The art of instrumentation 09 2005

The Art of Instrumentation & Vibration Analysis Back to the Basics – Forward to the Future Our Objective… • The objective of Condition Monitoring is to provide information that will keep machinery operating longer at the least overall cost – What it is NOT: • • • Establish new measured point records Means to show analytical brilliance The answer to every problem! Back to the Basics… • Vibration – Simple Harmonic Motion • • Oscillation about a Reference Point Modeled Mathematically as… x(t ) = X sin ωt Back to the Basics… Period, T Unit Circle RMS 0 to Peak Peak-to-Peak Back to the Basics… • Basic Signal Attributes – Static • • Slowly Changing Temperature • Basic Signal Attributes – Dynamic • • Sensor must respond in fractions of a Second Vibration, Amperage, Pressure Back to the Basics… • Dynamic Signal Fundamentals – – – – Amplitude Frequency Timing Shape • Timing, or Amplitude Frequency Signal Shape –Phase Proportional by Determined Waveform to theSimple severity ofby reciprocal of – •Represented vibratory Period motion •the time delay Complex CPS or two Hzas – •between Pattern Expressed Recognition ••signals RPM Peak to Peak Orders – ••Leading Zero to Peak RMS – •Lagging Peak and RMS Comparison Relationships of Acceleration, Velocity and Displacement The Big Picture Sensor(s) Cables Data Acquisition & Storage Signal Conditioning Communications Remote Analysis and Diagnostics Displacement Sensors • Elements – Probe, matched extension cable, Driver Spectral Integration • Where does the “SkiSlope come from? – Integrating Acceleration to get Velocity pops out a constant value, which is manifested as a “DC” component because it has no frequency dependence! Spectral Integration • How we solve this problem? Spectral Integration • Truth is – we can’t! – • It’s PHYSICS! What we can is… – “Zero” the first or so Spectral Bins! Spectrum Analysis • Machine Component Condition – Identified by Frequency – Severity Indicated by Amplitude – Rate of Deterioration Indicated by Spectral Comparison over Time Spectrum Analysis Waveform Analysis • Pattern Recognition is Key – Requires understanding of Machine Components • • Gearbox Bearings Waveform Analysis Orbit Analysis Transient Analysis • • • • • Long-Term Time Waveforms Bode – Nyquist Plots RPM vs Time Waterfall Plots Cascade Plots Machine Transients Vibration Severity • When I make the call? – – – – Alarm Levels Fault Levels Do you use GM, API, ISO Guidelines? Risk vs Reward Communications • Area of Greatest Technology Progress – – – – • Email, FTP, Internet (High Speed) Industrial Ethernet Wireless Phone, Modem, Ethernet Satellite Digital Revolution! (Remote Desktop) Communications Analysis and Diagnostics • Area of LEAST Progress – Not Fundamentally Changed in 20 years – Personnel Downsizing – not going to come back, either – What is a Vibration Analyst’s Career Path? • • In-house are becoming contracted services Constant re-training to solve yesterday’s problems! Analysis and Diagnostics • Will Technology come to the Rescue? – – – Remote, centralized Diagnostics Rapid Service Company Growth Rapid Growth in Wireless Sensor Technology has Cooled • • Power Supply Problem Spawned new VC-backed Research Companies