The Modal Shop, Inc. A PCB Group Company

Transcription

1 The Modal Shop, Inc. A PCB Group Company

2 Measurement Sector Systems Sector

3 The TMS/PCB Relationship o PCB Focuses on Components and Sensors Accelerometers Microphones Pressure Sensors Signal Conditioning o TMS Fulfills the Application Needs of Customers with System Solutions Calibration Systems Structural Test Systems and Accessories Rental of Test and Measurement from PCB Group Process Quality Systems for Nondestructive Testing

4 About The Modal Shop o More than 20 years in operation applying structural dynamics and test knowledge to create innovative products and systems o Deep application knowledge partnered with PCB products o Strong relationships with leading University researchers around the globe o Contributors to Standards committees TEDS Transducer Electronic Data Sheets (TEDS) TC108 Mechanical Vibration, Shock and Condition Monitoring

5 PCB Group Calibration Expertise o PCB Piezotronics (Buffalo, NY) Jeff Dosch, Ph.D., sensor and calibration exciter design Stephen Bill, TMS Consultant, 45+ years in test and measurement including many years with PCB Piezotronics and Endevco Chad Walber, Ph.D., Noise & Vibration Test & Measurement Engineer o PCB West Coast Design Lab (San Clemente, CA) Bob Sill, Sr. Scientist, former Endevco calibration system and shaker architect o TMS Calibration System Products (Cincinnati, OH) Mark Schiefer, Sr. Scientist, integrator of TMS Laser Primary

6 Calibration Overview o What is calibration? Verifies amplitude response and system linearity over the intended range of use Provides physical meaning to the electrical output Typical calibration includes: Reference sensitivity Frequency response Output bias level or supply voltage Transverse sensitivity Resonant frequency Time constant

7 Calibration Overview o Why calibrate? Ensures the sensor performs according to the specification Often required by ISO quality system or contractual reasons o Why recalibrate? Good measurement practice that helps to confirm accurate results and that the sensor is still healthy Risk vs. reward decision When did the sensor break?

8 Calibration Overview: Standards o What are the standards? ISO 9001 Company Quality Management System ISO Calibration Laboratory Quality System Identifies the general requirements for the competence of calibration laboratories Accreditation bodies include A2LA, ACLASS, NVLAP, etc ISO Methods for the Calibration of Vibration and Shock Transducers Part 11. Primary vibration calibration by laser interferometry Part 13. Primary shock calibration by laser interferometry Part 21. Vibration calibration by comparison method Part 22. Shock calibration by comparison method

9 Calibration Methods o Absolute Methods Tests the sensor when subjected to a known, accurate and reliable standard of nature Drop Test/Gravity Inversion Test Gravimetric Laser Interferometry

10 Calibration: Laser Interferometry o ISO Part 11 for primary vibration calibration o Utilizes fringe counting or direct demodulation Laser method provides primary calibration as it is based on a constant of nature the wavelength of light o Uses expensive measurement instrumentation o Requires relatively large accelerations at high frequencies 25 g at 5 khz; 50 g at 10 khz; 100 g at 20 khz o Provides best, lowest measurement uncertainties

11 Calibration Methods o Relative Methods Test where the sensor and calibrated reference are subjected to the identical input acceleration. The ratio of the output signals provides the calibration factor. Comparison back-to-back Handheld shaker Impact

12 Calibration: Comparison o Test sensor mounts back-to-back with a reference accelerometer that has been previously calibrated by primary means or by a recognized laboratory

13 Calibration: Comparison o ISO Part 21 vibration calibration by comparison to a reference transducer o Most common of all calibration system types, typically used by manufacturers and metrology labs o Reference transducer can be either external piggyback or internal to exciter o Approximate uncertainty, including both systematic and random errors:

14 Transverse motion Flexture base vs. Air Bearing Transverse bending and rocking motion of shaker causes significant measurement error Calibration air-bearing shakers meeting ISO recommendations eliminate this error

15 Calibration Systems in ITRI/CMS

16 Calibration: Shock o Test sensor mounts back-to-back with a reference accelerometer and anvil, struck with a pneumatically operated projectile Test Sensor PneuShock shock tower Reference Accel Anvil Impact Shock

17 Machinery Protection System A Steam Turbine Generator Train Ref. Turbine Supervisory Instrumentation (TSI) An Overview by Ziegler, G. & James, C (SKF)

18 Machinery Protection Systems Example: Turbine Supervisory Instrumentation oallows planned maintenance Provides diagnostics and troubleshooting capabilities Provides warning of impending problems oprotects the turbine from catastrophic failure Ensures safety of plant personnel oreduces the number of turbine run ups & coast downs oextends intervals between overhauls omaximizes turbine availability oprovides automatic shut down of the turbine oimproves the operation of the turbine ointegrates with plant computers and/or maintenance systems

19 Major measurement categories o Motion Measurements Vibration Monitoring Sensors Non-contact displacement transducers: eddy current (proximity) probes Velocity transducers Accelerometers o Position Measurements Eddy current probes used to monitor thrust bearing wear, rotor position, casing (shell) expansion, differential expansion and control valve position o Speed Measurements o Process Parameters Temperature Pressure Flow Sensor calibration is key for good measurements!

20 Traditional Calibration: Comparison o Test sensor mounts back-to-back with a reference accelerometer that has been previously calibrated by primary means or by a recognized laboratory Method is also valid for: Velocity sensors Proximity sensors 4-20 ma Velocity sensors

21 Traditional Transducer Calibration Bring the transducer to the calibration system...

22 End-to-end Calibration Bring the calibrator to the transducer!! Digital Control System Plant Control Room PVC Accelerometer, Velocity, or proximity probe

23 In-situ Calibration Overview o Why in-situ calibration? Confirmation that alarm trip points are set properly allow user to dial the exact vibration level being monitored Check alarm & alert trip points in Digital Control System, Turbine Control Supervisory or condition monitoring equipment o Reference sensitivity check- in the units being monitored: Acceleration & Velocity Displacement Rolling Element Bearings Journal Bearings Eddy Current Proximity Probes

24 Vibration Transducers o Accelerometers Piezoelectric Large dynamic range Wide frequency range o Velocity Sensors Electrodynamic (induced voltage / self generating) e = Blv Larger size Sensitive to orientation Sensitive to magnetic field 1 Mounting Pad (080A118) 2 ¼ -28 to ¼ -28 Adaptor (081B20) to ¼ -28 Adaptor (081A08) o Mounting Can be direct mounted to the shaker table for calibration

25 o Eddy current (proximity) probes Measure displacement 200mV/mil (1 mil=0.001in) or 7.87 mv/μm Bently Nevada (now part of GE) pioneered the use of eddy-current proximity probes for the measurement of vibration in high-speed turbomachinery in the 1960 s and 1970 s. Non-contact displacement measurement Common method to quantify shaft vibration and shaft location in a fluid film bearing (journal bearing) Used in compressors, turbines, pumps, electric motors, generators, and other rotating equipment No moving parts, no wear, works to DC Vibration Transducers

26 Back to our Application Case o Turbine Supervisory Instrumentation

27 Steam Turbine - Typical Radial System

28 Turbine Supervisory Instrumentation o Vibration monitoring locations typically include each bearing at: High, Inter, Lower pressure Turbines Generator Exciter o Vibration is monitored to provide indication of: Unbalance Misalignment Cracked shaft Oil whirl and other dynamic instabilities

29 Proximity Probes Radial Monitor and Setpoints for Alarm and Shutdown (from API 670)

30 Proximity Probes Axial Position (Thrust) Monitor (from API 670)

31 Turbine Supervisory Instrumentation o Surveillance System (safety) Wired to shut the machine off Avoid catastrophic failure o American Petroleum Institute (API) Standard 670 API Standard th Ed Machinery Protection Systems Requires calibration of the proximity probes Provides industry with a means to quantify the shaft vibration and shaft location in a fluid film bearing (journal bearing) to avoid catastrophic bearing failure. The API Standard 670 has global acceptance through active involvement with the International Organization for Standardization (ISO) and other international bodies

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34 Portable Vibration Calibrator Requirements o Provide on-site dynamic verification of a broad variety of dynamic transducers in place: accelerometers, velocity pickups and non-contact displacement transducers o Rugged and portable o Small & Lightweight o Battery powered o Completely self contained, includes sine generator, power amplifier, electro-mechanical shaker, precision quartz reference accelerometer and digital display. o Wide measurement range up to 20 g amplitude / 5 Hz to 10 khz frequency range o Precision closed loop amplitude control

35 TSI Conclusions End-to-end calibration in Machinery Protection Systems oensure vibration sensors, cabling and data acquisition systems are operating accurately Validates the health of an installed monitoring system Validates vibration alarm and trip points oprotect process quality and critical plant machinery ooperation Safety oreduces maintenance and shutdown related costs oover 200 industries worldwide utilize in-place calibration

36 Other Industry? End-to-end calibration is universally applicable oautomotive Manufacturing oaerospace Manufacturing

37 Other Industry? End-to-end calibration is universally applicable oaerospace Operations odefense Operations

38 Other Industry? End-to-end calibration is universally applicable oheavy Manufacturing oenergy Exploration oenergy Production omining

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42 MTS System Sector The Modal Shop Thank you!