Vibration sensorsPresentation

ContentsVibration definitionCharacteristicsTypes Shock pulse transducersAllen bradley accelerometer

What is VibrationAny motion that repeats itself after an interval of time is called vibration or an oscillation. The cyclic or oscillation motion of a machine or machine component from its position of rest.

THEN WHY ONLY VIBRATION?All machines vibrate. Every machinery defect generates its own unique vibration frequency. An increase in vibration indicates of a developing problem.

COMMON CAUSES OF VIBRATIONMisalignmentUnbalanceLoosenessDefective BearingsResonanceElectrical ProblemsAerodynamic / Hydraulic Forces

Vibration applicationsCompressorBlowerSag mill and Ball mill motor, reducer and pinionCrusher motor inner/outer pinion shaft

CHARACTERISTICS OF VIBRATIONAmplitude Displacement Units are mils or microns(1 micron = 0.001mm or 0.039 mils.Velocity Units are in/sec or mm/secAcceleration Units g. Where 1g=32.2ft/sec2 or 9.81 m/sec2.Spike Energy gSE, HFD,SEEFrequency Hertz(CPS), CPM or OrdersPhase Relative Motion Degrees or Clock

Crusher pinion shaft vibration sensor module The SPM module scale is based on the Shaft diameter and RPM chart provided for the BDM-40 display module:dBsv is decibel shock value 0 to 80dBsv range (5bBsv/mA, 0.2mA/dBsv)Shock pulse transducer with 100dBsv is connected to this module

BDM-40 scale for a 60-89AnalogValueLevelDisplay Module15 to 20mA55 to 80 dBsvAlarm Level Red Alarm light on12 to 15mA40 to 55 dBsvWarning Level Yellow Alert light on4 to 12mA0 to 40 dBsvOK Green OK light on8mA20 dBsvNormal Operation typical Level

Rpm vs shaft dia

9200AT Accelerometer Provision for both vibration and temperature measurementSensitivity 100 mv/gMeasuring range -50g to +50gFrequencey range 0.5 to 6500HzOutput bias voltage 8 to 12VDC

Common Machine Defect Frequencies1xRPM - Unbalance2xRPM - Misalignment or LoosenessElectrical Line FrequencyBlade or Vane Pass Frequency BPF = # of vanes or blades x RPMGear Mesh Frequency GMF = # of Gear Teeth X gear RPMBearing Defect Frequencies

WHAT IS AN FFTFast Fourier Transform. Also known as a Spectrum or as the Frequency domain. Graph of Vibration Amplitude vs. Frequency. Also known as Signature All frequencies in a chosen range are separated and displayed as individual peaks each having its own amplitude. Most useful tool for analysis. Named after French mathematician Baron Jean Baptist Joseph Fourier

SPIKE ENERGY. WHAT IS IT?A measurement parameter designed to detect low amplitude transient impacts generated within the Audiosonic/Ultrasonic frequency range by microscopic surface flaws in rolling element bearings and gears.

SPIKE ENERGYSpecial amplitude parameter obtained using special filters. First indication of a problem in the rolling element bearing. Special circuit detects very high frequency, short duration pulses of energy generated by defects such as nicks on the raceway.

HOW IS IT MEASURED ?The acceleration signal is processed via a high pass filter and a peak detection circuit to produce a numerical value which is the product of :- The Number and amplitude ( Intensity ) of the impacts in a unit of time. The value is expressed in units of gSE

Module for vibration

Vibration sensor