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Laboratory Modules Electrical Measurement HIGH VOLTAGE AND ELECTRICAL MEASUREMENT LABORATORY LABORATORY MODULES ELECTRICAL MEASUREMENT ELECTRICAL ENGINEERING DEPARTMENT FACULTY OF ENGINEERING UNIVERSITAS INDONESIA 2018 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. MODULE 1 LABORATORY BRIEFING AND PRE-TEST Laboratory Breifing is held on February 19, 2018 at 18.45 PM located at K building, K301, Faculty of Engineering. Attendance to briefing and pre-test is mandatory and will be included in the scoring system. 2 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. MODULE 2 IMPEDANCE MEASUREMENT I. OBJECTIVE 1. To know LCR Meter and its function 2. To know the construction of LCR Meter and how LCR Meter works II. BASIC THEORY LCR meter is an electronic electrical measurement to measure resistance, inductance and capacitance value. The utilization is relatively easy since today, a digital LCR meter is already in the market, and it makes the user easier to use it. Here is a brief explanation about resistor, inductor and capacitor Resistor is an electronic component that has the function to control and limit electricity. It is also used to limit the amount of current flowing in a circuit. According to its name, resistor is resistive and mostly is made from carbon. The unit of resistance is Ohm and symbolized by omega. Type of resistors mostly has the shape of tube with two copper legs. There are colored circles in the body to make the user know about the resistance without measuring it using measurement device. (example: ohm meter) Figure 1. Resistors types Inductor is symbolized by L. Usually in a form of coil, but sometimes has other forms too. Inductor or coil is one of passive components that is made up by coils and usually save up energy in form of magnetic field. The unit for inductance is called Henry 3 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. (H=Henry, mH = millihenry, etc). An inductor is called as ideal if it has inductance, but has no resistance or capacitance and does not waste much energy. Figure 2. Inductors Types Capacitor is an electronic component that can store electric charge in a certain time. The definition of capacitor is electronic component that save electrical current charge in electric field until a certain time by collecting internal inequity from electric current charge. Capacitor was invented by Michael Faraday (1791-1867). The unit of capacitance is Farad (F). One farad is equal to 9×1011 cm2. Figure 3. Capacitors Types LCR Meter is a part of electronic measurement device to measure inductance (L), capacitance (C) and resistance (R) in component. In the simpler form of this device, the real value of these units is not measured; so that impedance will be measured internally and converted to be shown to capacitance that match or inductance value. The reading will be pretty accurate if capacitor and inductor of device tested do not have impedance significant resistive component. 4 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. The basic resistor measurement principle with LCR-740 is WHEATSTONE bridge. Wheatstone bridge is an electrical circuit consisting of two parallel circuit branches connected with the galvanometer with the aim to measure an unknown electrical load. Wheatstone bridge has four rsistance arms, a source and a detector, usually in the form of galvanometer. Wheatstone bridge can be used to determine the unknown resistance value, for example (see figure 4), suppose R4, we determine the value of the resistor until current through the galvanometer indicates the the value of zero. Wheatstone brigde is said to be in equilibrium if the voltage delta in galvanometer is zero volt, in this case there is no current flowing through galvanometer. At Figure 4, I of Wheatstone bridge will happen if voltage at C to A is equal to voltage from D to A, or if voltage from C to B is equal to D to B. In this case: Figure 4. Wheatstone bridge I1 R1 = I 2 R 2............................................................... ( 1-1 ) If galvanometer shows zero, hence: � �! = �! = . ( 1 – 2 ) �! + �! � �! = �! = . ( 1 – 3 ) �! + �! By substituting equation (1-1),(1-2) and (1-3), we have: � �/(� + � ) ! = ! ! �! �/(�! + �!) 5 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. � � + � ! = ! ! �! �! + �! �!(�! + �!) = �!(�! + �!) If I2 from equation (1-1) is inserted, we got: �!�! �! �! + �! = ∗ (�! + �!) �! �! �!�! �!�! + �!�! = �!�! + �! �!�!�! = �!�!�! �!�! = �!�!. ( 1 – 4) Equation 1-4 is a form of Wheatstone bridge equality. If three of the resistances are known and one of resistance is unknown, for example R4= Rx, hence: �!�! �! = �! Principally, alternating current bridge is used to measure unknown inductance by comparing it with standard known inductor. Figure 5 describes inductance comparator bridge; R1 and R2 are the comparator, and the standard arm is LS in series with RS, whereas LS is high quality inductor and RS is variable resistance. Lx is unknown inductance and Rx is the resistance. 6 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. Figure 5 Inductance Comparator Bridge If the arm of the bridge is stated in complex form, therefore: �! = �! �! = �! + ���! �! = �! �! = �! + ���! In equality: �! ∗ �! = �! ∗ �! �!(�! + ���!) = �!(�! + ���!) �!�! + �!���! = �!�! + �!���! … … … … … (1 – 5) Two complex numbers are the same, if its real and imaginary are the same. By equating real part of equation (1-5), hence: �!�! = �!�! �! �! = �! �! For the imaginary, �!���! = �!���! �! �! = �! �! Principle that is used for capacitance measurement is Capacitancy Comparator Bridge, which is similar to Inductance Comparator Bridge. Figure 6 describes capacitancy comparator bridge. R1 and R2 as comparator arms, and the standard arm is Cs (high quality capacitor) which is series with Rs (variable resistance). Cx is capacitance whose value is unknown and Rx is capacitor leaking resistance. 7 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. Figure 6. Capacitance Comparator Bridge. If the arms of inductance comparator bridge are stated in complex form, therefore: �! = �! �! = �! − �/��! �! = �! �! = �! + �/��! In equilibrium, hence: �! ∗ �! = �! ∗ �! � �!(�! − ) = �!(�! − �/��!) ��! � �!�! − �! = �!�! − �!�/��! … … … … … (1 – 6) ��! The same with inductance comparator bridge, two complex number is the same if its real and imaginary are the same. By equating the real part of above’s equation, we have: �!�! = �!�! �! �! = �! �! Hence, the imaginary is: �!�/��! = �!�/��! �! �! = �! �! 8 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. Equalibirum is obtained by controlling the value of variable load, and variation of load R2 and R1 to obtain minimum current flow in the galvanometer. After that the current that flows thorugh Galvanometer is reduced by varying variable load Rs and keeping R2 and R4 constant. And then keep load Rs constant and change load R2 and R4, repeat the process above until the bridge is in equalibirum. After reaching equalibirum, capacitance can be obtained from the equation above. If the bridge circuit is not ini equalibirum, then the current that flows to the galvanometer causes a deviation of the galvanometer needle. The maginitude of the deviation is a function of the galvanometer’s sensitivity. Hence, the sensitivity is calculated as current per unit(ampere). The galvanometer needle deviation can be expressed linearly or the angle per unit. The sensitivity S can be stated as millimeters derajat radian S = atau ���� µ� µ� µ� Thus the total deviation D is : D = � ×� The thevenin theorem is regularly used to find the current value that flows in the Galvanometer hence the following equation is obtained : �!! I! = �!! + �! III. EXPERIMENT EQUIPMENT 1. LCR Meter 2. Variable Resistor 3. Variable Inductor 4. Variable Capacitor 9 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. IV. EXPERIMENT PROCEDURE 1. Prepare all the equipment that will be utilized. 2. Prepare the components that will be measured. 3. Count manually the value of the components. 4. Then measure the components using RLC Meter. 5. Note the result of measurement. 6. Count total impedance of each load. 7. Find the power factor value from load impedance that is measured on LCR Meter and power factor of load impedance that is stated on the load variable. 8. Compare power factor value of load that is measured by LCR Meter and load that is stated on the load variable. 10 ELECTRICAL MEASUREMENT LABORATORY MODULES High Voltage & Electrical 2018 Measurement Lab. MODULE 3 SINGLE PHASE POWER MEASUREMENT I. OBJECTIVE 1. To know and understand the characteristic of power and power factor measurement on alternating current circuit with different type of loads. 2. To know the working principle of single phase wattmeter, cos phi meter, amperemeter and voltmeter. 3. To understand the variation of power type in alternating current system circuitry. 4. To know the usage of power of light bulb, and compare it with the value of power in its packaging box. II. BASIC THEORY Power in electrical engineering, is defined as the amount of electrical energy that is transferred in an electrical circuit in a time unit (energy per time). Different with direct current direct current circuit, in alternating current circuit, there are 3 kinds of power;
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