Computer-Based Instruments for EMS

Transcription

1 Electric Power / Controls Lab-Volt E E000006~ Computer-Based Instruments for EMS User uide

2 Electric Power / Controls Computer-Based Instruments for EMS User uide E0 A

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5 ELECTRIC POWER / CONTROLS COMPUTER-BASED INSTRUMENTS FOR EMS by the Staff of Lab-Volt Ltd. Copyright 2009 Lab-Volt Ltd. All rights reserved. No part of this publication may be reproduced, in any form or by any means, without the prior written permission of Lab-Volt Ltd. Legal Deposit Fourth Trimester 2009 ISBN FIRST EDITION, DECEMBER 2009 Printed in Canada March 2010

6 Foreword Computer-based teaching technologies are becoming more and more widespread in the field of education, and the Lab-Volt Data Acquisition and Control for Electromechanical Systems (LVDAC-EMS) is witness to this new approach. The LVDAC-EMS system is a complete set of computer-based instruments (metering window, oscilloscope, phasor analyzer, and harmonic analyzer) that runs on an IBM -compatible computer under the Microsoft Windows operating environment. It allows measurement of voltage, current, power, power factor, speed, torque, etc, as well as the observation of electrical signals in both the time and frequency domains, thereby providing students and instructors with tools that clearly demonstrate concepts related to electric power technology. The LVDAC-EMS system is built around the Data Acquisition and Control Interface (DACI) module that interconnects the modules of the Lab-Volt Electromechanical and Power Electronics training systems with a personal computer. The high-level voltages and currents as well as other signals applied to the DACI module are converted into data which is used by the computer running the LVDAC-EMS software to display all the information and measurements related to these voltages, currents, and signals. The LVDAC-EMS system does much more, allowing data storage and graphical representation, as well as a stand-alone mode. It offers great possibilities and versatility in the teaching of electric power technology. We hope that you will have as much pleasure using the LVDAC-EMS system as we had during its development. III

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8 Table of Contents Introduction... VII Section 1 Familiarization with the Metering Window and the Data Table Section 2 Familiarization with the Oscilloscope Section 3 Familiarization with the Phasor Analyzer Section 4 Familiarization with the Harmonic Analyzer Section 5 Measuring Three-Phase Power Using the Metering Window We Value Your Opinion! V

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10 Introduction This user guide is designed to get you familiar with the various computer-based instruments (Metering window, Oscilloscope, Phasor Analyzer, and Harmonic Analyzer) included in the Lab-Volt Electromechanical Training Systems. It is divided into five sections. Each of Sections 1 to 4 deals with a different computer-based instrument. Section 1 allows you to become familiar with the operation of the Metering window. It also shows how to record data in the Data Table and plot graphs using the recorded data. Section 2 deals with the operation of the Oscilloscope. Section 3 describes the operation of the Phasor Analyzer. Section 4 allows you to get familiar with the operation of the Harmonic Analyzer. A step-by-step hands-on exercise in each of these sections shows how to use the corresponding computer-based instrument. Section 5 is a step-by-step hands-on exercise that shows how to measure electrical power in three-phase circuits using the Metering window. This user guide is intended for both instructors and students. It is even recommended that all students perform the hands-on exercises in this guide before they start performing any other hands-on exercises using the Lab-Volt Electromechanical System (EMS). VII

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12 Section 1 Familiarization with the Metering Window and the Data Table INTRODUCTION This familiarization exercise consists of a step-by-step procedure that shows how to use the Lab-Volt computer-based Metering window and Data Table. PROCEDURE CAUTION! High voltages are present in this hands-on exercise. Do not make or modify any banana jack connections with the power on unless otherwise specified. Setting up the Equipment 1. Install the Power Supply, Resistive Load, and Data Acquisition and Control Interface modules in the EMS Workstation. 2. Make sure the Power Supply is turned off and its voltage control knob is set to the 0 position. Connect the Power Supply to a three-phase power receptacle. 3. Connect the LOW POWER INPUT of the Data Acquisition and Control Interface (DACI) module to the 24 V - AC output of the Power Supply. On the Power Supply, set the 24-V AC power switch to the I (on) position. Notice that the POWER INPUT LED on the DACI module lights up to indicate that power is supplied to the module. 4. Connect the equipment as shown in Figure 1-1. Note: The red terminals of inputs E1 and I1 on the DACI module correspond to the terminals marked with a plus (+) sign in Figure

13 Familiarization with the Metering Window and the Data Table Figure 1-1. Simple resistive circuit. Connect the DACI module to the computer. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure 1-1. Measuring Electrical Parameters Using the Metering Window 5. Open the Metering window by choosing the corresponding command in the Instruments menu or by clicking the corresponding button in the EMS Instruments toolbar of the LVDAC-EMS software. 6. In the Metering window, make sure that the Extended Sampling Window is selected. Refer to the Options Menu Command and Acquisition Settings help topics to know how to make this selection. The Metering window is now ready for measuring parameters in the electrical circuit of Figure In the Metering window, set meter E1 as a DC voltmeter and meter I1 as a DC ammeter. Turn on meter PQS1 and set it as an active power (P) meter. Turn off meters E2, E3, I2, and I3. Refer to the Shortcuts to Meter Settings help topic to learn how to change the meter settings. 8. In the Metering window, select the continuous refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Refer to the View Menu Commands help topic to 1-2

14 Familiarization with the Metering Window and the Data Table obtain additional information on the single and continuous refresh modes of the Metering window. Turn on the Power Supply. Observe that meter E1 displays the DC source voltage, meter I1 displays the DC current flowing in the circuit, and meter PQS1 displays the active power dissipated in resistor R 1. Decrease the value of resistor R 1 by closing the other two resistor switches on the Resistive Load module. While doing this, observe that the values displayed by meters E1, I1, and PQS1 change to reflect the decrease in value of resistor R 1, because the meter displays are refreshed at regular time intervals when the continuous refresh mode is selected. 9. In the Metering window, select the single refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure 1-1. While doing this, observe that the values indicated by meters E1, I1, and PQS1 do not change to reflect the change in value of resistor R 1, because the meter displays are not refreshed at regular time intervals when the single refresh mode is selected. In the Metering window, refresh the display by choosing the single refresh command in the View menu or clicking the corresponding button in the toolbar. Observe that this causes the meters to be refreshed so that the values indicated reflect the change in value of resistor R Turn off the Power Supply. Replace the fixed-voltage DC power source with a variable-voltage AC power source, as shown in Figure

15 Familiarization with the Metering Window and the Data Table Figure 1-2. Simple resistive AC circuit. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure In the Metering window, set meter E1 as an AC voltmeter and meter I1 as an AC ammeter. You can refer to the Shortcuts to Meter Settings help topic to know how to change the meter settings. In the Metering window, open the Meter Settings dialog box by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Set programmable meter M5 as a frequency meter (function f (E1)) and programmable meter M11 as an ohmmeter (impedance function RXZ (E1,I1)), turn on these meters, and close the Meter Settings dialog box. Refer to the Options Menu Commands and Meter Settings help topics to obtain additional information on the Meter Settings dialog box. 12. In the Metering window, select the continuous refresh mode. Turn on the Power Supply. Slowly turn the voltage control knob of the Power Supply until the AC source voltage (displayed by voltmeter E1) is approximately equal to the AC power network voltage. While doing this, observe that the meters are refreshed continuously to reflect the variation of the measured parameters. Also observe that programmable meters M5 and M11 indicate the AC power network frequency and the value of resistor R 1, respectively. Set the Power Supply voltage control knob to the 0 position to reduce the AC source voltage to zero. 1-4

16 Familiarization with the Metering Window and the Data Table Recording Data in the Data Table 13. Open the Data Table window by choosing the corresponding command in the Tools menu or by clicking the corresponding button in the Tools bar of the LVDAC-EMS software. Refer to the Overview of the Data Table Window help topic to obtain additional information about the Data Table window. 14. In the Data Table window, record the values indicated by the meters in the Metering window by choosing the corresponding command in the Edit menu or by clicking the corresponding button in the toolbar. The Record Settings dialog box should appear. This box allows you to select the parameters whose values are to be recorded in the Data Table window. The parameters measured by the meters that are turned on in the Metering window should be selected in the Record Settings dialog box (a check mark appears beside each parameter selected). In this case, select E1, I1, PQS1 (E1, I1), f (E1), and RXZ (E1, I1). Refer to the Edit Menu Commands and Options Menu Commands help topics to obtain additional information about data recording and the Record Settings dialog box. Click the OK button in the Record Settings dialog box. This closes the dialog box and record the values indicated by the selected meters in the Metering window in the first row of the Data Table window. 15. On the Power Supply, increase the AC source voltage, in approximately ten steps, until it is approximately equal to the AC power network voltage. For each voltage step, record in the Data Table window the values displayed by the meters in the Metering window. Observe that a new row in the Data Table window is filled up with data whenever a record data command is performed. Set the Power Supply voltage control knob to the 0 position. Turn off the Power Supply. Plotting a raph with the Recorded Data 16. In the Data Table window, open the raph window by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Refer to the Overview of the raph Window help topic to obtain general information about the raph window. 17. In the raph window, plot a graph of the power delivered to resistor R 1 (indicated by meter PQS1) as a function of the voltage applied to this resistor (indicated by meter E1). To do so, select voltage E1 as the X-axis parameter and power PQS1 as the vertical-axis first parameter (1-Y). 1-5

17 Familiarization with the Metering Window and the Data Table Observe that a curve showing the variation of power as a function of voltage appears in the raph window when both parameters are selected. Refer to the Toolbar, X- and Y-Axis Selection Boxes, and Colors help topics to obtain additional information about the raph window. 18. Close the raph window. Close the Data Table window without saving the recorded data. Measuring Mechanical Parameters using the Metering Window This subsection of the procedure can be performed using the Prime Mover / Dynamometer, Model , or the Four-Quadrant Dynamometer / Power Supply, Model If your are using Model , continue the procedure at step 19. On the other hand, if your are using Model , continue the procedure at step Remove all equipment connections except the cable that connects the POWER INPUT of the DACI module to the 24 V - AC output of the Power Supply. Install the Prime Mover / Dynamometer in the EMS Workstation. Connect the fixed-voltage DC power source to the Prime Mover. To do so, connect terminals 8 and N of the Power Supply to the terminals labeled PRIME MOVER INPUT 1 and 2 on the Prime Mover / Dynamometer, respectively. 20. Connect the TORQUE and SPEED OUTPUTs of the Prime Mover / Dynamometer to the AI-7/T (torque) and AI-8/n (speed) ANALO INPUTS of the DACI module, respectively. Connect the common terminal of the Prime Mover / Dynamometer to one of the analog common terminals of the DACI module. These connections are required to measure torque and speed. Connect the POWER INPUT of the DACI module to the LOW POWER INPUT of the Prime Mover / Dynamometer. Notice that the POWER ON LED on the Prime Mover / Dynamometer lights up to indicate that power is supplied to the module. On the Prime Mover / Dynamometer, make the following settings: MODE selector... PRIME MOVER DISPLAY selector...speed 21. In the Data Acquisition and Control Settings window of LVDAC-EMS, set parameter Analog Input AI7 to Torque (NAm). 1-6

18 Familiarization with the Metering Window and the Data Table In the Metering window, turn all meters off then turn the torque (AI-7/T) and speed (AI-8/n) meters on. Turn on the Power Supply. Observe that the prime mover starts to rotate. Also observe that meter AI-8/n indicates the rotation speed of the prime mover and meter AI-7/T indicates the torque produced by the prime mover to overcome the torque that opposes rotation (this torque is mainly due to friction). 22. Turn off the Power Supply. Observe that the torque and speed indicated by meters AI-7/T and AI-8/n, respectively, decrease to zero. In the Metering window, select the single refresh mode. Close the Metering window. Remove all equipment connections. End of procedure. 23. Remove all equipment connections except the cable that connects the POWER INPUT of the DACI module to the 24 V - AC output of the Power Supply. Install the Four-Quadrant Dynamometer / Power Supply in the EMS Workstation. 24. Connect the T and n ANALO OUTPUTS of the Four-Quadrant Dynamometer / Power Supply to the AI-7/T (torque) and AI-8/n (speed) ANALO INPUTS of the DACI module, respectively. Connect one of the analog common terminals of the Four-Quadrant Dynamometer / Power Supply to one of the analog common terminals of the DACI module. These connections are required to measure torque and speed. Connect the POWER INPUT of the Four-Quadrant Dynamometer / Power Supply to a wall receptacle. Turn the Four-Quadrant Dynamometer / Power Supply on by setting the POWER INPUT switch to the I (on) position. On the Four-Quadrant Dynamometer / Power Supply, set the OPERATIN MODE switch to the DYNAMOMETER position. This setting allows the module to operate as a dynamometer or a prime mover depending on the selected function. On the Four-Quadrant Dynamometer / Power Supply, select the Clockwise Prime Mover function by momentarily pressing the FUNCTION button until the function indicated in the module display is CW Prime Mover. 1-7

19 Familiarization with the Metering Window and the Data Table 25. In the Data Acquisition and Control Settings window of LVDAC-EMS, set parameter Analog Input AI7 to Torque (NAm). In the Metering window, turn all meters off then turn the torque (AI-7/T) and speed (AI-8/n) meters on. On the Four-Quadrant Dynamometer / Power Supply, set the speed command of the prime mover to about 1500 r/min using the COMMAND button. The value of the speed command is indicated in the module display. Notice that the speed command shown in the module display is blinking. On the Four-Quadrant Dynamometer / Power Supply, start the prime mover by momentarily pressing the START/STOP button. Observe that the prime mover starts to rotate. Also notice that the speed value in the module display is no longer blinking to indicate that the speed shown is now the actual rotation speed of the prime mover. On the Four-Quadrant Dynamometer / Power Supply, press and hold the FUNCTION button for 3 seconds to have uncorrected torque values on the module display. The indication "NC" appears next to the function name on the module display when uncorrected torque values are indicated. Note: By default, the torque correction function is enabled in the Four-Quadrant Dynamometer / Power Supply. This function can be disabled by pressing and holding the FUNCTION button for 3 seconds. The torque correction function can be enabled again by pressing the FUNCTION button once again for 3 seconds. The status (enabled or disabled) of the torque correction function stays unchanged when another function is selected with the FUNCTION button. In the Metering window, make sure that the continuous refresh mode is selected. Observe that meter AI-8/n indicates the rotation speed of the prime mover and meter AI-7/T indicates the torque produced by the prime mover to overcome the torque that opposes rotation (this torque is mainly due to friction). 26. On the Four-Quadrant Dynamometer / Power Supply, stop the prime mover by momentarily pressing the START/STOP button. Observe that the torque and speed indicated by meters AI-7/T and AI-8/n, respectively, decrease to zero. In the Metering window, select the single refresh mode. Close the Metering window. Turn off the equipment then remove all equipment connections. 1-8

20 Section 2 Familiarization with the Oscilloscope INTRODUCTION This familiarization exercise consists of a step-by-step procedure that shows how to use the Lab-Volt computer-based Oscilloscope. PROCEDURE CAUTION! High voltages are present in this hands-on exercise. Do not make or modify any banana jack connections with the power on unless otherwise specified. Setting up the Equipment 1. Install the Power Supply, Resistive Load, Inductive Load, and Data Acquisition and Control Interface modules in the EMS Workstation. 2. Make sure the Power Supply is turned off and its voltage control knob is set to the 0 position. Connect the Power Supply to a three-phase power receptacle. 3. Connect the POWER INPUT of the Data Acquisition and Control Interface (DACI) module to the 24 V - AC output of the Power Supply. On the Power Supply, set the 24-V AC power switch to the I (on) position. Notice that the POWER INPUT LED on the DACI module lights up to indicate that power is supplied to the module. 4. Connect the equipment as shown in Figure 2-1. Note: The red terminals of inputs E1 and I1 on the DACI module correspond to the terminals marked with a plus (+) sign in Figure

21 Familiarization with the Oscilloscope Figure 2-1. Simple resistive-inductive circuit. Connect the DACI module to the computer. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure 2-1. On the Inductive Load module, set the inductance of inductor L 1 to the value shown in Figure 2-1. Turn on the Power Supply and turn the voltage control knob fully clockwise. Horizontal, Vertical, and Trigger Settings 5. Start the Oscilloscope by choosing the corresponding command in the Instruments menu or by clicking the corresponding button in the EMS Instruments toolbar of the LVDAC-EMS software. 2-2

22 Familiarization with the Oscilloscope 6. Make the following settings on the Oscilloscope: Channel 1 Input (observed parameter)... E1 Scale V/div Invert... Off Coupling... DC Channel 2 Input (observed parameter)... I1 Scale A/div Invert... DC Coupling... Off Time Base... 2 ms/div Trigger Source... Ch 1 Level...0 Slope...Rising Note: If you are using equipment intended for either a 220-V or 240-V AC power network, set the scales of channels 1 and 2 to 200 V/div and 0.2 A/div, respectively. Refer to the Vertical Controls, Time Base, and Trigger Controls help topics to know how to do these settings. 7. On the Oscilloscope, select the continuous refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Refer to the View Menu Commands and Display Refresh help topics to obtain additional information on the single and continuous refresh modes of the Oscilloscope screen. The waveforms of the AC source voltage (E1) and sine-wave current flowing in the circuit (I1) should be displayed on the Oscilloscope screen. Observe that each waveform is displayed using a different color. Also observe that the AC source voltage goes through zero on a positive slope at the beginning of the trace. This corresponds to the trigger settings of the Oscilloscope. Note that the horizontal position of the trigger point can be moved. Refer to the Trigger Controls help topic to know how to move the horizontal position of the trigger point. 8. On the Oscilloscope, change the vertical position of the traces so that the AC source voltage waveform (channel-1 trace) and the sine-wave current waveform (channel-2 trace) are located in the middle of the upper and lower parts of the Oscilloscope screen, respectively. Refer to the Vertical Controls help topic to know how to change the vertical position of the traces on the Oscilloscope screen. 2-3

23 Familiarization with the Oscilloscope 9. Make the following settings on the Oscilloscope: Channel 3 Input (observed parameter)...p1 Scale...20 W/div Invert... Off Coupling... DC Observe that a third sinusoidal waveform appears on the Oscilloscope screen. This waveform shows the power delivered by the AC power source, and is obtained from the voltage and current measured at inputs E1 and I1 of the DACI module. Continuous and Single Refresh Modes 10. On the Power Supply, slowly turn the voltage control knob until it is set to the 60 position. While doing this, observe that the waveforms on the Oscilloscope screen are refreshed at regular intervals to reflect the decrease in the AC power source voltage, because the continuous refresh mode is selected. 11. On the Oscilloscope, select the single refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Observe that the last waveforms acquired remain displayed on the Oscilloscope screen. On the Power Supply, slowly turn the voltage control knob until it is set to the 20 position. While doing this, observe that the waveforms on the Oscilloscope screen do not change, because the Oscilloscope screenis not refreshed at regular intervals when the single refresh mode is selected. On the Oscilloscope, manually refresh the display by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Observe that this causes the waveforms to be refreshed. Notice that the height of the waveforms on the Oscilloscope screen is low because the AC power source voltage has been decreased a lot. On the Oscilloscope, select the continuous refresh mode. Auto Scale Function 12. On the Oscilloscope, use the Auto Scale function. Observe that the scales of channels 1 to 3 are automatically readjusted according to the amplitude of the observed parameters. Refer to the Options Menu Commands help topic to obtain additional information about the Auto Scale function. 2-4

24 Familiarization with the Oscilloscope 13. On the Power Supply, turn the voltage control knob fully clockwise. On the Oscilloscope, use the Auto Scale function to automatically readjust the scales of channels 1 to 3. Waveform Data Section 14. Observe that the Waveform Data section, located under the Oscilloscope screen, indicates the RMS value, average value, and frequency of the observed parameters. Refer to the Waveform Data help topic to obtain additional information on the data provided in this section. 15. On the Oscilloscope, display the vertical cursors by selecting the right option in the Cursors selection box in the Show section of the Oscilloscope settings. Observe that two vertical lines appear on the Oscilloscope screen. These lines are the cursors. Each cursor can be moved horizontally so that it is aligned with a particular point on the observed waveforms. Also observe that the nature of the information in the Waveform Data section of the Oscilloscope changes to indicate values related to the cursors. Refer to the Waveform Data help topic to know how to display and move the cursors. 16. On the Oscilloscope, slowly move cursor 1 so that it is located two divisions from the left-hand side of the screen. While doing this, observe that the Cur 1 column in the Waveform Data section indicates the position in time of cursor 1 and the instantaneous value of each parameter at the intersection of cursor 1 and the corresponding waveform. Move cursor 2 so that it is located six divisions from the left-hand side of the Oscilloscope screen. Observe that the position in time of cursor 2 and the instantaneous value of each parameter at the intersection of cursor 2 are indicated in column Cur 2 of the Waveform Data section. 17. Observe that the Diff column in the Waveform Data section indicates the difference between the instantaneous values of each parameter measured with the two cursors as well as the time interval between these cursors. Refer to the Waveform Data help topic to obtain all information about the Waveform Data section and the cursors. Note that any data in the Waveform Data section can be recorded in the Data Table. Refer to the Edit Menu Commands and Options Menu Commands help topics related to the Data Table to know how to record data. The Data Table window allows graphs to be plotted quickly and easily using the recorded data. On the Oscilloscope, remove the cursors. 2-5

25 Familiarization with the Oscilloscope Storing Waveforms to Memory 18. On the Oscilloscope, select the single refresh mode. The last waveforms acquired remain displayed on the Oscilloscope screen. 19. On the Oscilloscope, store the displayed waveforms in memory 1. Refer to the Memory help topic to know how to store waveforms in memory. Retrieving Waveforms from Memory 20. On the Oscilloscope, select the continuous refresh mode. Turn off the Power Supply. Short-circuit resistor R 1 using a banana plug wire. Turn on the Power Supply. Observe that new waveforms appear on the Oscilloscope screen. Use the Auto Scale function to automatically readjust the scales of channels 1 to 3. On the Oscilloscope, select the single refresh mode to "freeze" the displayed waveforms. 21. Retrieve the waveforms stored in memory 1 a little earlier in this exercise. This allows you to easily compare the waveforms obtained before and after resistor R 1 has been short-circuited. Refer to the Memory help topic to know how to retrieve waveforms from memory. 22. Turn off the Power Supply. Close the Oscilloscope. Remove all equipment connections. 2-6

26 Section 3 Familiarization with the Phasor Analyzer INTRODUCTION This familiarization exercise consists of a step-by-step procedure that shows how to use the Lab-Volt computer-based Phasor Analyzer. PROCEDURE CAUTION! High voltages are present in this hands-on exercise. Do not make or modify any banana jack connections with the power on unless otherwise specified. Setting up the Equipment 1. Install the Power Supply, Resistive Load, Inductive Load, and Data Acquisition and Control Interface modules in the EMS Workstation. 2. Make sure the Power Supply is turned off and its voltage control knob is set to the 0 position. Connect the Power Supply to a three-phase power receptacle. 3. Connect the POWER INPUT of the Data Acquisition and Control Interface (DACI) module to the 24 V - AC output of the Power Supply. On the Power Supply, set the 24-V AC power switch to the I (on) position. Notice that the POWER INPUT LED on the DACI module lights up to indicate that power is supplied to the module. 4. Connect the equipment as shown in Figure 3-1. Note: The red terminals of inputs E1, E2, E3, and I1 on the DACI module correspond to the terminals marked with a plus (+) sign in Figure

27 Familiarization with the Phasor Analyzer Figure 3-1. Simple resistive-inductive circuit. Connect the DACI module to the computer. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure 3-1. On the Inductive Load module, set the inductance of inductor L 1 to the value shown in Figure 3-1. Turn on the Power Supply and turn the voltage control knob fully clockwise. Phasor Selection and Scale Settings 5. Start the Phasor Analyzer by choosing the corresponding command in the Instruments menu or by clicking the corresponding button in the EMS Instruments toolbar of the LVDAC-EMS software. 6. Make the following settings on the Phasor Analyzer: Voltage Scale V/div Current Scale A/div Note: If you are using equipment intended for either a 220-V or 240-V AC power network, set the voltage and current scales to 100 V/div and 0.1 A/div, respectively. 3-2

28 Familiarization with the Phasor Analyzer These settings determine the voltage and current intervals between each circular division on the Phasor Analyzer display. Refer to the Phasor Selection and Scale Setting help topic to know how to do these settings. 7. On the Phasor Analyzer, select voltage E1 (source voltage). Refer to the Phasor Selection and Scale Setting help topic to know how to select the voltages and currents whose phasors are to be displayed. 8. On the Phasor Analyzer, select the continuous refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Refer to the View Menu Commands and Display Refresh help topics to obtain additional information on the single and continuous refresh modes of the Phasor Analyzer display. Observe that a line appears on the Phasor Analyzer display. This line is a phasor that represents voltage E1 (source voltage). The length of phasor E1 corresponds to the RMS value of the AC component of the source voltage. Reference Phasor Selection 9. On the Phasor Analyzer, select voltage E1 (source voltage) as the reference phasor. Refer to the Reference Phasor Selection help topic to know how to do this selection. Observe that phasor E1 now appears at an angle of 0E on the Phasor Analyzer display. This is because the phasor related to voltage E1 has been selected as the reference phasor. The reference phasor is always displayed at an angle of 0E on the Phasor Analyzer display. All other phasors are positioned on the Phasor Analyzer display with respect to the reference phasor. 10. On the Phasor Analyzer, select current I1 (circuit current). Observe that another phasor appears at an angle of about!42e on the Phasor Analyzer display. This phasor represents the current (I1) flowing in the resistiveinductive circuit. The length of phasor I1 corresponds to the RMS value of the AC component of the circuit current. Since the phasors rotate counterclockwise on the Phasor Analyzer display, the displayed phasors clearly demonstrate that current lags voltage in a resistive-inductive circuit. 11. On the Phasor Analyzer, select current I1 (circuit current) as the reference phasor. Observe that the position of phasors E1 and I1 on the Phasor Analyzer display changed. Phasor I1 is displayed at an angle of 0E because it is selected as the reference phasor. Consequently, phasor E1 is displayed at an angle of about 42E. 3-3

29 Familiarization with the Phasor Analyzer Observing Phasors 12. On the Power Supply, slowly vary the setting of the voltage control knob while observing the Phasor Analyzer display. Observe that the length of phasors E1 and I1 varies accordingly. Turn the voltage control knob fully clockwise. 13. On the Resistive Load module, decrease the value of resistor R 1 by closing the other two resistor switches on the Resistive Load module. While doing this, observe that both the length of phasor I1 (circuit current value) and the angular interval between phasors I1 and E1 (phase shift between the circuit current and source voltage) increase to reflect the change in the circuit impedance. 14. On the Phasor Analyzer, select voltages E2 (voltage across resistor R 1 ) and E3 (voltage across inductor L 1 ). Observe that the phasor related to voltage E2 appears at an angle of 0E, because the voltage across a resistor is in phase with the circuit current (phasor I1). Observe that the phasor related to voltage E3 appears at an angle of about 90E, because the voltage across an inductor leads the circuit current (phasor I1) by 90E. Phasor Data Section 15. Observe that the Phasor Data section, located under the Phasor Analyzer display, indicates the RMS value of the AC component of the voltage or current, phase angle, and frequency associated with each of the displayed phasors. Refer to the Phasor Data help topic to obtain additional information on the data provided in this section. 16. On the Resistive Load module, set the value of resistor R 1 to the value shown in Figure 3-1. While doing this, observe that the values in the Phasor Data section change accordingly to reflect the change in the circuit impedance. 17. On the Phasor Analyzer, select the single refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. 3-4

30 Familiarization with the Phasor Analyzer 18. Turn off the Power Supply. Close the Phasor Analyzer. Remove all equipment connections. 3-5

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32 Section 4 Familiarization with the Harmonic Analyzer INTRODUCTION This familiarization exercise consists of a step-by-step procedure that shows how to use the Lab-Volt computer-based Harmonic Analyzer. PROCEDURE CAUTION! High voltages are present in this hands-on exercise. Do not make or modify any banana jack connections with the power on unless otherwise specified. Setting up the Equipment 1. Install the Power Supply, Resistive Load, and Data Acquisition and Control Interface modules in the EMS Workstation. 2. Make sure the Power Supply is turned off and its voltage control knob is set to the 0 position. Connect the Power Supply to a three-phase power receptacle. 3. Connect the POWER INPUT of the Data Acquisition and Control Interface (DACI) module to the 24 V - AC output of the Power Supply. On the Power Supply, set the 24-V AC power switch to the I (on) position. Notice that the POWER INPUT LED on the DACI module lights up to indicate that power is supplied to the module. 4. Connect the equipment as shown in Figure 4-1. Note: The red terminal of input E1 on the DACI module corresponds to the terminal marked with a plus (+) sign in Figure

33 Familiarization with the Harmonic Analyzer Figure 4-1. Circuit used to measure the harmonic contents at the variable-voltage AC output of the Power Supply. Connect the DACI module to the computer. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in Figure 4-1. Turn on the Power Supply and turn the voltage control knob fully clockwise. Harmonic Analyzer Settings 5. Start the Harmonic Analyzer by choosing the corresponding command in the Instruments menu or by clicking the corresponding button in the EMS Instruments toolbar of the LVDAC-EMS software. 6. Make the following settings on the Harmonic Analyzer: Input...E1 Scale Type... % of 1f Scale Setting... 10%/div Fundamental Frequency Type... Network Number of Harmonics...40 Refer to the Harmonic Analyzer Settings help topic to know how to do these settings. Observe that the horizontal axis (frequency axis) of the Harmonic Analyzer display is set to display the first 40 harmonics of the selected input parameter (voltage E1, i.e. the AC source voltage). 4-2

34 Familiarization with the Harmonic Analyzer Observe that the vertical scale of the Harmonic Analyzer display is graduated in percentage of the fundamental-frequency component (% of 1f) with a progression of 10% per division. Observation of Harmonic Contents 7. On the Harmonic Analyzer, select the continuous refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Refer to the View Menu Commands and Display Refresh help topics to obtain additional information on the single and continuous refresh modes of the Harmonic Analyzer display. Observe that a vertical bar appears in the Harmonic Analyzer display. This bar corresponds to the fundamental frequency component of the AC source voltage, that is, the component at the AC power network frequency. 8. On the Harmonic Analyzer, gradually increase the sensitivity (by decreasing the Scale Setting). While doing this, observe that a few other harmonic components gradually appear on the Harmonic Analyzer display. These components should have fairly low levels because the waveform of the AC power network voltage is close to that of a pure sine wave. 9. Observe that the Levels section of the Harmonic Analyzer indicates the value of the DC component and the first forty harmonics of the selected input parameter (voltage E1, i.e. the AC source voltage). Also observe that each value is expressed as a percentage of the fundamental-frequency component, as in the Harmonic Analyzer display. You can refer to the Harmonic Analyzer Settings help topic to obtain additional information about the Levels section. 10. Observe that the THD and THD1 Distortion displays indicate the total harmonic distortion (THD) in the selected input parameter (voltage E1). Both values should be low and almost identical because THD in the AC power network voltage is normally low. Refer to the Harmonic Distortion Display help topic to obtain additional information about the nature of the values indicated by the THD and THD1 Distortion displays. 11. On the Harmonic Analyzer, set the number of harmonics to 20. Observe that the Harmonic Analyzer now displays only the first 20 harmonics of the selected input parameter (voltage E1). 4-3

35 Familiarization with the Harmonic Analyzer Cursors 12. On the Harmonic Analyzer, display the vertical cursors. Observe that two vertical lines appear on the Harmonic Analyzer display. These lines are the vertical cursors. Each cursor can be moved horizontally so that it is aligned with a particular harmonic component. Refer to the Harmonic Analyzer Cursors help topic to know how to display and move the vertical cursors. 13. On the Harmonic Analyzer, align cursor 1 with the first harmonic (fundamental-frequency component), and cursor 2 with the third harmonic. Observe that column Cur 1 in the Cursors section, located under the Harmonic Analyzer display, indicates the number, frequency, and level of the harmonic on which cursor 1 is aligned. Column Cur 2 provides the same information about the harmonic on which cursor 2 is aligned. You can refer to the Harmonic Analyzer Cursors help topic to obtain additional information about the Cursors section. Note that any value indicated in the Cursors section, Levels section, and Distortion displays of the Harmonic Analyzer can be recorded in the Data Table. Refer to the Data Recording help topic to know how to record data in the Data Table. The Data Table window allows graphs to be plotted quickly and easily using the recorded data. 14. On the Harmonic Analyzer, set the Scale Type to voltage (V). Observe that the vertical scale of the Harmonic Analyzer is graduated in volts (RMS values). Observe that all values in the Levels section and the Level data fields of the Cursors section are also expressed in volts (RMS values). 15. On the Harmonic Analyzer, remove the vertical cursors. Note that horizontal cursors similar to the vertical cursors are also available. Refer to the Harmonic Analyzer Cursors help topic to know how to display and move the horizontal cursors. 16. On the Harmonic Analyzer, select the single refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. 17. Turn off the Power Supply. Close the Harmonic Analyzer. Remove all equipment connections. 4-4

36 Section 5 Measuring Three-Phase Power Using the Metering Window INTRODUCTION This section contains an easy hands-on exercise that demonstrates how to measure three-phase power using the Lab-Volt computer-based Metering window. The exercise consists of a step-by-step procedure that shows you two methods for measuring electrical power in three-phase circuits. PROCEDURE CAUTION! High voltages are present in this hands-on exercise. Do not make or modify any banana jack connections with the power on unless otherwise specified. Setting up the Equipment 1. Install the Power Supply, Resistive Load, and Data Acquisition and Control Interface modules in the EMS Workstation. 2. Make sure the Power Supply is turned off and its voltage control knob is set to the 0 position. Connect the Power Supply to a three-phase power receptacle. 3. Connect the POWER INPUT of the Data Acquisition and Control Interface (DACI) module to the 24 V - AC output of the Power Supply. On the Power Supply, set the 24-V AC power switch to the I (on) position. Notice that the POWER INPUT LED on the DACI module lights up to indicate that power is supplied to the module. 4. Connect the equipment as shown in Figure 5-1. Note: The red terminals of inputs E1 and I1 on the DACI module correspond to the terminals marked with a plus (+) sign in Figure

37 Measuring Three-Phase Power Using the Metering Window Figure 5-1. DACI module connections used to measure power in balanced three-phase circuits. Connect the DACI module to the computer. On the Resistive Load module, set the resistance of resistors R 1, R 2, and R 3 to the value shown in Figure 5-1. Measuring Power in Balanced Three-Phase Circuits Using the Metering Window 5. Open the Metering window by choosing the corresponding command in the Instruments menu or by clicking the corresponding button in the EMS Instruments toolbar of the LVDAC-EMS software. 6. In the Metering window, make sure that the Extended Sampling Window is selected. Refer to the Options Menu Command and Acquisition Settings help topics to know how to make this selection. The Metering window is now ready for measuring parameters in the threephase circuit of Figure In the Metering window, set meter E1 as an AC voltmeter and meter I1 as an AC ammeter. Turn off meters E2, E3, I2, and I3. Refer to the Shortcuts to Meter Settings help topic to learn how to change the meter settings quickly. 5-2

38 Measuring Three-Phase Power Using the Metering Window 8. In the Metering window, select the continuous refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. If necessary, refer to the View Menu Commands help topic to obtain additional information on the single and continuous refresh modes of the Metering window. 9. Turn on the Power Supply. Set the voltage control knob of the Power Supply so that the line-to-line voltage (displayed by voltmeter E1) is approximately equal to the value given in the following table. AC NETWORK VOLTAE (V) LINE-TO-LINE VOLTAE (V) Table 5-1. Line-to-line voltage of the circuit. Record the line-to-line voltage and line current (displayed by ammeter I1) in the following blank spaces. Line-to-Line Voltage (E L-L ) : V Line Current (I L ) : A 10. Using the measured parameters and the following equation, calculate the active power dissipated in the circuit. P = E L-L x I L x cosn x 1.73 P = = W Note: Cosn is equal to 1 because the circuit load is resistive only. 11. In the Metering window, open the Meter Settings dialog box by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. Set programmable meter M5 as a three-phase active power meter by selecting power function PQS1 (E1,I1) 3- and the active power (P) mode. Turn on programmable meter M5 and close the Meter Settings dialog box. Refer to the View Menu Commands and Meter Settings help topics to obtain additional information on the Meter Settings dialog box. 5-3

39 Measuring Three-Phase Power Using the Metering Window Observe that programmable meter M5 displays active power, the displayed value being very close to the three-phase active power calculated in the previous step. This method of measuring three-phase power using a single line-to-line voltage and a single line current is valid when the three-phase circuit is balanced. Note: Three-phase power in balanced circuits can also be measured using power function PQS2 (E2,I2) 3~ and inputs E2 and I2 of the DACI module, power function PQS3 (E3,I3) 3~ and inputs E3 and I3 of the DACI module, or power function PQS4 (E4,I4) 3~ and inputs E4 and I4 of the DACI module. 12. Set programmable meter M5 as a reactive power (Q) meter. Observe that the three-phase reactive power displayed by programmable meter M5 is nearly zero. This is normal because a resistive load draws a negligible amount of reactive power from the three-phase power source. 13. Set programmable meter M5 as an apparent power (S) meter. Observe that the three-phase apparent power displayed by programmable meter M5 is equal to the three-phase active power measured previously. This is normal because a resistive load draws a negligible amount of reactive power from the three-phase power source. Measuring Power in Three-Phase Circuits Using the Metering Window (Two Wattmeter Method) 14. Turn off the Power Supply without modifying the setting of the voltage control knob. Modify the connections so that the DACI module is connected as shown in Figure 5-2. Note: The red terminals of inputs E1, E2, I1, and I2 on the DACI module correspond to the terminals marked with a plus (+) sign in Figure

40 Measuring Three-Phase Power Using the Metering Window Figure 5-2. DACI module connections used to measure power in three-phase circuits (two wattmeter method). Turn on the Power Supply. 15. Open the Meter Settings dialog box. Set programmable meter M11 as a three-phase active power meter (twowattmeters method) by selecting power function PQS1 + PQS2 and the active power (P) mode, then turn on programmable meter M11. Set programmable meter M5 as an active power (P) meter, then close the Meter Settings dialog box. Notice that programmable meter M11 indicates active power, the displayed value being virtually equal to the active power displayed by programmable meter M5, and very close to the three-phase active power calculated in step On the Power Supply, set the voltage control knob so that the line-to-line voltage (displayed by voltmeter E1) is approximately equal to the value given in the following table. 5-5

41 Measuring Three-Phase Power Using the Metering Window AC NETWORK VOLTAE (V) LINE-TO-LINE VOLTAE (V) Table 5-2. Reduced line-to-line voltage of the circuit. Observe that the three-phase active power displayed by programmable meters M5 and M11 decreased because the line-to-line voltage has been decreased. 17. On the Resistive Load module, set the resistance of resistor R 1 to the value shown in the following table to unbalance the three-phase load. While doing this, observe that the values of active power displayed by programmable meters M5 and M11 change because the three-phase circuit is now unbalanced. AC NETWORK VOLTAE (V) R 1 (Ω) Table 5-3. Value of resistor R 1. Observe that the values of three-phase active power displayed by programmable meters M5 and M11 differ. The correct value is displayed by programmable meter M11 because the two wattmeter method of measuring power is valid whether or not the three-phase circuit is balanced. 18. In the Metering window, select the single refresh mode by choosing the corresponding command in the View menu or by clicking the corresponding button in the toolbar. 19. Turn off the Power Supply. Close the Metering window. Remove all equipment connections. 5-6

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