mechanical or electrical integrity has been jeopardized L O D OQ IL S oO D C S H Practical application In its standard application a finger print reference curve for each winding is captured when the transformer is new or when it is in a known good condition These curves can later be used as refer ence during maintenance tests or when there Is reason to suspect a problem The most reliable method is the time based comparison where curves are compared over time on measurements from the same transformer Another method utilizes type based comparisons between sister transformers with the same design Lastly a con struction based comparison can under certain conditions be used when comparing measurements between windings in the same transformer These comparative tests can be performed 1 before and after transportation 2 after severe through faults 3 before and after overhaul and 4 as diagnostic test if you suspect potential problems One SFRA test can detect winding problems that requires multiple tests with different kinds of test equipment or problems that cannot be detected with other techniques at all The SFRA test presents a quick
8. emands on test equipment test leads and test set up FRAX is designed with these requirements in mind It is rugged able to filter induced interference and has the highest dynamic range and accuracy in the industry FRAX dynamic range or noise floor is shown in red below with a normal transformer mea surement in black A wide dynamic range low noise floor allows for accurate measurements in every transformer A margin of about 20 dB from the lowest response to the instruments noise floor must be maintained to obtain 1 dB accuracy Minimum 20dB M i la i i FWA Vy ney i f piera 0 fr teeee OD pii An example of a transformer measurement in comparison with the internal noise level in FRAX Megger Close up of FRAX 150 control panel Test button Built in mouse with left and right click buttons sealed to protect from dust and other contaminants Navigation arrows Enter key Specifications FRAX 99 101 150 Specifications are valid at nominal input voltage and an ambient temperature of 25 C 77 F Specifications are subject to change without notice Environmental Application field The instrument is intended for use in medium and high voltage substations and industrial environments Ambient temperature Operating FRAX 150 5 C to 50 C 23 F to 122 F FRAX 99 101 20 C to 55 C 4 F to 131 F Storage 20 C to 70 C 4 F to 158 F Humidity lt 95 RH non condensing CE ma
9. ic scale or combination of both 20 to 115 dB FRAX99 20 to 130 dB FRAX101 and 150 0 3 dB from 10 dB down to 40 dB 0 5 dB down to 100 dB FRAX 101 150 1 dB down to 100 dB FRAX 99 User selectable default lt 10 Internal USB galvanically isolated Bluetooth and USB galvanically isolated USB galvanically isolated FRAX for Windows 2000 XP Vista 7 Fulfill requirements in Cigr Brochure 342 2008 Mechanical condition assessment of transformer windings using FRA DL T 911 2004 FRA on winding deformation of power transformers IEC 60076 18 and IEEE PC57 149 as well as other standards and recommendations 1 0 20 24 V p p FRAX 101 150 20 V p p FRAX 99 0 1 12 V p p FRAX 101 150 10 V p p FRAX 99 500 Short circuit protected 0 1 Hz 25 MHz Low to high or high to low 2 Simultaneously 0 1 Hz 25 MHz 500 100 MS s Windows XP embedded 1000 records in internal memory External storage on USB stick PC Requirements FRAX 99 101 Note PC not included Operating system Processor Memory Hard drive Interface Windows XP Vista 7 Pentium 500 MHz or higher 256 Mb RAM or more Minimum 30 Mb free Wireless USB FRAX 99 101 USB and Ethernet FRAX 99 Megger FRAX Series Sweep Frequency Response Analyzers Included accessories Ordering information Item Art No FRAX 101 With accessories 18 m 60 ft cable set AC 19090 egger With accessories incl battery
10. ke the core ground never got connected red and after the core ground was properly connected green This potential problem clearly showed up at frequencies between 1 kHz and 10 kHz and a noticeable change is also visible in the 10 kHz 200 kHz range Megger Features and benefits Built in decision support is provided by using a built in analysis tool based on the based on the SFRA standard DL T 911 2004 Smallest and most rugged FRA instrument in the industry Guaranteed repeatability by using superior cabling technology thus avoiding the introduction of error due to cable connection and positioning which is common in other FRA manufacturers equipment Fulfills all international standards for Sweep Frequency Response Analysis SFRA measurements IEC 60076 18 Method 1 Highest dynamic range and accuracy in the industry allowing even the most subtle electro mechanical changes within the transformer to be detected Advanced analysis and support software tools allows for sound decision making with regard to further diagnostics analysis and or transformer disposition Built in PC with powerful backlit screen for use in direct sunlight FRAX 150 FRAX Series Sweep Frequency Response Analyzers Test Object Browser Unlimited number of tests and sweeps Full user control Quick Select Tabs Quickly change presentation view for differ ent perspectives and analysis tools Quick Graph Buttons Program
11. mable graph setting lets you change views quickly and easily Sweep Curve Settings Every sweep can be individually turned on or off change color thickness and position Dynamic Zoom Zoom in and move your focus to any part of the curve Operation Buttons All essential functions at your fingertips se lect with mouse function keys or touch screen Automated analysis compares two curves using an algorithm that compare amplitude as well as frequency shift and lets you know if the difference is severe obvious or light H2 H0 open i Eao open O Brom o Bexi oon g Exon O Emo open Bremon O x ee open x lt x1 x3 open e E E7 Bex oona Box open 1 Q Megger Considerations when performing SFRA measurements SFRA measurements are compared over time or between different test objects This accentuates the need to perform the test with the highest repeatability and eliminates the influence from external pa rameters such as cables connections and instrument performance FRAX offers all the necessary tools to ensure that the measured curve represents the internal condition of the transformer Good connections Bad connections can compromise the test results which is why FRAX offers a rugged test clamp that ensures good connection to the bushings and solid connections to the instrument Shortest braid concept The connection from the cable shield to ground has to
12. r using a USB memory stick Import and Export The FRAX software can import data files from other FRA instruments making it possible to compare data obtained using another FRA unit FRAX can import and export data according to the internation al XFRA standard format as well as standard CSV and TXT formats Optimized sweep setting The software offers the user an unmatched feature that allows for fast and efficient testing Traditional SFRA systems use a logarithmic spacing of measurement points This results in as many test points between 20 Hz and 200 Hz as between 200 kHz and 2 MHz and a relatively long measurement time The frequency response from the transformer contains a few reso nances in the low frequency range but a lot of resonances at higher frequencies FRAX allows the user to specify less measurement points at lower frequencies and high measurement point density at higher frequencies The result is a much faster sweep with greater detail where it is needed Variable voltage The applied test voltage may affect the response at lower frequen cies Some FRA instruments do not use the 10 V peak to peak used by major manufacturers and this may complicate comparisons between tests FRAX standard voltage is 10 V peak to peak but FRAX also allows the user to adjust the applied voltage to match the voltage used in a different test Dynamic range Making accurate measurements in a wide frequency range with high dynamics puts great d
13. rking EMC 2004 108 EC LVD 2006 95 EC General Mains voltage 90 264 V AC 47 63 Hz Dimensions Instrument FRAX 150 305 x 194 x 360 mm 12 x 7 6 x 14 2 FRAX 99 101 250 x 169 x 52 mm 9 84 x 6 65 x 2 05 Transport case FRAX 150 FRAX 99 101 520 x 460 x 220 mm 20 5 x 18 1 x 8 7 Weight Instrument FRAX 150 6 kg 13 Ibs FRAX 99 101 1 4 kg 3 1 Ibs 1 8 kg 4 Ibs with battery Case and accessories FRAX 150 16 kg 35 Ibs FRAX 101 15 kg 33 Ibs FRAX 99 12 kg 26 Ibs FRAX Series Sweep Frequency Response Analyzers Measurement section Test method Frequency range Frequency resolution Frequency inaccuracy Level resolution Number of points Measurement time Points spacing Sweep settings Dynamic range inter nal noise Inaccuracy IF bandwidth PC Communication FRAX 150 FRAX 101 FRAX 99 Software Standards guides Analog Output Channels Compliance voltage Measurement voltage at 500 Output impedance Protection Frequency range Sweep direction Analog Input Channels Sampling Frequency range Input impedance Sampling rate PC FRAX 150 Operating system Memory Sweep frequency SFRA 0 1 Hz 25 MHz user selectable lt 0 01 lt 0 01 lt 0 001 dB Default 1046 Up to 32 000 points user selectable Default 64 s fast setting 37 s 20 Hz 2 MHz Log linear or both Individual settings for customer defined frequency bands Linear and logarithm
14. unds Core movements Highest dynamic range and accuracy in the industry Smallest and most rugged FRA instrument in the industry Fulfills all international standards for SFRA measurements Advanced analysis and decision support built into the software Imports data from other FRA test sets A y amp CS c a Ld z Collecting fingerprint data using Frequency Response Analysis FRA is an easy way to detect electro mechanical problems in power transformers and an investment that will save time and money Megger Application Power transformers are specified to withstand mechanical forces from both transportation and in service events such as faults and lightning However mechanical forces may exceed specified limits during severe incidents or when the insulation s mechanical strength has weakened due to aging A relatively quick test where the fin gerprint response is compared to a post event response allows for a reliable decision on whether the transformer safely can be put back into service or if further diagnostics is required Method basics A transformer consists of multiple capacitances inductances and resistors a very complex circuit that generates a unique fingerprint or signature when test signals are injected at discrete frequencies and responses are plotted as a curve at Capacitance is affected by the distance between conductors Movements in the winding will
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