Electrical Measurement and Data Acquisition System - Assignment Example

By The of the The of the School The and where it is located The ANSWERTO TASK 1. In simple terms a transducer is just a device which is used to convert a physical quantity into a corresponding electrical signal (Charles, 1990, P90). Three types are highlighted below depending on whether it is passive or active. 1. Strain Gauge transducer. Strain gauge presents a variable resistor transducer which is passive. This is basically a piezo-resistive device which is designed in such a way that it is in a position to change resistance once pressure is applied. The resulting elongation or compression causes change in the value of resistance which is determined by the measurement of force or the displacement obtained. This gauge is basically a thin metallic conductor which by applying a Stretching forces (tension) will increase the length of the wire and reduce cross-sectional area leading to increased resistance. By compressing the wire the opposed effect results (Francesco 2013, P43). Application Strain gauges are mainly applied in GMR sensors which are in the modern hard disk drives to read the heads. 2. Thermoelectric transducers This is a pure example of an active transducer. It is a device comprising of a thermocouple junction which is formed by joining two dissimilar metals at one end. By heating the junction, a small voltage basically appears between the two wires (metals). This voltage increases monotonically when the temperature is increased through what is called the see beck effect. When this couple junction is biased then the resulting effect can be used to cool a specimen. Application. It is majorly applied in cooling specimens in different areas. 3. Piezoelectric transducers It is an example of an active transducer. Basically when a quartz crystal is subjected to an external force, there results a voltage change which is generated across the entire surface. This resulting change is then measured by a corresponding value of either sound or vibration. This is called electric polarization. This effect is always linearly related to the exerted force. It’s worth noting that piezoelectric are majorly to measure very small displacement Application. Majorly applied in gas igniters, in the older version of cartridges of record players, and microscopes (Buddy 1996, P67). ANSWER TO TASK 2. 1. a) Given the VOLTS/DIV as =5 then the peak voltage is given by, VOLTS/DIV*no. of divisions = 5*1.5=7.5 v b) Peak to peak voltage =peak voltage *2 =7.5v*2=15v c) Periodic time T, =time used to make one complete cycle =TIME/DIV *no. of Divisions (Thompson & Kuckes, 1989, P87). =5ms=5/1000=0.005s*1=0.005s d) Frequency f, = 1/T=1/200=.0.005 T=1/T=1/0.005s=200Hz e) Average time=2Vp/pie=2*7.5v/pie=4.46v. 2. a) VOLTS/DIV=0.1 Peak voltage Vp= volts/div* No. of divisions=0.1*1=0.1v b) Peak to peak voltage=0.1*2=0.2v. c) Periodic time T=time to make a complete oscillation= TIME/DIV=1US=1/1000000=0.000001s d)frequency f=1/T=1/0.000001=1mHz. e) The rms value=Vp*1/root 2=0.1*0.7071=0.07071v f) The peak factor=2/2root 2=1.1107 3.a) VOLTS/DIV=50Mv.Thus peak voltage Vp=50mv=50/1000=0.05v*1=0.05v b) Peak to peak voltage=0.0582=0.01V. c) Periodic time= TIME/DIV*no. of divisions=10us=10/1000000=0.00001s d) frequency f=1/t=1/0.00001=100000Hz=100kHz. e)the mark to space ratio= 1. 4. a) VOLTS/DIV=20mv=20/1000=0.02v*1=0.02v b) Peak to peak voltage= 0.02v *2=0.04v c) Periodic time T= TIME/DIV* no. of divisions=2us=2/1000000=0.000002s*4=0.000008s d) frequency f=1/t=1/0.000008=125000hz=125kHz. e) Average value=2vp/pie=2*0.02v/pie=0.0127v f) The rms value= Vp/root2=0.02/root 2=0.0141v. g) The form factor=pie/2root 2=1.1107 ANSWER TO TASK 3. 1. a) (i) The mean of the Town route is= sum of X/no. of X =18+15+20+28+23+21.5+22+25+19+23=214.5 Mean=214.5/10=21.45 Mode for town route=23 Median for town route=put the values in order as 15, 18, 19, 20, 21.5,22,23,23,25 and 28 Thus=20+21.5/2=20.75 Standard deviation= subtract the Mean and square the result (18-21.45)^2=11.9025 (15-21.45)^2=41.6025 (20-21.45)^2=2.1025 (28-21.45)^2=42.9025 (23-21.45)^2=2.4025 (21.5.21.45)^2=0.0025 (22.21.45)^2=0.3025 (25-21.45)^2=12.6025 (19-21.45)^2=6.0025 (23-21.45)^2=2.4025 Sum of this gives =121.925 Mean of the sum = the sample variance=121.925/N-1=13.547 Square root of the sample variance gives the Standard deviation=3.6807 (II) Mean for the country route=19+21+20+22.5+19+18+23+20+19+18=199.5 Mean=199.5/10=19.95 Mode for country route=19 Median = first arrange I ascending order as below 18, 18, 19,19,19,20,20,21,22.5 and 23 19+20/2=19.5 Standard deviation= subtract the Mean and square the result (19-19.95)^2=0.9025 (21-19.95)^2=1.1025 (20-19.95)^2=0.0025 (22.5-19.95)^2=6.5025 (19-19.95)^2=0.9025 (18-19.95)^2=3.8025 (23-19.95)^2=9.3025 (20-19.95)^2=0.0025 (19-19.95)^2=0.9025 (18-19.95)^2=3.8025 Sum of this gives =27.225 Mean of the sum = the sample variance=27.225/9=3.025 Square root of the sample variance gives the Standard deviation=1.739 1. b) Which route to consider? I would consider the country route because it has a small standard deviation of 1.739 as opposed to the town route with a standard deviation of 3.6807. TASK 3 CONT’ 1. a) Periodic time t= 1/f f=50Hz=1/50=0.02s b) Frequency f=2 kHz = 2 * 1000 = 2000Hz T=1/f=1/2000=0.0005s. c) Frequency=40 kHz = 40000 Hz t=1/f=1/40,000=0.000025s 2. a) Given periodic time T=4ms=4/1000=0.004s Frequency f=1/T=1/0.004=250Hz b) Periodic time T=4us=4/1000000=0.000004s Frequency f=1/T=1/0.000004=250kHz c) Periodic time T=0.2s Frequency f= 1/T=1/0.2=5 Hz 3. a) Given periodic time T =20ms =20/1000=0.02s Frequency f=1/T=1/0.02=50Hz b)the rms value is Vp*1/root 3= 200v* 1/root 3=115.47v c) 0.5* Vp=0.5*200=100v 4. a)a sine wave, periodic time T=16ms=16/1000=0.016s Frequency f=1/0.016=62.5Hz (Lincoln, 2003, P73) b) rms voltage =Vp=10v c) Average value =Vp=10v 5. a) Frequency 1 kHz = 1000 Hz Periodic time T=1/f=1/1000=0.001s b) rms value =0.7071*300=212.13v c) Average value is =0.637*300=191.1v 6.(i) a)frequency of waveform = 1/T= 1/10/1000=1/0.01s=100Hz b) rms value is =vp/root 3=5Ma=5/1000=0.005A*1/root 3=0.0028A c) Average value =0.5*0.005A=0.0025A (ii) a) Frequency of waveform is =1/T=1/4ms/1000=1/0.004=250Hz b) rms of a square wave is =vp=20v c) Average value of a square wave=vp=20v. ANSWER TO TASK 4. 1. Mean time between failure commonly abbreviated as MTBF is a measure of how a given hardware or component is reliable. MTBF for many hardware components ranges between thousands up to ten of thousands of hours between failures. In an electronic component such as a hard disc drive could have a mean time between failures of about 300,000 hours. 2. Mean time to failure which is abbreviated as MTTF is given as the average time during which a hardware or component will function before it fails. It is the mean life time of the component. Though the MTTF is very important, it cannot be relied mostly especially when we use a censored data. This is because the average does not provide the best measure of the center 3. Examples of three electrical passive transducers;- Optoelectronic transducer Hall Effect transducers. Variable resistance transducers. 4. Three examples of mechanical transducers:- Piezoelectric transducers Electromagnetic transducers Moving Coil transducer 5. Damping is an amplitude decrease of an oscillation resulting energy that is being drained from the system so as to overcome either frictional or other resistive force. 6. A transfer function is a mathematical function which relates an output or response of a system such as a filter circuit to the systems input or stimulus. The importance of a transfer function. Through analysis of the transfer function one is in a position to determine the state of the system i.e. to know whether the system is stable or not. 7. A dynamic range is a ratio of the softest sound to the loudest sound in an electrical component. A dynamic range is usually measured in decibels which are abbreviated as dB Units. When one intends to indicate the maximum output signal of a component to the rate of systems noise floor he uses the dynamic range. For example the dynamic range of a human being is always used as 120dB. 8. What is a form factor? A form factor basically is compensating mathematical factor which is used when dealing with irregular shapes of objects. It is a ratio between the volume of the irregular shape and that of a regular shape with the same breath and height. For instance, the physical size and the shape of a piece of a computer hard ware. Given an idea and a continuous wave function over time T, then the RMS can be found in integral form as;- Where the rectified average as shown above becomes the absolute value of the integral mean. 9. The peak factor also known as the crest factor is the wave forms peak amplitude divided by the root mean square or RMS value of the concerned waveform. 10. Twisted pair cable Co-axial cable Optical fibre 1.Transmission of signals takes place in the electrial form over the metallic conducting wires 1.Transmission of signals takes place in electrical form over the inner conductor of the cable 1. signal transmission takes place in an optical form over a glass fibre 2.In this medium the noise immunity is low 2. coaxial having higher noise immunity than twisted pair cable. 2.optical fibre has highest noise immunity as the light rays are unaffected by the electrical noise. 3. Twisted pair cable can be affected due to external magnetic field 3.coaxial cable is less affected due to external magnetic field. 3.Not affected by the external magnetic field. 4. Cheapest medium 4. Moderate expensive 4. Expensive 5.Low Bandwidth 5.Moderately high bandwidth 5.Very high bandwidth 6. Attenuationis very high 6.Attenuation is low 6.Attenuation is very 7.Installation is easy 7.installation is fairly easy 7.installation is difficult 11. In measurement and recording of data, error is that difference which exists between the measured value of a quantity and the true value. In statistics it is always wrong to view error as a mistake since variations will always exist and are inherent during the measurement process 12. In electronic test equipment there exists the D/A and A/D functions. A D/A convertor converts a digital data which is in binary form to an analog form or signal such as current, voltage or just mere electrical charge. On the other side, An A/D convertor converts data in analog form back to the digital form. The reverse of the D/A convertor. It is worth noting that digital data can be stored, transmitted or even manipulated without degeneration as opposed to analog data which will be subject to data degradation. Despite this draw back, D/C convertors are inevitable since one has to the digital signal to analog so as to drive things such as the motors or even an earphone. 13. A digital voltmeter (Millard, 2006, P56) 14. Firstly, connect the voltmeter to the output terminals of the amplifier. The voltmeter should be set to AC voltage. Secondly, turn up the head unit’s volume as you watch the voltage reading rise.at this time the meter will be gauging the power intensity that is going to the subwoofers, Wait until when the voltage reading reaches the peak when at this the power is maximum value.. At this time, the voltage obtained ids the peak voltage rating of the amplifier. To test the functionality of the system, use a calculator to multiply the peak values by itself. By dividing the product with the subwoofers ohm load. By doing this calculations, one can determine the functionality of the system. Power produced by the amplifier Peak Power / 2 = RMS Power produced by amplifier I.e. (AC Voltage x AC Voltage) / Impedance of the Subwoofer = Peak ANSWER TO TASK 6.  Data acquisition systems are products or just processes that are used to collect information for documentation purposes or for analysis..  Laboratory Data Acquisition system (DAQ) These are products used in the laboratory for data collection for documentation or analysis. For example a technician can log the temperature of an on a piece of paper is said to do data acquisition. Portable Data acquisition system These are products used to collect data for documentation or analysis and are based on a portable pc. Comparison of the two types of systems. Laboratory Data Acquisition system (DAQ Portable Data acquisition system Often rack mounted (19-inch racks • Stand-alone units, like data loggers, that do not need a PC connection (e.g. a flight data recorder) Permanent location • PC-based (connected to a PC) Can be a large and heavy installation Small and light Data acquisition block diagram. Transducers These sense the physical phenomena and translate it into an electric signal. Physical phenomena could be: Temperature Pressure Light Force Displacement and level etc. Actuators. An actuator is a device which will activate the process control system by the use of electrical, pneumatic or hydraulic power. For instance we have a valve actuator which will control the fluid flow rate. Signal conditioning This is done by a circuit embedded in the system. This improves the quality of the signal which is generated by transducers after which they get converted into digital signals. This is done by the PC’s Data acquisition hardware. Signal conditioning could be through signal scaling, linearization excitation etc (Leo 1994, P45). Data acquisition Data acquisition and the control hardware performs the functions such as analog input, analog output digital input digital output and the basic counter functions For instance the input signal function may be as below. During this conversion, analog voltages or current values are changed into digital information. This process enables the computer to be in a position to process and store the signals. Analog outputs These converters operate in the opposed of D/A convertors. Here the digital information is converted into analog voltage or current and by so doing the computer is in a position to control real world situations. It is worth noting that this analog output signal may be in direct proportion with the process control equipment. This results to what is called the closed loop system with PID control Wave forms can also be generated from the analog output and thus making the device function like a function generator. Data acquisition software. This is usually the most important factor in an endeavor to obtain high performing and reliable system. This software transforms the both the PC and the DAQ hardware being used into perfect system which can do the analysis and display. The software comes in different alternatives such as the programmable software and the data acquisition software packages (Simon, 2002, P78). Programmable software enables programming languages such as the c+,c++Visual basic etc. Conclusion on which type is best? By analyzing the laboratory data acquisition systems and the portable data acquisition systems it would be inevitable to conclude that the pc based data acquisition systems are the best. This is because of the transfer capabilities of the PC (computer) the portability and the medium size which make them a better choice (Simon 2001, P34). Reference Simon McBeath (2002). Competition Car Data Logging: A Practical Handbook. J. H. Haynes & Co. ISBN 1-85960-653-9. Simon S. Young (2001). Computerized Data Acquisition and Analysis for the Life Sciences. Cambridge University Press. ISBN 0-521-56570-7. W. R. Leo (1994). Techniques for Nuclear and Particle Physics Experiments. Springer. ISBN 3-540-57280-5. Charles D. Spencer (1990). Digital Design for Computer Data Acquisition. Cambridge University Press. ISBN 0-521-37199-6. B.G. Thompson & A. F. Kuckes (1989). IBM-PC in the laboratory. Cambridge University Press. ISBN 0-521-32199-9. Buddy Fey (1996). Data Power: Using Racecar Data Acquisition. Towery Pub. ISBN 1-881096-01-7. Francesco Fornetti (2013). Instrumentation Control, Data Acquisition and Processing with MATLAB. Explore RF Ltd. ISBN 978-0957663503.  Lincoln D. Jones (2003). Electrical Engineering License Review (8th ed.). Dearborn Trade Publishing. p. 6‑15. ISBN 978-0-7931-8529-0. Millard F. Beatty (2006). Principles of engineering mechanics. Birkhäuser. p. 167. ISBN 978-0-387-23704-6.  Billings S.A. "Nonlinear System Identification: NARMAX Methods in the Time, Frequency, and Spatio-Temporal Domains". Wiley, 2013 Read More