ee20l-exp1
TRANSCRIPT
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Experiment 1: Familiarization with Electrical Measuring
InstrumentsIan Camus#1, Shizhao Chen#2, Ma. Marvilette P. Jequinto#3, Jerome Lopena#4
School of Mechanical and Manufacturing Engineering, Mapa Institute of Technology
Muralla Street, Intramuros, Manila, Philippines
1
Abstract Before going to complicated processes, the
basics on Electrical Circuits must be understood first.
In this experiment, the functions of the basic electric
circuit training kit (EEC471-2 and EEC470) werefamiliarized and the proper connection was learned. In
the first part of the experiment, a basic electric circuit
was done. The Analog D.C. ammeter was used to
measure the current flowing through the circuit while
a digital multimeter was used to determine the
resistance and the voltage. Ten different values of
resistors were used and resulted to different values of
current and power. And in the second part of this
experiment, Tina Pro was used to design a model of the
basic electric circuit we had. The necessary data were
input and results were automatically shown. This
experiment establishes our skill in using the electricalmeasuring devices correctly.
Keywords ammeter, multimeter, resistor, current,
voltage
I. INTRODUCTION
There are specific measuring instruments used instudying electric circuits. Each instrument has its own
function and procedures on how to operate.
In 1886, Edward Weston produced a practical precision,direct reading, portable instrument to accurately measureelectric current, a device which became the basis for the
voltmeter, ammeter and watt meter.
In the early 1880s, Jacques DArsonval and MarcelDeprez invented the first kind of ammeter- the DArsonvalgalvanometer. It is a versatile analog instrument used in
detecting and in measuring a small amount of current in the
circuit (Hortinela IV 2011). So far, there are four kinds ofammeter - the DArsonval galvanometer which measuredirect current of from 0.1 to 2.0%; the electrodynamic
ammeter which uses a moving coil rotating in the fieldproduced by a fixed coil and measure alternating currentwith accuracies of from 0.1 to 0.25%; the thermal ammeterwherein the measure current heats a thermoconverter(thermocouple), and measure alternating current of from
0.5 to 3%; and the digital ammeter which uses a circuitsuch as the dual slope integrator to convert a measuredanalog (continuous) current to its digital equivalent andhave accuracies better than 0.1%.
Along with the ammeter is the voltmeter which was alsoinvented by DArsonval. Voltmeter is a device that
measures voltages (electric potential difference betweentwo points) of either direct or alternating current.
Technically, voltmeter is an ammeter, but using Ohmslaw, the amperes could be scaled up to voltages. There arefour distinct types of voltmeter - the electromechanical
wherein a mechanical interaction generates a mechanicaltorque proportional to the voltage or the squared voltage to
be measured (Halit 2013); the thermal type instrumentwherein the measurement is based on the thermal effectsof a current flowing into a conductor and their reading is
proportional to the squared input voltage; the electronicinstruments which is based on purely electronic circuits,
and attain the required measurement by processing theinput signal by means of electronic semiconductordevices; and the oscilloscope or the vacuum-tube
instrument which is basically a voltmeter and the maincharacteristic is to allow a graphic representation on a
cathode ray-tube (CRT) of the input signal.
Nowadays, digital multimeters are used in measuring
ohms, amperes, voltages and in some, the capacitance.
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Digital multimeters have a liquid-crystal-display (LCD)that gives a straightforward decimal read out.
Electric circuits could now be designed through the
computer using the software Tina Pro. TINA DesignSuite is a powerful yet affordable circuit simulation andPCB design software package for analyzing, designing,
and real time testing of analog, digital, VHDL, MCU, andmixed electronic circuits and their PCB layouts. This is
used to design and run a virtual electric circuit. Resultsfrom the change of components and data will beautomatically shown.
II. MATERIALS AND METHODS
The materials used in the experiment are the following:
Circuit 1 trainer kit (EEC471-2 and EEC470), Circuit 1trainer power supply (Feedback Power supply PS445),Analog D.C. milliammeter (100mA dc), Analog D.C.
Voltmeter (20V dc), and Electronic V.O.M.
Fig 1 The circuit used in the experiment
Set first the circuit shown in Figure1 by using the trainerkit and the power supply. Check the circuit connection
carefully. If there is no error, thats the time to turn on thepower supply.
Fig 2 Adjusting the input voltage to 20 Vdc through the use of digitalmultimeter
Set the input voltage to 20 V dc using a digitalmultimeter as shown in Figure 2.
Use ten different resistors in the experiment. Measure
their resistances using a multimeter and record them.Measure and record the voltage and the current flowing ineach trial using different resistor as shown in Figure 3.
Fig 3 Measurement of Current using an ammeter and measurement ofvoltage using a multimeter.
Compute the power consumed in the circuit by using theformula PL= VL* IL. Finally, use the three formulas VL/IL,
PL/IL2, and VL
2/PL to complete the first part of thepreliminary data sheet.
Using Tina Pro software, simulate the circuit diagram
shown in Figure 1. Substitute the values of the resistanceused and record the obtained voltage, current and power asshown in Figure 4.
Fig 4 : Tina Pro software was used to simulate the circuit diagram
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III. RESULTS AND DISCUSSION
In experiment no. 1, the current (IL) flowing through the
circuit and the voltage (VL) across given resistors weremeasured using electrical measuring instruments. Table Ishows the measured data obtained.
TABLEIMEASURED DATA
Given
RL
VL I L PL
258 20.14 V 100 mA 2.01 W
340 20.14 V 62 mA 1.25 W
474 20.14 V 44 mA 0.89 W
677 20.14 V 30 mA 0.60 W
980 20.14 V 21 mA 0.42 W
1 K 20.14 V 20 mA 0.40 W
4.7 K 20.14 V 4.3 mA 0.09 W
22K 20.14 V 1 mA 0.02 W
46.7 K 20.14 V 0.4 mA 8.06 mW
100 K 20.14 V 0.2 mA 4.03 mW
In Table I, the value of VLwhich represents the voltage
across the resistor remains constant even the resistancechanges. This was because; the input voltage was set to
20.14V dc and only one resistor is in the circuit. One cannotice from Table I, as the resistance increases while thevoltage (VL) is held constant, the current (IL) flowingthrough the circuit decreases. This means that when thevoltage is constant, the current is inversely proportional to
the resistance. The results obtained are consistent withOhms Law.
Fig 5. Current versus resistance, based on Table I.
Figure 5 shows the inverse relationship between current
and resistance. When the resistance becomes higher, thecurrent decreases.
Fig 6. Power versus current, based on Table I.
Table I also shows the power consumed by the resistorwhich was computed by multiplying the current (IL) to the
voltage (VL). So when the voltage remains constant, thepower becomes directly proportional to the currentflowing through the circuit. The higher the current, thegreater the power required or consumed. The relationship
of current and power is shown in Figure 6.
Fig. 7 Power versus resistance, based on Table I
0
20
40
60
80
100
120
0 500 1000 1500
Current(mA)
Resistance ()
0
0.5
1
1.5
2
2.5
0 50 100 150
Power(W)
Current (mA)
0
0.5
1
1.5
2
2.5
0 500 1000 1500
Power(W)
Resistance ()
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Figure 7 shows the inverse relationship of resistance andpower. The higher the resistance, the lesser the power
consumed. This was because; the power is directlyproportional to the current, which is inversely proportional
to the resistance when the voltage is held constant.
TABLEIII
COMPUTED RESISTANCE
Given
RL
VL/IL PL/IL2 VL
2/PL
258 201.4 201 201.8
340 324.84 325.18 324.5
474 457.73 459.71 455.75
677 671.3 666.67 676.03
980 959.05 952.38 965.76
1 K 1007 1000 1014.05
4.7 K 4683.72 4867.5 4506.88
22K 20140 20000 20280.98
46.7 K 50.4 K 50.38 K 50.33 K
100 K 100.7 K 100.75 K 100.65 K
Table II shows the values computed for the verificationof resistance using the three formulas, which are derivedfrom Ohms Law and the formula for power. As one cansee in the table, the computed values obtained are quite
near to the resistance (RL) of the resistors used. Thismeans that the resistance can be calculated if at least twofrom power, voltage and current are known.
TABLEIIIII
SIMULATED DATA
Given
RL
VL I L PL
258 20 V 77.52 mA 1.55 W340 20 V 58.82 mA 1.18 W
474 20 V 42.19 mA 843.88 mW
677 20 V 29.54 mA 590.04 mW
980 20 V 20.41 mA 408.16 mW
1 K 20 V 20 mA 0.40 W
4.7 K 20 V 4.26 mA 85.11 mW
22K 20 V 909.09 A 18.18 mW
46.7 K 20 V 428.27 A 8.57 mW
100 K 20 V 200 A 4 mW
Table III presents the simulated values obtained usingTINA Pro software in the computer, which is used to
check if the measured data agree with it. Throughcomparing the two data, the results obtained are quite thesame.
IV. CONCLUSION
Experiment 1 is about the familiarization with electrical
measuring instruments. This experiment is concerned withthe characteristics and the proper connection of commonelectrical measuring devices; the knowledge on readingmeasurements of basic electrical measuring devices; and,
the familiarization with the functions of basic electricaltraining kit and to learn their proper connection.
It is required to get the value for the current (IL) and thevalue for the power (PL) from a constant voltage (VL)source of approximately equal to 20-V with different
known resistance (RL). Current (IL) was obtained using theanalog ammeter, and power was obtained by the formula
PL=ILVLin Table 1.1 and using the TINA software in thesimulated data in Table 1.2.
On the duration of the experiment, it was observed that
when the voltage is constant, as the resistance increases,the current decreases. This shows that the relationship ofthe current and the resistance is inversely proportional ifthe voltage is held constant. On the other hand, power is afunction of voltage and current, PL= ILVL. Also, bycombining the formula of Ohms Law with the formula of
power, then we can derive other formulas to get theresistance.
Lastly, during the preparation of the circuit, we gainedknowledge how to connect the elements and measuringdevices to each other and make a simple circuit
connection. Also how to use and simulate in the TINAsoftware provided to us to verify the measured dataobtained.
ACKNOWLEDGEMENT
This laboratory report would not be possible without theguidance and the help of the individuals who in one wayor another contributed and extended their valuable
assistance in the preparation and completion of this report.
We would like to express our deepest gratitude to our
class mentor, Prof. Paulo Tindogan for his guidance andteachings during the experiment. He helps us to conductthe experiment for us to know what to do.
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We would also like to give thanks to our fellowclassmates for their support and help.
And lastly, we express our deepest thanks to AlmightyGod for His blessings and guidance in our life.
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