Introduction

2. Introduction • Maintenance cost is a significant part of total expenses • Importance of condition monitoring (CM) • Up to1/3 of all maintenance cost ineffectively wasted • Unnecessary maintenance • Improperly carried out maintenance • CM with diagnostics allow maintenance based on current condition • 40% of failures of el. motors caused by bearings

3. Objectives • Find feasible concept for bearing CM • Specify the requirements for the concept • Design reliable testing platform

4. Industrial Information Infrastructure • Embedded sensor situated at field level • Analysis including feature extraction and diagnosis done locally by embedded sensor • Communication busses at all levels • Possibility to monitor and control the plant globally through internet

5. Embedded Analysis Concept Requirements • System must be easily incorporable into existing infrastructure • Key issues: reliability and efficiency • Embedded sensor suppose to be a stand-alone system • Whole CM algorithm has to fit into the embedded sensor

6. Diagnostics Algorithm Requirements • Detect departures from normal behavior • Single-point defects (characterized by unique spectral components) • Generalized roughness (characterized by broadband increase in bearing vibrations) • Alarm of future damage if no action is taken • Fault must be detected at time when the machine can still be safely used

7. Diagnostic Algorithm Requirements (Ex. 1: Vibration Patterns of 9-ball Bearing) • Case b) might eventually be misclassified as one larger defect a) One scratch in inner race b) Two scratches in inner race

8. Diagnostic Algorithm Requirements (Cont.) • Stochastic nature of defect grow • Parameter changes – mech. damping, speed, torque load, degree of unbalance, etc. • Flowing fluids (water, steam, etc.) can also induce vibrations

9. Diagnostic Algorithm Requirements (Ex. 2: Effect of Lubrication) 9-ball bearing with 1 scratch in outer race, and 2 scratches in inner race • Peak due to the inner race fault decreased by more than 70% • Increase in bearing vibration may indicate malfunction of lubricating system a) Standart lubrication b) More grease applied

10. Hardware Requirements • High processing capacity • Minimal power dissipation • Sensitivity • 12-bit A/D conversion • 32-bit floating-point number representation • Memory • Sampled data and analysis (SRAM, SDRAM) • History recording (Non-volatile type)

11. Hardware Requirements • Communication link • Environmental stresses immunity • Electromagnetic interference • Mechanical stresses (vibrations) • Climatic stresses (high temperature, humidity)

12. Developed Pilot System

13. Developed Pilot System (Cont.) • DSP based testing platform

14. Developed Pilot System (Cont.) • Envelope spectrum analysis algorithm implemented • Tests in laboratory environment approved suitability for CM tasks • The pilot system is currently in testing run in Lappeenranta water plant, and is controlled remotely via GSM-modem connection

15. Future Objectives • Install the developed DSP based platform to industrial plants • Collect statistically significant number of measurements • Develop reliable diagnostic algorithm • Implement the algorithm into the DSP platform • Test the embedded sensor in industrial environment

16. Summary • Motivation for condition monitoring • Embedded analysis concept • Requirements • Embedded analysis concept • Diagnostic algorithm • Hardware • Developed pilot system