CM3156 EN DMx Internal Drivers App Note 011813.indd
Contents
1. 4 780 680 100 2 620 470 150 3 492 470 22 f 385 270 100 15 Component values Resistance K0 11 50 7 68 6 34 5 36 Table 5 CMSS 68 10 m 32 8 ft system Channel number Capacitance pF 1 430 330 100 2 270 3 150 4 66183 33 Resistance kQ 1000 00 15 00 9 09 6 81 aKF Appendix A SKF compensation modules and libraries An overview of currently available compensation modules follows Compensation modules SKF Multilog Part number SKF probe type System length DMx channel CMMA965 5 1 65 5 m 16 4 ft CH1 CMMA965 5 2 65 5 m 16 4 ft CH2 CMMA965 5 3 65 5 m 16 4 ft CH3 CMMA965 5 4 65 5 m 16 4 ft CH4 CMMA965 10 1 65 10 m 32 8 ft CH1 CMMA965 10 2 65 10 m 32 8 ft CH2 CMMA965 10 3 65 10 m 32 8 ft CH3 CMMA965 10 4 65 10 m 32 8 ft CH4 CMMA968 5 1 68 5 m 16 4 ft CH1 CMMA968 5 2 68 5 m 16 4 ft CH2 CMMA968 5 3 68 5 m 16 4 ft CH3 CMMA968 5 4 68 5 m 16 4 ft CH4 CMMA968 10 1 68 10 m 32 8 ft CH1 CMMA968 10 2 68 10 m 32 8 ft CH2 CMMA968 10 3 68 10 m 32 8 ft CH3 CMMA968 10 4 68 10 m 32 8 ft CH4 Note Listed libraries are generated using an AISI 4140 steel target Source DMx Sales Tool 2013 01 16 Protected xls Technical support For additional information on SKF products contact SKF USA Inc Condition Monitoring Center San Diego 5271 Viewridge Court San Diego California 92123 USA Telephone 1 858 496 3400 Fax 1 858 492. For use as a tacho source rather than measurement source a lineariza tion library and infinite gap calibration are not actually required but com pensation components should still be installed to optimize the ECP probe and extension cable to the SKF Multilog DMx hardware Software SKF Multilog DMx Manager and SKF Multilog DMx Toolbox are the two software packages that support the configuration aspects of the SKF Multilog DMx When working with an SKF Multilog DMx module always bear in mind that the configuration seen in software may not reflect the SKF Multilog DMx module unless an upload is actioned and that configu ration changes made in software will not be implemented in the module unless a download is made If using both packages be aware that changes made in one will generally mean that information in the other is now out of date and will need to be refreshed akF In addition any configuration changes even when downloaded may not be permanently stored onboard the SKF Multilog DMx module unless the appropriate procedure has been followed Refer to the relevant manual or help file for more detailed guidance Compensation modules For directly connected eddy current probes the internal SKF Multilog DMx driver circuit broadly matches to the attached probe and exten sion cable by use of compensation components While these could consist of a separate capacitor and resistor fitted to the base termi nals the fitting of i
3. Software can be Eo a e e e used to troubleshoot SKF Multilog DMx 4 Disabled 0 Wo J OZ O J J J J f Toolbox is the preferred tool In SKF Multilog DMx Toolbox ECP Tools contains the rele vant utilities As in the example below for channel 3 ensure that i Fig 10 DMx Activate ECP Lib dialog 1 The channel is configured for a direct ECP 1g 10 DMx Activate EGP Libriry dalog and the relevant library is loaded to the SKF Multilog DMx and linked activated to that channel ECP Tools tab Link Library to Channel fig 10 2 There is an infinite gap calibration with fe Lo Er aree channe erat Dianita EERE eee oe ECP Tools tab Calibration Management gt ARN inneonmna anne CAND TA v anne fig 11 fig Fig 11 DMx ECP Calibration Location Management dialog Note If not known the probe reference can be viewed in SKF Multilog DMx Manager Measurement Channel Properties on the Eddy Current tab 3 Confirm the probe oscillation frequency ECP Tools tab Get ECP Data fig 12 Note Read the display carefully paying particular attention to the scientific notation used to display the oscillation frequency Expected values are in the range 500 kHz to 1 200 kHz A value around 94 kHz or 94E 3 Hz is not normal and would indicate no oscillation 4 lf the expected probe and extension cable are in place any required compensation components are fitted yet multiple ECP channels appear not to
4. a compensation module and a default library are both available then the prerequisites are in place and all that remains is to bring the different elements together in the same place to perform an infinite gap calibration e Fit the probe and extension cable e Fit the compensation components e Power the SKF Multilog DMx and load the required library e Configure the SKF Multilog DMx channel and associate that library with it e Perform and store an infinite gap calibration e Confirm the performance of the system with a calibration curve e f required in the SKF Multilog DMx channel configuration replace the nominal sensitivity value by the actual verified sensitivity Note that the infinite gap calibration requires that the probe tip be in free air so it is usually more conveniently performed before fitting the probe to the machine DMx Module 1 DMx Module Type Compensation or Interface Module Reference Linearization Extension Cable Model Number Probe Type Channel Sensor MSS 958 xx D45 Model Number ACC DMX COMP MDL 68 5M CH1 CMSS 958 xx D45_ CMMA 968 5 2 ACC DMX COMP MDL 68 5M CH2 CMMA 68 05m 4140 090mil 9002 CMSS 958 xx D45 CMMA 968 5 3 ACC DMX COMP MDL 68 5M CH3 CMMA 68 05m 4140 090mil 9003 Library File CMMA 68 05m 4140 090mil 9001 Information ACC DMX COMP MDL 68 5M CH4 CMMA 68 05m 4140 090mil 9004 Fig 2 Screenshot from the SKF Multilog DMx Sales T
5. has driven much of the SKF Multilog DMx design An SKF Multilog DMx CMMA 9010 9910 module has four internal ECP drivers channels 1 to 4 while a CMMA 9020 9920 contains two channels 3 and 4 To customize an SKF Multilog DMx driver for a particular application normally requires all of the following three elements to be in place e Compensation module Matches the probe extension cable combination to the SKF Multilog DMx driver hardware and pro vides control of oscillation amplitudes and frequencies There will be a specific compensation module for each channel Compensa tion modules are designed to operate with special cut to nominal length extension cables see The SKF Multilog DMx Sales Tool sec tion later in this document gt page 4 e An ECP library Provides a number of coefficients that the SKF Multilog DMx can use to linearize the probe signal to be able to provide proper gap vibration data There will be a different library for each channel optimized for the hardware probe type tip coil size system length and compensation module measurement range and target material e An ECP infinite gap calibration A spot calibration that enables the SKF Multilog DMx to calculate from the associated library linearization coefficients that are optimized for the actual probe extension cable compensation module and SKF Multilog DMx hardware in use The sections that follow describe each of the above in more detail
6. range For a nominal 200 mV mil sensitivity system API670 allows 5 or an allowable range of 190 to 210 mV mil PostionError Fig 8 Minimizing DSL error example As the input sensitivity of each channel of the SKF Multilog DMx is individually configuration gt fig 9 the calibration curve tool can be used to provide optimum settings for the actual channel sensitivity Note that based on the recommendations from the report the user will have to manually reconfigure the SKF Multilog DMx module not ing the comments made in the Software section gt page 3 of this document about the need for downloading DMx measurement channel properties General Transducer Measurement Wavefomm FFT Orders Details AC units DC units TX OK low threshold mi a v a 18 0 aj y AC sensitivity m mil DC sensitivity mv Z TX OK high threshold 194 50 1000 00 aj 2 0 aj Y Fig 9 Configuring a specific sensitivity in SKF Multilog DMx Manager akF Maintenance and troubleshooting Routine maintenance Periodically check the security of the ECP connections e Check the tightness of the coaxial SMC connectors connecting the extension cable to the SKF Multilog DMx base and where applicable the in line connector between the probe cable and the extension cable e Ensure any in line connectors typically the probe to extension cable connection are properly sleeved or insulated from l
7. 2 Nominal High 3 2 1 0 866 0 895 0 924 2 0 930 0 961 01992 3 0 994 1 027 1 060 4 1 058 1 093 1 128 13 Whenever possible the combination of system cable and added capacitance should be such as to replicate as closely as practicable the above frequency separations gt 50 kHz if not the frequencies themselves f a mixed system using some channels with compensation modules and some with discrete components is planned extra effort to replicate the frequencies should be made The values of C and R that are required cannot be easily predicted but will become apparent during testing with actual hardware refer to the Creating a custom ECP library section gt page 12 for an out line of the procedure for determining suitable component values A range of typical values that it is useful to have available is listed in the section discussing the required specification of discrete components In addition the component values used in the compensation mod ules themselves provide at least an indication of typical values Note that the added capacitance required to achieve the same oscillation frequency in 10 m systems as compared to 5 m reduces as the additional cable introduces capacitance What specification of discrete components should be used Where individual leaded components are being used rather than pre assembled and potted compensation modules the following specifications can be used as a guide e Resistors M
8. 6 3531 Web www skf com cm For technical support contact e TSG Americas skf com North America South America and Asia or e TSG EMEA skf com for customers in EMEA region Europe Middle East and Africa aKF Library Qi ig TISERE Qi ENEN ae MA 65 05m 4140 080mil 5001 MA 65 05m 4140 080mil 500 MA 65 05m 4140 080mil 500 MA 65 05m 4140 080mil 500 MA 65 10m 4140 080mil 600 MA 65 10m 4140 080mil 600 MA 65 10m 4140 080mil 600 MA 65 10m 4140 080mil 600 MA 68 05m 4140 090mil 900 MA 68 05m 4140 090mil 900 MA 68 05m 4140 090mil 900 MA 68 05m 4140 090mil 900 WNP WNP WN MA 68 10m 4140 090mil 10001 MA 68 10m 4140 090mil 10002 MA 68 10m 4140 090mil 10003 MA 68 10m 4140 090mil 10004 Table A1 15 The Power of Knowledge Engineering Drawing on five areas of competence and application specific expertise amassed over more than 100 years SKF brings innovative solutions to OEMs and production facilities in every major industry world wide These five competence areas include bearings and units seals lubrication systems mechatronics combining mechanics and electronics into intelligent systems and a wide range of services from 3 D computer modelling to advanced condition monitoring and reliability and asset management systems A global presence provides SKF customers uniform quality standards and worldwide product availability Please contact SKF USA Inc Condition Monitoring Center San Diego 5271 View
9. Application Note SKF Multilog On line System DMx Internal drivers Contents OVERVIEW ss incite uo Beane a hives een Nhat PARR ad chee PoE Ue ees 3 An introduction to SKF Multilog DMx internal drivers 0 0 0 c ccc eee eee ee 3 SOWIE arean aE Sree beh EE ste jabs E taste oe apane Sacer aude use Goh ea EE E 3 Compensation Modules nesirgo ei doers des dr naaandwned dante aw aa 3 ECP liBra eSa 3 cc5ac0k iicgetcteatadd aad oud thew Rhaed 24 Mea E E NEEE ERER 4 The SKF Multilog DMx Sales Tool 0 ccc cece eee e nee eens 4 Assembling A Syste seirena dah Pied aca gendodd Geass Cae aod Gaede ean eae 4 Commissioning a standard system 00 000 c cc cece eee 5 Fitting the probe extension cable and compensation modules 000005 5 Loading the library s sses hdd eveiee boar cbse EE EE O eed eadia ENE AEAEE 5 Configuring the channel and associating the library 1 2 0 ccc cece eee eee 5 Infinite Gap calibration eunen e denetd nes a E cae edad eens bmn aes 6 ECP calibration Curves e snertne eia e pba eda PARERE bes Hy cade Leek eed T Maintenance and troubleshooting 0 00 0 cece cece eee eee 10 ROWING TAIMLEMANCE s ece 2 55 sic eserini aod dae diem a dodra gute as DRENERE E ES aad aed 10 An infinite gap calibration cannot be achieved 0 0 0 ccc cece ee eens 10 The infinite gap calibration is not stored 6 ccc cece eee nee eens 10 When might an infinite gap calibration have to be r
10. be working con sider checking whether the SKF Multilog DMx internal 5VA1 To confirm this power supply is still present and correct Fig 12 DMx ECP Data dialog e Power off the SKF Multilog DMx module or remove the electronics The loss of this supply may be temporary the internal protection cir module from its base cuit has momentarily activated then latched or permanent some e Short out any ECP inputs that are open no probe connected failure is preventing the internal protection circuitry from resetting e Remove external wiring to the tacho or logic inputs if any on a power cycle Symptoms of a loss of supply may be as follows e Power on the SKF Multilog DMx module or reinstall the electronics module e Incorrect Internal ECP operation possibly positive gap voltages e Finally measure DC volts between terminals 38 and 54 the tacho reported input e ACMMA 9910 module being reported as a CMMA 9920 module e Ifthe measured voltage is about 5V and the internal drivers are e Probably also experiencing tacho failure now OK then the trip was temporary and the latched condition has been successfully reset e f a value very different from 5V is measured probably lt 1V then the conclusion is that the SKF Multilog DMx has suffered an internal hardware failure and will need to be replaced aKF 11 When a system is not entirely standard When is a custom ECP library required Even if there are suitable compensation m
11. ctual target material The end user will usually ask the system provider installer to provide a calibration curve for each channel It will require that the probe is mounted in a probe gapper so that the probe target gap can be adjusted in increments and measure ment data can be stored at each point In SKF Multilog DMx Toolbox the curve acqui sition process is initiated from the ECP Tools tab e Linearization Curves the dialog in fig 6 then displays aKF i DEX 5 ae 802693 8 COMP O8 Y 3009 0 2484 0 2411 naii Comp iB Y 3 4 5 328 ae Comp I5 X 6 7 8 10 05 12 11 09 2008 0 2496 00 13 1401 01 2000 Ev eean fu ar 13 17 32 47 15 10 2008 9 17 03 25 15 10 2008 se s 5 pa 933464 8 x 10 17 32 47 15 10 2008 DIM STO 933698 5 12 17 32 47 15 10 2008 xaz eree Rae 933698 5 ir DMSTD 2 02533 _ 953698 5 14 17 32 47 15 10 2008 tes sm 3 0 2633 933698 5 15 17 32 47 15 10 2008 DMSO 4 0 2633 933698 5 16 17 32 47 15 10 2008 302 is oss s aias oss 5 533598 5 Dek Fig 5 DMx ECP Calibration Location Management dialog ECP Linearized Curve Data Ac quisition m PT ee as es ee ACK aay Sat Feb 14 2009 a140 100 0 pF 4 020 kOhm Fig 6 ECP Linearized Curve Data Acquisition dialog On completion this utility provides an Excel based calib
12. e and frequency data have very low val ues and are not responsive in the expected way refer to the section One or more internal drivers do not appear to be working properly gt page 11 and check that the SKF Multilog DMx internal power supply protection has not been activated 10 The infinite gap calibration is not stored Infinite gap calibrations for a directly attached ECP are stored against the channel number library index and probe reference If anew set of calibration data is to be stored the SKF Multilog DMx will first check to see if an existing calibration can be over writ ten If all three parameters match that record will be updated if no matching record is identified then an empty record will be used An empty record is defined as one for which there is no corre sponding library loaded within the four library locations available Given that there are 16 calibration locations the likelihood of there being no record that is either free or is to be updated is small The possibility remains however that there may be situations where all 16 records appear committed and where manual interven tion will be required to clear a space In such circumstances use SKF Multilog DMx Toolbox to manage the calibration locations deleting at least one record to allow a fresh infinite gap calibration to be stored The location of the free record within the list is unimportant When might an infinite gap calibration hav
13. e to be redone As an infinite gap calibration enables the SKF Multilog DMx to calcu late linearization coefficients that are optimized for the actual probe extension cable compensation module and SKF Multilog DMx chan nel hardware it is recommended that if any of these need to be changed then the infinite gap calibration data should be refreshed What if an infinite gap calibration is not possible If an infinite gap condition cannot be physically achieved it may be permissible to continue to use the earlier data or to perform infinite gap calibration using spare sensor components while accepting that there may be some accuracy degradation due to manufacturing tol erances between the exchanged parts Common reasons why an infinite gap calibration is not possible include e Arunning repair activating a redundant probe changing exten sion cable compensation module or SKF Multilog DMx module Use existing data e No existing data probe already installed Use spare probe ideally from the same manufacturing batch for infinite gap calibration Any changes should be like for like If the probe type or extension cable length and compensation module is changed a fresh library and a new infinite gap calibration will be required aKF One or more internal drivers do not appear to be working properly eB m on es ae ee ee ee ee eee Tee WARRENA SKE MUNlogO Mx Teelnen or EAM a fT SKF Multilog DMx Manager
14. edone 0 c cece eee 10 What if an infinite gap calibration is not possible 2 2 cece eee 10 One or more internal drivers do not appear to be working properly 005 11 When a system is not entirely standard 2 0 0 0c eee eee 12 When is a custom ECP library required 0 0 ccc ccc cect een eens 12 What is an extended range application 0 ec cece cence teens 12 Creating a clistom ECP UIDTAlYy iuscscaskesaaneaten tots ats areas a e An E A ae ened 12 What if compensation modules are not available 0 cee eens 13 What are discrete componentS 0 0 ccc ccc cence narrer urranna 13 What determines the values of the discrete components 00 eee eee eens 13 What specifications of discrete components should be used 00 cee eee 14 Appendix A SKF compensation modules and libraries 15 TECH IGAL SUpPPOT es secs sycic sue dusi aden ace 4 spsadeaicacesl aoa argataseaigod aurrera dup Ragneaneh a iaedaters ue 15 aKF Overview An introduction to SKF Multilog DMx internal drivers A traditional single channel eddy current probe ECP driver is specifically ordered pre matched and pre calibrated to a particular probe type tip coil size system length measurement range and target material Contrast this with an SKF Multilog DMx module where the inter nal drivers have been kept fully general consistent with the theme of configurability that
15. etal film 0 1 tolerance 15 ppm temperature stability 0 25 W Example Welwyn RC55Y precision resistor Typical range 3k70 4k02 4k22 4k53 4k75 5k11 5k23 5k49 5k76 6k04 6k19 6k49 6k98 7k50 8k06 10k0 11k0 13k0 16KO The influence of resistance values much greater than 16k is usually small and little different from leaving the resistor out infinite resis tance added e Capacitors COG ceramic 100 V Example Murata radial COG ceramic Typical range 10 pF 22 pF 33 pF 47 pF 100 pF 150 pF 220 pF 270 pF 330 pF 470 pF 560 pF Preferably a 5 mm pitch and avoid any with a very short lead length pitch and lead length only so as to fit the SKF Multilog DMx termi nals more easily Also avoid any component types that are unmarked COG is an EIA three character code for a ceramic dielectric material with the lowest capacitance temperature dependence Same as NPO type 14 Component values Table 2 CMSS 65 5 m 16 4 ft system Channel number Capacitance pF al 650 330 220 100 2 540 270 270 3 403 220 150 33 4 330 Component values Resistance kQ TO 7 87 6 34 5 49 Table 3 CMSS 65 10 m 32 8 ft system Channel number Capacitance pF il 330 2 220 3 100 4 0 Component values Resistance kQ 51 00 15 00 8 66 6 34 Table 4 CMSS 68 5 m 16 4 ft system Channel number Capacitance pF
16. hey will usually consist of two separate discrete components a resistor and a capacitor fitted to each channel The capacitance influences the frequency of oscillation e Higher added value results in lower oscillation frequency same as a longer extension cable The resistor is then used to achieve voltage levels in an optimum range e Lower resistance value added reduces the voltage at the input Highest voltages are to be found when no resistor is fitted Note that this does not correspond to zero added resistance but to an infinite value of added resistance The SKF Multilog DMx base provides two duplicate sets of terminals for the ECP inputs ECP1 17 18 1 2 ECP2 21 22 5 6 ECP3 25 26 9 10 ECP4 29 30 13 14 Be aware that while the two sets of terminals allow one capacitor and one resistor to be added without doubling up on any of the ter minals the range of component values available capacitors espe cially may mean that two rather than one capacitor have to be fitted to achieve an optimum solution aKF Note that to maintain long term reliability of the connection only one wire per terminal one component per terminal pair is recom mended If two components usually capacitors have to be fitted in the same position consider first soldering them together at the cor rect pitch for the SKF Multilog DMx terminals 5 mm to ease han dling and installation What determines the values of the discrete co
17. ies are permanently stored on the SKF Multilog DMx mod ule A maximum of four different libraries can be accommodated at any one time and these can be freely linked to physical ECP chan nels Libraries can be downloaded to an SKF Multilog DMx module from SKF Multilog DMx Manager or SKF Multilog DMx Toolbox e SKF Multilog DMx Manager Module Properties ECP Libraries tab e SKF Multilog DMx Toolbox ECP Tools tab Download ECP Library aKF The help files associated with the software provide further detailed guidance on how to use these features Alternatively the library download can be a part of the channel configuration process as below Configuring the channel and associating the library In SKF Multilog DMx Manager an internal driver ECP input can be chosen by making the following selections from the General tab of measurement channel properties e Transducer type Displacement e ECP Type Direct ECP An eddy current tab is now enabled and from it e The active library can be selected Or the library can be downloaded if not already present using e Load ECP library from file and then activated There is a user descriptive field for Probe Reference Information which the user should complete Ideally this would contain the probe serial number or other reference to the actual probe that will be fitted The user manual and help files associated with the SKF Multilog DMx Manager software provide further detai
18. led guidance on how to use these features Where a channel is already suitably configured it can also be associated with its library or the association changed using SKF Multilog DMx Toolbox e ECP Tools tab Link Library to Channel The linked library should be the one that has been specifically developed for that channel Note If ECP type Direct ECP is not available check the module type and channel number On a CMMA 9920 internal ECP drivers are only available on channels 3 and 4 Infinite gap calibration An infinite gap calibration can be performed using either SKF Multilog DMx Manager or SKF Multilog DMx Toolbox Key prerequisites for both are identical e The channel must be properly configured as Displacement Direct ECP type e There must be a library associated to or linked to that channel e The probe extension cable and compensation module must be installed e The probe must be positioned in free air no target present En e As per best practice all other ECP chan nels must be fitted with their probes and compensation modules or their inputs shorted With these in place the infinite gap calibra ECPupoad0K_ _ OO O tion process can begin In either software the process is similar and follows the follow ing general steps Fig 3 Calibrate dialog e An automatic check that the prerequisites are in place e Reading of the library file and displaying some relevant i
19. mponents As additional protection against cross talk the added compensation components should be used to provide frequency separation between channels to avoid that any modulation or beating between them might appear as a genuine signal Therefore typically when the same probe systems are fitted to all channels the compensation components fitted to each channel will be different Slight exceptions to the above can occur where 1 The probe systems are already different say one at 5 m and one at10 m Here added capacitance if any should maintain or reinforce the difference in frequency 2 There are 15 m systems where due to the inherent high system cable capacitance no added capacitance is possible Here deploy only one 15 m system per SKF Multilog DMx or use nominal 15 m systems where the actual system cable lengths are gt 10 m 32 8 ft but different between the channels Added resistance may still be required to optimize signal levels 3 Tacho channels ECP3 or ECP4 Here compensation components are still advised but no library is required as no digital linearization is taking place The compensation modules are similarly designed to achieve fre quency separation between the channels while supporting mixed use of the channels different probe systems on different chan nels The target frequencies for each channel are as follows Table 1 Target frequencies Frequency MHz Channel number Low 3
20. ndividual discrete components can now be avoided by using SKF manufactured compensation modules Because SKF compensation modules are potted they provide improved environmental and mechanical protection as compared to a solution that uses discrete components Fig 1 Compensation modules fitted on SKF Multilog DMx ECP inputs 3 and 4 These compensation modules contain the specific component values required for a particular combination of SKF Multilog DMx ECP chan nel connected probe type and system cable length For easy identifi cation three of the compensation module faces are marked to indi cate e Generic probe type for example SKF CMSS 68 e System cable length in meters 10M e Intended SKF Multilog DMx ECP channel 4 The corresponding compensation module part number for the above example would be CMMA 968 10 4 Appendix A gt page 15 provides a list of available compensation modules or identify the correct compensation module by using the SKF Multilog DMx Sales Tool spreadsheet ECP libraries The processing required to linearize the probe signal will vary depending on the target material the probe system i e cable length and the measurement range Any particular ECP library will reflect specific requirements in these areas and the compensation module that has been fitted You will need to download libraries one for each channel where an SKF Multilog DMx internal driver is in use to the SKF Multilog DM
21. nforma M DMx ECP Data tion to the user e Allowing a period of signal settling after the calibration is initiated e After settled and when judged valid the user can finalize the calibration In SKF Multilog DMx Manager the infinite gap calibration process is initiated from the Eddy current tab of measurement channel properties e Calibrate Probe the dialog in fig 3 then displays In SKF Multilog DMx Toolbox the infinite gap calibration process is initiated from the ECP Tools tab e Calibrate ECP Channel the dialog in fig 4 then displays Fig 4 DMx ECP Data dialog 6 aKF It is generally useful to separately maintain a record or backup of the infinite gap calibra tions that have been performed Backup export or export all and a range of calibra tion management functions can be accessed via SKF Multilog DMx Toolbox Select the ECP Tools tab calibration management to access these facilities SKF Multilog DMx Toolbox s on line help provides further details on the functionality Before putting the probe into service it would be normal practice to run a probe curve ECP calibration curves Running a probe curve should exercise the system over the required measurement range with ideally a representative sample of the actual shaft material to show that it meets the application requirements It is an important step in the process as it proves that the library is accurate for both the probe and the a
22. ocal ground e Check the tightness of the screw terminals to which compensation module or discrete components are fitted During more intrusive maintenance removal or replacement of probes extension cables power down or remove the SKF Multilog DMx as per best practice see the Assembling a system section gt page 4 In all cases follow any site specific requirements for system over ride and or isolation before commencing any maintenance on the SKF Multilog DMx system An infinite gap calibration cannot be achieved The infinite gap calibration process includes checks by software that the oscillation frequency and amplitude is within the limits of the library The most common reasons for a failure to calibrate are as follows e Incorrect combination of probe extension cable compensation module or library e Initiating a calibration when the probe is not in free air e Incorrect placement of the compensation module or loose wiring e Insecure coaxial connection probe to extension cable or extension cable to SKF Multilog DMx base e Defective probe or extension cable Double check all the above before proceeding f no fault can be found in the setup that might explain a failure to achieve an acceptable infinite gap calibration then this suggests that the library is not suitable for the actual hardware being used In these circumstances consider creating a custom library for this channel If the infinite gap amplitud
23. odules available a custom library may still be required in the following circumstances e There is no default library available for these systems e The target material is different from the default library e The required measurement range is different from the default library extended range application For systems where compensation modules are not available custom libraries and usually also discrete compensation components will always be required What is an extended range application The maximum measurement range of an ECP system is ultimately limited by the diameter of the coil in the probe tip The standard or published range of a traditional ECP system is one that can be achieved by any example of that type while meeting relevant accu racy requirements An extended range application is one where a custom SKF Multilog DMx library is created to maximize the usable range of a particular probe For a CMSS 65 5 mm probe this might extend the usable range from 80 to perhaps 100 mil The larger the probe the better the potential for decent extended range performance but always at some cost increase in ISF or DSL errors must be expected A judg ment has to be made in each case as to whether the trade off between range and accuracy is acceptable Note that extended range applications with gaps greater than 120 mil at a nominal sensitivity of 200 mV mil will result in gap volt ages greater than 24 V being reported This i
24. ool aKF Commissioning a standard system Fitting the probe extension cable and compensation modules By default the SKF Multilog DMx base CMMA 9000 is delivered with short circuit jumpers installed for each ECP input It is strongly recommended that these short circuit jumpers are left in place for any ECP channels that are not being used This can also include channels 1 and 2 of a base that is being used with an SKF Multilog DMx CMMA 9920 There is no ECP channel 1 or 2 on a CMMA 9920 but the links will do no harm The following sequence of activities is advised for SKF Multilog DMx installation and ECP system installation 1 Power down the SKF Multilog DMx or remove the electronics module from its base 2 Install the eddy current probe and extension cable to the designated ECP input at the coaxial SMC connector 3 Remove the default ECP short circuit jumper from the designated ECP terminals ECP1 17 18 ECP2 21 22 ECP3 25 26 ECP4 29 30 Only remove short circuit jumpers on the channels where probes have been connected 4 Install appropriate compensation modules at the terminal block locations where the jumpers have been removed 5 Re power the SKF Multilog DMx or reinstall the electronics module Adherence to the above procedure will minimize the possibility of a nuisance trip of the internal SKF Multilog DMx ECP power supply and or more permanent damage to its circuits Loading the library ECP librar
25. range that at infinite gap with the appropriate capacitance fitted the output voltage is in the range 100 to 350 mV Process Create ECP Library Process Overview Fig 13 Create DMx Eddy Current Probe Library dialog 12 aKF e f the voltage is too high it can be reduced by fitting a resistor or if one is already fitted reducing its value If the voltage is too low either remove or increase the value of any resistor that has been fitted Before attempting to create custom libraries where no compensation modules are available a sufficiently good range of suitable quality discrete components must be on hand refer to the following sections Where multiple libraries corresponding to differing ranges might be needed consider collecting the non linearized data over the lon gest range required That measurement data automatically stored in an Excel file can then be post processed by SKF Multilog DMx Tool box as when required to produce libraries optimized for shorter ranges without needing to acquire further measurement data from the actual probe What if compensation modules are not available When deploying probe systems for which compensation modules are not available discrete compensation components and custom libraries will be required What are discrete components Discrete components offer a way of accommodating probe types or system cable lengths for which compensation modules may not be available T
26. ration report that summarizes the calibration check and shows how well the measurement setup performs Eddy Probe Calibration SKF Reiability Systems Customer Customer Name Asant Plant Into Gap in allbration per API 670 4 Edition Section 7 3 2 1 PROBE CALIBRATION GRAPH amp E gt a Oo 50 60 POS TION INPUT poll SKE nstalled Locaton Probe Probe IDVSN Probe Type Probe Clameter System Langt Target Material Ext Cable MoI No Serlal Mo Modal No eral No ECP Channel Sensit ty Library ID Linganzation Range Compensa ton Calculated Data Sensitivity Position offset Sat Feb 14 2009 Machine Reference Location lito Poke Feti CMSS58 Smm 10m 4140 cmas type ExtSvN CMMASEHO 01396157 005005 a 200 Om vnl 1 60 NA igo 0 m vi anil 0 4 mil DSL mil Fig 7 Sample Calibration Report aKF The two key measures of accuracy are Deviation from a Straight Line DSL and Scale Factor Error SFE While both measures are inde pendently graphed with their API670 acceptance limits marked in red they share interdependency such that adjustments to the sensi tivity value away from the nominal value can be used to minimize the position error Fig 8 shows just such an example where a modifica tion to the sensitivity reduces the DSL to within 0 25 mil across the working
27. ridge Court San Diego California 92123 USA Tel 1 858 496 3400 Fax 1 858 496 3531 Web www skf com SKF and MULTILOG are registered trademarks of the SKF Group Excel is a registered trademark or trademark of Microsoft Corporation in the United States and or other countries All other trademarks are the property of their respective owners SKF Group 2013 The contents of this publication are the copyright of the publisher and may not be reproduced even extracts unless prior written permission is granted Every care has been taken to ensure the accuracy of the information contained in this publication but no liability can be accepted for any loss or damage whether direct indirect or consequential arising out of the use of the information contained herein SKF reserves the right to alter any part of this publication without prior notice SKF Patents include US04768380 US05679900 US05845230 US05854553 US05992237 US06006164 US06199422 US06202491 US06275781 US06489884 US06513386 US06633822 US6 789 025 US6 792 360 US 5 633 811 US 5 870 699 WO_03_048714A1 PUB CM3156 1 EN January 2013
28. s available requires some careful planning before attempting to create a library e At what frequency shall the channel operate e Will there be sufficient separation to other ECP channels on this module It is recommended that during custom library generation all chan nels other than the one for which the library is being prepared are shorted The initial assessment of the infinite gap oscillation amplitude and frequency will now comprise several steps e First determine the capacitance required to achieve the target oscillation frequency noting that increasing added capacitance lowers the frequency reducing the added capacitance increases the frequency e The added capacitance will also affect the infinite gap voltage but at this point the focus should be on achieving the required oscilla tion frequency e lf two capacitors are required connecting them in parallel sums their capacitance Cota pF C1 pF C2 pF e Secondly optimize the voltage level The non linearized voltages are unlike those that might normally be associated with ECP sys tems The measurement range is 400 mV absolute maximum and in any setup infinite gap will produce the highest most posi tive voltage e For standard measurement ranges 80 100 mils an infinite gap voltage between 100 mV and 250 mV is recommended e For increased range applications an infinite gap voltage between 250 and 350 mV is recommended e n general the aim is to ar
29. s of no consequence to the SKF Multilog DMx and the TX OK window can be extended to accommodate the higher negative voltage values Creating a custom ECP library The simplest situations to deal with will be where compensation modules are available for the selected probe system but a custom library is required perhaps because of a different target material or measurement range requirement etc Custom ECP libraries are created using SKF Multilog DMx Toolbox and the process is initiated from the ECP Tools tab e Create ECP library the dialog in fig 13 then displays E Create DMx Eddy Current Probe Library Once an initial assessment of the infinite gap oscillation amplitude and frequency has been made the process will require that the probe is mounted in a probe gapper so that the probe target gap can be adjusted in increments and non linearized measurement data can be stored at each point The software will analyze that data to provide a library that will satisfactorily linearize the probe output The help files associated with the software provide further detailed guidance to the user on this process Once the custom library is available the process of commissioning the system follows that of a standard system e Load the library and associate it e Instigate an infinite gap calibration e Check performance with an ECP calibration curve Generating a custom library for probe systems for which there are no compensation module
30. section The SKF Multilog DMx Sales Tool The SKF Multilog DMx Sales Tool is a spreadsheet that provides guid ance as to what components and accessories are needed to assem ble a complete SKF Multilog DMx system This includes ECP related elements Compensation modules and Standard libraries as well as power supply communications and relay output hardware Compensation modules are designed to operate with special cut to nominal length extension cables The correct part numbers for these extension cables designated by a D code in the length field are included in the SKF Multilog DMx Sales Tool For the latest version of the SKF Multilog DMX Sales Tool please contact CMC San Diego Customer Service Group Assembling a system For each channel using an internal SKF Multilog DMx driver verify that the following information is known 1 Target SKF Multilog DMx channel number 2 Probe manufacturer and type 3 System cable length 4 Target material 5 Required linearized measurement range Based on 1 2 and 3 check to see if a compensation module is available e If not then discrete components will have to be sourced by you and a custom library will have to be developed by you Is the target material confirmed as AISI 4140 steel e If not then a custom library in required Based on 1 2 3 4 and 5 check to see if an existing library is available e If not then a custom library will have to be developed by you If
31. x module before the system can be put into service The library files file extension ecp contain reference information on how the library and the linearization coefficients have been derived specific setup information for the module to execute probe calibration and acceptance limits to validate the initial probe system calibration process Although the format of all ECP library files is the same two library types are defined for use with the SKF Multilog DMx module 1 Default ECP libraries These are libraries provided by SKF for standard SKF probe and extension cable combinations Default libraries are generated using an AISI 4140 steel target and will have indices in a reserved range between 1 and 10999 Appendix A gt page 15 includes a list of available default librar ies or you can identify the appropriate library index by using the SKF Multilog DMx Sales Tool spreadsheet The available default ECP libraries are included in the SKF Multilog DMx Data Sources Install and will be copied to the folder SKF DMx StdLib 2 Custom ECP Libraries These are user generated libraries that are allocated an index between 11000 and 65534 Custom librar ies may be used for example when no standard library exists to optimize accuracy for a specific probe system or shaft material to accommodate special or unusual circumstances and for non SKF probe types The procedure that allows a user to create libraries is described in a later
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