Eddy current digital proximity sensing for vibration detection

;)

1. EDDY CURRENT DIGITAL PROXIMITY SENSING FOR VIBRATION DETECTION Presented by : jibunath k S5IE Roll No :15 Reg No : 17080585

2. HEADLINES INTRODUCTION MODEL OF EDDY CURRENT PROBE SYSTEM PRINCIPLE OF DIGITAL PROXIMITY SYSTEM DIGITAL PROXIMITY SENSING FOR VIBRATION DETECTION ADVANTAGES OF EDDY CURRENT DIGITAL PROXIMITY SYSTEM CHALLENGES OF EDDY CURRENT DIGITAL PROXIMITY SYSTEM CONCLUSION 2

3. INTRODUCTION Eddy current proximity sensing is one of the most mature technology. It is used to measure linear, angular metal position, displacement, motion, compression and vibration. Applies in automotive, energy, industrial, medical & communication fields. 3

4. It is a contact less sensing technology. Proximity sensing offers better performance and reliability at a lower cost. 4

5. WHAT ARE PROXIMITY SENSOR ? A proximity sensor is sensor able to detect the presents of near by objects without any physical contact. Proximity sensor include all the sensor that perform non contact detection in comparison to sensor such as limit switch, that detect the object by physically contacting them. 5

6. WHAT IS EDDY CURRENT ? Eddy current are loops of electrical current. The basic principle is Faraday’s law of induction. The electrical current induced with in conductors by a changing magnetic field in the conductor. 6

7. MODEL OF EDDY CURRENT PROBE SYSTEM Fig.1 Model of eddy current probe system. 7

8. Eddy current proximity probe system can be modeled by a lumped parameter R-L-C “tank” circuit. It is designed to run at certain frequency. When oscillating current passes through a probe coil, an eddy current is generate on the surface of electrically conductive target material. This eddy current counter-affects the probe R-L-C “tank”. 8

9. The resistance & inductance vary when the physical distance changes between the probe and the metal target. Sensing the electronic circuits resistance or inductance to voltage resulting a electrical output, it is directly proportional to the physical gap. 9

10. PRINCIPLE OF DIGITAL PROXIMITY SYSTEM Majority of proximity probes system are fundamentally impedance measuring devices. At this resistance frequency impedance is a function of the characteristics of R-L-C “tank”. The relationship between impedance, inductance and resistance is Z= L/RC . Sensing electronics measure the impedance and generate output voltage. 10

11. Fig.2 Impedance change Vs gap change. 11

12. Linear relationship exist between the change in impedance & change in gap. It would be very easy for sensing electronic to directly map the gap change to the output voltage. The fact is that the impedance to gap change curve is non linear or logarithmic. 12

13. ANALOG APPROACH A pure analog system circuit may be used to exactly compensate the non linearity to linearity as shown in fig.3 Fig.3 Hardware compensation of a non linear curve. 13

14. It is not easy to perform needed compensation. The circuit components have to be properly selected. A particular set of components work for only single combination of probe tip diameter cable length, and target material. 14

15. DIGITAL APPROACH Create an algorithm in software. Each individual input is directly mapped to an output. It is easy and straight forward. Fig.4 Function diagram of a digital proximity system. 15

16. proximity system is composed of 5 key components Oscillation : The circuit of R-L-C “tank” which provide sustained oscillation at the required frequency. Peak detector : The circuit to capture the peak-to-peak value of oscillations when the gap is changing. ADC (Analog to Digital Converter) : The circuit to convert detected peak value to digital format. 16

17. MCU (Micro controller Unit) : Heart of digital proximity system. It runs algorithm. Transform digitalized non linear input data to linear digital value . DAC (Digital to Analog Converter) : It convert digital value to analog. 17

18. DIGITAL PROXIMITY SENSING FOR VIBRATION DETECTION Vibration analysis is fundamental in a predictive maintaining program. It is widely used for detecting and monitoring incipient and severe faults in machinery parts, such as bearing, shafts, coupling rotors and motors. Eddy current proximity sensing is suitable to, Varying machines to sensor distance. Demand extensive types of sensor diameter. 18

19. With proper design the oscillation frequency of eddy current sensing can be optimized to with the surface depth of any target conductive material . The nature of inductive sensing makes it even more superior to other proximity sensing technology. It basically position measuring technology. It is useful in any application requiring the measurement or monitoring of the position of a conductive target, especially in a dirty environment. 19

20. Because of high precision and fine vicinity of its measurement. It is also used to measure the dynamics of a continuously moving target such as vibrating element. With proper hardware design, software linearization scheme and compensation algorithm, a digital proximity system can detect a target in less than one mil. 20

21. ADVANTAGES OF EDDY CURRENT DIGITAL PROXIMITY SYSTEM Easy to implement as a sensor. Suitable to wide range of application. Portable and cost effective. It can be automated. 21

22. CHALLENGES OF EDDY CURRENT DIGITAL PROXIMITY SYSTEM The digital proximity system possesses from ideal benefits comparing to analog alternatives. There are still some challenges. Temperature compensation. Inter changeability. 22

23. CONCLUSION Eddy current sensing is a non contact technology capable of high-resolution measurement of position or the change of position of any conductive target. It combines complex electronic design with advanced mathematical algorithm. Integrating other cutting-edge technologies such as IC and IoT in to digital proximity sensing system. 23

24. It generates incredible potential to the evolution and applications of digital proximity sensing technology. 24

25. REFERENCE [ 1] Du, Winncy , Resistive, Capacitive, Inductive, and Magnetic Sensor Technologies, CRC Press, Boca Raton, 2014, 211-214. [2] Silva, Clarence, W., Sensor Systems: Fundamentals and Applications , CRC Press, Boca Raton, 2016, 453-455. [3] American Petroleum Institute, API Standard 670 Machinery Protection Systems (5th edition), 2014, Available: www.api.org/pubs , [Accessed March 20, 2017]. 25

26. [4] Silva, Clarence, W., Vibration: Fundamentals and Practice (2nd edition), CRC Press, Boca Raton, 2007, 485-490. [5] Texas Instruments, A revolution in sensing, Available: http :// www.ti.com/lsds/ti/sensing-products/inductive-sensing/inductive-sensing-overview.page . [Accessed March 20, 2017 ]. [6] Intel, IoT : Changing the Way We Live and Work, Available: http :// www.intel.com/content/ [Accessed March 20, 2017]. 26

27. THANK YOU… 27