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Induction motor response to periodical voltagefluctuations

Jose Baptista, Jose Goncalves, Salviano Soares, Antonio Valente, Raul Morais, Jose Bulas-Cruz,Manuel J.C.S. Reis

Abstract—The main aim of this paper is to analyze thebehavior of the three-phase squirrel cage induction motor underdifferent voltage fluctuation levels. To achieve this goal severalsimulations were performed using the EMTP/ATP tool. Here wepresent how mechanical torque, speed and efficiency parametersvaried with different levels of voltage fluctuation and modelingfrequencies. As it was expected, the induction motor is sensi-tive to voltage fluctuations within certain amplitude levels andfrequencies. Also, the speed is more affected by low frequenciesand high amplitudes of voltage fluctuations, while the torque andefficiency are more affected by middle and high frequencies andamplitudes.

I. INTRODUCTION

Presently, electricity is one of the fundamental pillars ofmodern society and widely used by the industrial and tertiarysectors. Due to its own nature, it cannot easily be storedin large quantities, so its production must be adjusted toconsumption at all times. The integration of the production,transmission and distribution systems of the electric grid istherefore decisive to ensure both security of supply (continuityof service) and a number of technical specifications thatconstitute what may be named as Power Quality (PQ).

Electrical PQ is a crucial competitive and developing factorto all economic areas. The economic losses resulting frompower quality problems can be significant, particularly inindustry, so this is a matter of great concern.

The induction motor is probably the mostly widely useddevice in industrial environments to perform a set of taskswhere mechanical power is needed, due to its rugged configu-ration and versatility. Thus, it is fundamental to know how thistype of machine behaves when submitted to the most commondisturbances. It is therefore necessary to define criteria forassessing the power quality, relating them to the equipment’susage disturbance admissibility limits, in our case the three-phase induction motor.

A great number of standards on electrical power qualityhave been published in recent years, most of them proposedby European and International organizations. The two mostcommon power quality standards in use today are the IEC

J. Baptista, J. Goncalves, S. Soares, A. Valente, R. Morais, J. Bulas-Cruzand M.J.C.S. Reis are with the University of Tras-os-Montes e Alto Douro(UTAD), School of Sciences and Technology, Engineering Department, 5001-801 Vila Real, Portugal. E-mail: baptista@utad.pt, jagoncalves@gmail.com,{salblues, avalente, rmorais, jcruz, mcabral}@utad.pt.

S. Soares, A. Valente, and M.J.C.S. Reis are with Instituto de EngenhariaElectronica e Telematica de Aveiro (IEETA).

R. Morais is with Centre for the Research and Technology of Agro-Environment and Biological Sciences (CITAB).

J. Bulas-Cruz is with Research Center in Sports, Health Sciences andHuman Development (CIDESD)

61000-4-30 [1] and the EN 50160 [2]. The IEC 61000-4standard provides measurement methods, describes measure-ment formulas, sets accuracy levels and defines aggregationperiods. The main motivation for this standard is to providecommon requirements for measurement devices to ensure thatanalyzers from different manufacturers give the same results.The EN 50160 standard provides recommended levels fordifferent power quality parameters to be observed in lowvoltage electrical networks. In [3] the authors present a setof practical case studies related to the application of thesestandards.

Disturbance effects can be divided into short-term effects(incorrect behaviour of a device, or set of devices) and long-term effects, such as overheating, isolation deterioration andlifetime reduction. Most of the common disturbances haveboth short-term and long-term effects.

The response of induction motors to regular voltage fluc-tuations in the flicker frequency range has been investigatedby [4], where results of the speed and current variation arepresented. Reference [5] also addresses this problem, empha-sizing the effects of other type of charges (three-phase PWM-VSI frequency converter, single-phase linear source and single-phase switched source).

This paper aims at determining the response of an induc-tion motor, particularly in terms of speed, torque, heating,mechanical vibrations and efficiency, under different voltagefluctuation conditions.

II. THE SIMULATION TOOL

The number of tools suitable for transient analysis is in-creasing during the last few years. Among these tools wecan mention the well-known ElectroMagnetic Transients Pro-gram (EMTP) and its variants Alternative Transients Program(ATP), Electromagnetic Time Domain Transient (PSCAD-EMTDC), MATLAB-SIMULINK, etc. Computer tools to helpprofessors and students alike in the teaching-learning processhave become very popular [6].

In this work we have used the EMTP/ATP program [7],with its input graphical interface ATPDraw [8], allowing theimplementation of the model and the application of powerquality disturbances and subsequent analysis of the effects.

ATP is a universal system for digital simulation of transientphenomena of electromagnetic and electromechanical nature.With this tool, complex networks and control systems ofarbitrary structure can be simulated. ATP has extensive model-ing capabilities and additional important features, besides thecomputation of transients. It has been continuously developedthrough international contributions over the past 20 years [6].

XIX International Conference on Electrical Machines - ICEM 2010, Rome

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With ATP the user has the possibility to use the MODELSprograming language to represent elements, controlling asystem represented by an EMTP code, and also providing agreater flexibility for performing numerical and logical manip-ulations of variables. MODELS syntax allows the representa-tion of a system to either reflect its physical implementation,using a block approach, or describe its operation, using a directdescription of its functional structure [9].

III. VOLTAGE FLUCTUATIONS AND THE INDUCTION MOTOR

Among the various disturbances affecting power supply,voltage fluctuations are one of those occurring most frequentlyand the consequences to the supply system and loads shouldbe rigorously studied in order to avoid the adverse effects onequipment and on the power system. According to the EN50160 [2] standard, voltage fluctuations are variations in theRMS value or the peak value with an amplitude of less than±10% of the nominal voltage. They are characterized by thefrequency of variation (fm), up to 30Hz, and magnitude (∆V

V ).Usually, voltage fluctuations are associated with the Flickereffect and may be the cause or the effect of fluctuations inthe energy system transmission and its admissibility limitsare established by the standards IEC 610000-3-3 [10] andIEC 610000-3-5 [11]. Among the devices that cause mostof these disturbances are loads that have fast variations inits operation, which induce voltage drops in the network;arc furnaces, welding machines, induction motors, large loadsswitching, discharge lamps ignition and household applianceswith automatic time and temperature controls.

Voltage

Time

f1

Fig. 1. Voltage fluctuation with a periodical sinusoidal modulation.

There are different types of voltage fluctuations and theycan be classified into different categories: periodical voltageoscillations with constat amplitude; irregular amplitude stepsand continuous random fluctuations. The goal of this paperis to studied the induction motor behaviour under periodicalvoltage fluctuations (sinusoidal envelope) with constant am-plitude, figure 1.

Typically induction motors are designed to tolerate a smalllevel of voltage fluctuations. However, certain fluctuationlevels can cause serious problems to the motor operation,which in turn may cause protection systems triggering, andultimately leading to production loss.

Induction motors are AC asynchronous machines with inter-nally induced rotating magnetic fields, where his magnitude isproportional to the voltage amplitude. Hence, in the presenceof supply voltage fluctuations, the total rotating magnetic field

becomes oscillating. As in the case of voltage unbalance, theresult is the possibility of speed and torque pulsations andincreased motor noise. Another parameter also greatly affectedis the motor efficiency, due to the large variation found forthe stator and rotor losses [12]. The results obtained in thesimulations prove what was said previously.

IV. MODELLING

The problem of estimating the equivalent circuit parame-ters of induction motors has been studied in several papers[13][14][15][16]. Generally, induction motor parameter esti-mation methods can be classified into five different categories,depending on what data is available, and what the data isused for: parameter calculation from motor construction data;parameter estimation based on steady-state motor models;frequency-domain parameter estimation; time-domain param-eter estimation and real-time parameter estimation [13]. Oneof the most widely used methods to calculate the motor’sequivalent circuit is through manufacturer parameters data, andis very well described in [14].

In order to obtained the electrical parameters to completethe steady-state equivalent circuit for the induction motor, alaboratory tests were performed, acording IEEE standard 112,[17]. These results were used to find the equivalent circuitdepicted in figure 2.

In order to accomplish this work, a model of an three-phaseinduction motor with a mechanical load was created using theATPDraw interface software for the ATP/EMTP, by adaptingthe UM3 universal machine model, shown in figure 3. Thedeveloped circuit has two MODELS blocks: one is responsiblefor injecting different types of voltage fluctuations in the motorsupply, and the other is responsible to preform all the neededcalculations to obtain the motor efficiency.

The induction motor under study has the following charac-teristics: 380V of nominal voltage; 1.1kW of rated power;50Hz of rated frequency; 2820rpm of rated speed; and 2poles, the motor inertia is 0.008Kg ·m2. To all simulationswas considered a constant torque load with 3.72Nm

Iabs

7,8 j4,57 j6,86

5,778s

Io

Uf

W W W

Wj146,3 W3,27 kW

Fig. 2. Steady-state equivalent circuit for the induction motor used.

Figure 4 shows the induction motor torque-speed character-istic, torque and efficiency curves when no disturbances arepresent, at the rated conditions and connected to a nominalmechanical load. As expected, it can be seen that in theabsence of supply disturbances the induction motor responseis perfectly stable.

V. SIMULATIONS RESULTS

This section is use to present some results, selected from awide range of simulated parameters. The model implemented

3

IM MODEL

default

Auto Adjust

I

V

M

I

MO

DE

L

rend.s

up

Iw

LoadTorque

Frictioncoefficient

Motorinertia

Electrical network

Mechanical load

Fig. 3. ATPDraw induction motor and mechanical load simulation circuit.

0 500 1000 1500 2000 2500 3000

0

2

4

6

8

10

12

Speed [rpm]

To

rqu

e [

Nm

]

Tn

Nn

(a)

0,0 0,4 0,8 1,2 1,6 2,0

0,0

2,2

4,4

6,6

8,8

11,0

Time [s]

To

rqu

e [

Nm

]

(b)

0,0 0,4 0,8 1,2 1,6 2,0

0

20

40

60

80

100

Time [s]

Effic

ien

cy [

%]

(c)

Fig. 4. Motor rated characteristic (no disturbances are present, at the ratedconditions and connected to a nominal mechanical load). (a) Speed-torquecharacteristic and nominal operating point, (b) torque, (c) efficiency

in figure 3 allowed to simulate not only the input parameters(voltage, current and power), but also several motor outputparameters (speed, torque, power, machine losses and effi-ciency). Here, we will present and analyze the induction motorbehavior regarding to speed, torque and efficiency.

In order to estimate the effect of the voltage fluctuationson the induction motor behavior, four different scenarios werecreated, presented in table I. On each scenario a constantnominal mechanical load was considered, disturbances wereintroduced at t = 0s and the motor was considered stoppedfor t = 0s. Figure 5 shows an example of the voltagessupply and line currents for case 2 with fm = 10Hz. In thepresence of a 20% voltage fluctuation the model needs someadjustments. Particularly, the magnetizing parameters in theequivalent circuit need specific corrections. Nonetheless wepresent the results given by our method under these conditions.

The selected results are presented in the following subsec-tions.

TABLE ICASE STUDIES

Case ∆VV

% fm(Hz)1 2 1 10 252 5 1 10 253 10 1 10 254 20 1 10 25

0,0 0,2 0,4 0,6 0,8 1,0

-400

-300

-200

-100

0

100

200

300

400

Time [s]

Vo

lta

ge

[V

]

(a)

0,0 0,2 0,4 0,6 0,8 1,0-20

-15

-10

-5

0

5

10

15

20

Time [s]

Curr

ent [A

]

(b)

Fig. 5. Motor supply for case 2 with fm = 10Hz (a) Voltage, (b) Current

4

A. Speed responseWith these simulations we want to study how the motor

speed reacts to voltage fluctuations for the four differentscenarios. The first conclusion is that voltage fluctuations arereflected in speed oscillations with the same signal modulationfrequency. This same conclusion can be drawn to the torqueand efficiency parameters.

Figure 6 illustrates the motor speed behavior. As we cansee, the most severe speed oscillation occurs for the lowerfrequency modulation (fm = 1Hz), and it gets worse withincreasing amplitude of the fluctuations; however, the averagespeed is the same for all cases. For fm = 10Hz the speedoscillations are very small for all cases. Also note that forfm = 25Hz, although the speed fluctuation is relatively small,there is a slight decrease in the average speed, with increasingamplitude of the voltage fluctuations.

0,60 0,98 1,36 1,74 2,12 2,502700

2750

2800

2850

2900

2950

3000

Time [s]

Speed

[rp

m]

Case 2

Case 3

Case 1

Case 4

(a)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

2700

2750

2800

2850

2900

2950

3000

Time [s]

Speed [rp

m]

Case 2

Case 3

Case 1

Case 4

(b)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

2700

2750

2800

2850

2900

2950

3000

Time [s]

Speed [rp

m]

Case 2

Case 3

Case 1

Case 4

(c)

Fig. 6. Voltage fluctuations effects on motor speed (a) fm = 1Hz, (b)fm = 10Hz, (c) fm = 25Hz

Figure 7 summarizes the speed fluctuations. The biggest

variation, of 2.87%, occurs for case 4, fm = 1Hz.

Speed v

ariation [%

]

0,5

0

1 10 25

1

1,5

2

2,5

3

3,5

f [Hz]m

Case 2

Case 3

Case 1

Case 4

Fig. 7. Comparison of rotor speed fluctuation for the four case studies.

B. Torque response

The torque is also very affected by voltage fluctuations. Fig-ure 8 illustrates the motor torque behavior for all cases. As wecan see in this figure, the most severe torque oscillation occursfor the higher frequency (fm = 25Hz), and it gets worse withincreasing amplitude of the fluctuations. For fm = 1Hz andfm = 10Hz the torque oscillations are very small for the twofirst cases. Also note that, the average torque is the same forall cases, and that the oscillations increase with frequency.

Figure 9 summarizes torque fluctuations. The biggest vari-ation is of about 146.7%, occurring for case 4 at fm = 25Hz.

C. Efficiency response

The motor’s efficiency is of paramount importance, becauseelectrical motors are major consumers of electricity in themodern industrial society; for example, in the European Unionindustrial sector they consume approximately 69% of theneeded electricity, while this values drops to approximately36% in the tertiary sector, [18], [19].

Figure 10 illustrates the motor efficiency for all studiedcases. As we can see in this figure, the most severe efficiencyoscillation occurs for the higher frequency (fm = 25Hz), andit gets worse with increasing amplitude fluctuations. For thetwo first cases, and for fm = 1Hz and fm = 10Hz, theefficiency oscillations are very small (below 5%). It is alsoto note that the average efficiency is of about 84%, being thesame for all cases, and the oscillations increase with frequency.

Figure 11 summarizes torque fluctuations. The biggest vari-ation, of about 34.6%, occurs for case 4, fm = 25Hz.

VI. CONCLUSION

The increasing level of power quality disturbances can haveconsiderable effects on the behavior of electric machines, theirloads and lifetime of both, with the respective economic conse-quences. Incorrect behavior of some equipments and increasedlosses are also consequences of poor power quality. Voltagefluctuations is a type of disturbance that occurs regularly inpower systems and its consequences in the loads can be veryadverse.

The response of induction motors to periodical voltagefluctuations has been studied. Although pure sinusoidal voltage

5

0,60 0,98 1,36 1,74 2,12 2,50

2,0

2,5

3,0

3,5

4,0

4,5

5,0

5,5

6,0

Time [s]

Torq

ue

[N

m]

Case 2

Case 3

Case 1

Case 4

(a)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

2,0

2,5

3,0

3,5

4,0

4,5

5,0

5,5

6,0

Time [s]

Torq

ue [N

m]

Case 2

Case 3

Case 1

Case 4

(b)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

0

2

4

6

8

10

Time [s]

Torq

ue [N

m]

Case 2

Case 3

Case 1

Case 4

(c)

Fig. 8. Voltage fluctuations effects on motor torque (a) fm = 1Hz, (b)fm = 10Hz, (c) fm = 25Hz

160

f [Hz]

Torq

ue v

ariation [%

]

m

140

120

100

80

60

40

20

0

1 10 25

Case 2

Case 3

Case 1

Case 4

Fig. 9. Comparison of torque fluctuation for the four case studies.

fluctuations do not represent practical situations, they werethe starting point to investigate three-phase induction mo-tor performance dependence on a particular amplitude andfrequency. The studies carried out show that the inductionmotor, although robust, is sensitive to voltage fluctuations

0,60 0,98 1,36 1,74 2,12 2,50

70

75

80

85

90

95

100

Case 2

Case 3

Case 1

Time [s]

Effic

iency [%

]

Case 4

(a)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

70

75

80

85

90

95

100

Time [s]

Effic

iency [%

]

Case 2

Case 3

Case 1

Case 4

(b)

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00

70

75

80

85

90

95

100

Time [s]

Effic

iency [%

]

Case 2 Case 3Case 1 Case 4

(c)

Fig. 10. Voltage fluctuations effects on motor efficiency (a) fm = 1Hz, (b)fm = 10Hz, (c) fm = 25Hz

40

f [Hz]

Effic

iency v

ariation [%

]

m

35

30

25

20

15

10

5

0

1 10 25

Case 2

Case 3

Case 1

Case 4

Fig. 11. Comparison of efficiency fluctuation for the four case studies.

within certain amplitude levels and frequencies. We have alsoseen that speed is more affected by low frequencies andhigh amplitudes of voltage fluctuations, while the torque andefficiency are more affected for middle and high frequencies

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and amplitudes.The developed model provided an adequate basis for the

study of other disturbances, applied to a standard mechanicalload. Future enhancements of the model should be able toaccommodate more detailed, complex mechanical loads, aswell as a more accurate measurement system. In a near futurewe want to do further experimentations in order to validate thesimulation results presented here, especially the ones relatedto the 20% voltage fluctuations.

ACKNOWLEDGMENT

The authors would like to thank Professor Hans KristianHoidalen from Norwegian University of Science and Tech-nology and Nicola Chiesa from SINTEF Energy Research,for their help in the implementation of ATPDraw MODELSblocks.

REFERENCES

[1] IEC 61000-4-30, “Testing and measurement techniques — Power Qual-ity measurement methods,” International Electrotechnical Commision,pp. 81–79, 2003.

[2] “NP EN 50160: Voltage characteristics of electricity supplied by publicdistribution systems,” CENELEC, 1995.

[3] A. Broshi, “Monitoring Power Quality Beyond EN 50160 and IEC61000-4-30,” in 9th International Conference in Electrical Power Qual-ity and Utilisation, Barcelona, Spain, 9-11 October 2007.

[4] S. Tennakoon, S. Perera, and D. Robinson, “Flicker attenuation—Part I: Response of three-phase induction motors to regular voltagefluctuations,” IEEE Transactions on Power Delivery, vol. 23, no. 2, pp.1207–1214, April 2008.

[5] C. A. G. Medeiros and J. C. de Oliveira, “Effects of voltage fluctuationassociated to flicker limits on equipments performance,” in 10th Inter-national Conference in Harmonics and Quality of Power, vol. 1, Rio deJaneiro, Brasil, 6-9 Oct. 2002, pp. 347–352.

[6] F. Jurado, N. Acero, J. Carpio, and M. Castro, “Using various computertools in electrical transients studies,” in 30th Annual Frontiers inEducation - Vol 2, Kansas City, October 18 - 21, 2000.

[7] H. W. Dommel, EMTP Theory Book. BPA, 1986.[8] L. Prikler and H. K. Hoidalen, ATPDraw for Windows User’s Manual,

Version 1.0. BPA, November 1998.[9] J. A. Martinez, B. Johnson, and C. Grande-Moran, “Educational use

of EMTP MODELS for the study of rotating machine transients,” IEEETransactions on Power Systems, vol. 8, no. 4, pp. 1392–1399, November1993.

[10] “IEC 61000-3-3: Electromagnetic Compatibility (EMC), Part 3: Limits-Section 3: Limitation of voltage fluctuations and flicker in low-voltagesupply systems for equipment with rated current ≤ 16A.” InternationalElectrotechnical Commision, 1994.

[11] “IEC 61000-3-5: Electromagnetic Compatibility (EMC), Part 3: Limits-Section 5: Limitation of voltage fluctuations and flicker in low-voltagesupply systems for equipment with rated current > 16A,” InternationalElectrotechnical Commision, 1995.

[12] A. von Jouanne and B. Banerjee, “Assessment of voltage unbalance,”IEEE Trans. on Power Delivery, vol. 16, no. 4, pp. 782, 790, October2001.

[13] D. Lindenmeyera, H. Dommel, A. Moshref, and P. Kundur, “An induc-tion motor parameter estimation method,” Electrical Power and EnergySystems, vol. 23, no. 4, pp. 251–262, May 2001.

[14] G. J. Rogers and D. Shirmohammadi, “Induction machine modeling forelectromagnetic transient program,” IEEE Trans. Energy Convers, vol. 2,no. 4, pp. 622–628, December 1987.

[15] J. Pedra, “On the determination of induction motor parameters frommanufacturer data for electromagnetic transient programs,” IEEE Trans-actions on Power Systems, vol. 23, no. 4, pp. 1709–1718, November2008.

[16] J. A. Martinez, B. Johnson, and C. Grande-Moran, “Parameter deter-mination for modeling system transients–Part IV: Rotating machines,”IEEE Transactions on Power Delivery, vol. 20, no. 3, pp. 2063–2072,July 2005.

[17] “IEEE Standard test procedure for polyphase induction motors andgenerators,” Institute of Electrical and Electronics Engineers, Inc, 1996.

[18] H. Falkner, “Promoting High Efficiency Motors in Europe. The role ofthe copper Industry,” in ETSU. European Copper Institute, Nov. 2000.

[19] S. Corino, E. Romero, and L. Mantilla, “How the efficiency of inductionmotor is measured?” in International Conference on Renewable Energyand Power Quality, Santander, Spain, 11-13 Mar. 2008.

BIOGRAPHIES

Jose Baptista graduated in Electrical Engineering from the University ofTras-os-Montes e Alto Douro (UTAD), Portugal in 1991. He obtained theM.Sc. degree in Power Electronics in 1997 from UTAD and the Ph.D. degreein Electrical Engineering in 2007 from UTAD. Presently, he is an AssistantProfessor in the Department of Electrical Engineering, UTAD. He is also aresearcher in power quality, electrical machines and renewables. His maininterest areas are power quality, electrical machines and renewables.Jose Goncalves graduated in Electrical Engineering from the PolytechnicInstitute of Leiria (IPL), Portugal in 2007. He obtained the M.Sc. degree inElectrical Machines in 2008 at UTAD University. Presently, he is an ElectricalEngineer working for the local government in Portugal. His main interest areasare power quality, electrical machines and sustainable energy development.Salviano F. S. P. Soares graduated in Electrical Engineering from UTAD,Portugal in 1991. He obtained the M.Sc. degree in Electronics and Telecom-munications in 1995 from University of Aveiro (UA), Portugal, and thePh.D. degree in Electrical Engineering in 2005 from UA. Presently. He isan Assistant Professor at the Department of Electrical Engineering, UTAD,and also a researcher at the Institute of Electronics and Telematics Engineeringof Aveiro (IEETA). His main interest area is Digital Signal Processing.Antonio Valente graduated in Electrical Engineering from UTAD, Portugalin 1994. He obtained the MSc degree in Industrial Electronics in 1999 fromthe University of Minho, Portugal and the PhD degree in Microelectronics in2004 from UTAD. Presently, he is an Assistant Professor in the EngineeringDepartment, UTAD, were he is the vice-director of the Bologna’s MSccurriculum and the director of the Bologna’s first cycle curriculum. He is also aresearcher at IEETA and he is involved in the research of silicon microsensorsfor agriculture.Raul Morais dos Santos graduated in Electrical Engineering from UTAD,Portugal in 1993. He obtained the M.Sc. degree in Industrial Electronics in1998 from the University of Minho, Portugal and the Ph.D. degree in Micro-electronics in 2004 from the UTAD. Presently, he is an Assistant Professor inthe Department of Electrical Engineering, UTAD. He is also a researcher in theSignal Processing and Biotelemetry group and the Center for the Research andTechnology of Agro-Environment and Biological Sciences (CITAB), and heis involved in the development of instrumentation solutions, energy harvestingtechnologies and mixed-signal sensing interfaces for agricultural applications.He is also leading the CITAB effort of implementing an agricultural remotesensing network in the Demarcated Region of Douro, a UNESCO HeritageSite.Jose A.M. Bulas-Cruz graduated in Electrical Engineering from the Univer-sity of Porto (FEUP), Portugal, in 1978. He obtained the PhD degree fromthe University of Bristol, in the UK, in 1995. He served as Vice-Rector forInnovation and Technology (UTAD) from 2005 to 2008. Presently, he is FullProfessor of Computer Vision in the Engineering Department, UTAD, servingas Head of Department. He is also a researcher at the CIDESD researchcentre, involved in the research of Functional and Morphological Assessmentin Animal (rats) Models, using Computer Vision. During the years of 1999 to2008 he was co-responsible for eight research projects related to InformationTechnologies and Internet dissemination and use as a learning/teaching toolin the Tras-os-Montes e Alto Douro region.M.J.C.S. Reis received the PhD degree in Electrical Engineering and the MScdegree in Electronics and Telecommunications from the University of Aveiro,Portugal. Currently he is Associate Professor (Agregado) in the EngineeringDepartment, UTAD, Portugal. He is also a researcher at IEETA. He histhe director of the Signal Processing and Biotelemetry research group ofUTAD. His research interests are in the area of signal processing, and includemodeling and approximation, and problems such as sampling, interpolation,and signal reconstruction. Since 2000 he was co-responsible for eight researchprojects related to Information Technologies and Internet dissemination anduse as a learning/teaching tool all over the Tras-os-Montes e Alto Douroregion.