Power Measurements on AC-DC Power Supplies
Contents
1. 5 PWRVIEW Software PWRVIEW software compliments Tektronix Power Analyzers and is available as free download on Tektronix website PWRVIEW offers easy wizard driven test solutions for power supply standby power and many other target applications For download and installation info go to www tek com power analyzer series pa1 O00 Features m Jektronix Power Analyzers remote operation m transfer view analyze record and export measurement data in real time from the instrument including waveforms harmonic bar charts and stand power trend charts m Default applications and standard compliance tests m Figure 13 shows the screen shot of PWRVIEW PC software m PWRVIEW makes is very easy to monitor record and analyze the critical power measurement that have been discussed earlier m The following section will demonstrate how to make efficiency measurements using two PA1000 using PWRVIEW software 10 www tektronix com power analyzer Figure 14 Adding two PA1000 simultaneously 6 Power Supply Efficiency Measurements Two wattmeter channels are required for performing the efficiency measurements Either a multichannel Power Analyzer like PA4000 or two PA1000 connected with PWRVIEW can do the job Two PA1000 s are used for this example to demonstrate efficiency measurements on a power supply P OUT 100 Piy Efficiency m Connect two PA1000 s one on input and one on output of the power supply under2. Power Measurements on AC DC Power Supplies Application Note Tektronix Application Note Table of Contents 1 Mtrod cth n sunnin nA EAEN 2 Power Supply Measurements Essential AC COUN see EERE 3 Critical Power Supply Measurements 4 Making Power Supply Input Measurements Using a Tektronix PA1000 ee ceeeeeeeeeeeeees 5 PWRVIEW Software ccccceeeeeeseseeeeeseeeseenenees 6 Power Supply Efficiency Measurements 7 Standby Power Compliance Tests 0 2 www tektronix com power analyzer 10 11 BIE a E EE 13 8 1 RMS Root Mean Squared Value cceceeeeeeeeeeees 13 8 2 Average Value cceccseecseecseceeceeeceeeceesaeeeaseeaneeanss 14 8 3 Real and Apparent Power W amp VA seeseeseseeerrees 14 oe PONG E CIO eran r verse ice 16 oa oS C OT ea E EE 17 8 6 Harmonic DIStOrtion ccccccceeeeeeeeeeeeeeeeeeeeeeeeeeaeees i7 Sef Standby POWE semcncscttreninientiacbaaiteneiantienteatenienos 17 CONCUSSION wasencutsuceasevenmsaesavennmsennuvaesaseete weseuccuteenae 18 Reference ssssssnssunnunnnnennnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnn nne 18 Appendix A ssssnssnsnnnnnnnnsnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nenne 19 Tektronix Power Analyzers INtroduction cccceeee eee es 19 Power Measurements on AC DC Power Supplies 1 Clock Passive Components E Active Components Magnetics Voltage Time Pe
3. and that power factor is not equal to cos in any other case Figure 24 I3 This must be remembered when using a power factor meter that reads cos as the reading will not be valid except for pure sinusoidal voltage and current waveforms A true power factor meter will compute the ratio of real to apparent power as described in section discussing real and apparent power Tektronix power analyzer retains high accuracy even at very low power factor which is very important for product Characterization and development 8 5 Crest Factor Tektronix power analyzers can measure a high Crest Factor 10 This is critical for characterization of switched mode power supplies which usually have high peak current draw It has already been shown that for a sinusoidal waveform Peak Value RMS x v2 The relationship between peak and RMS is Known as the crest factor and is defined as Peak Value RMS Value Crest Factor Thus for a sinusoid Crest Factor V2 1 41 Many items of modern equipment connected to the AC supply take non sinusoidal current waveforms These include power supplies lamp dimmers and even fluorescent lamps Power supplies can often exhibit a current crest factor of around 4 and up to 10 8 6 Harmonic Distortion If a load introduces distortion of the current waveform it is useful in addition to knowing the crest factor to quantify the level of distortion of the wave shape Observation on an osc
4. crest factors power factor Current and voltage harmonics THD active and reactive power and many more Please refer to the user manual for the list of all available measurements Figure 9 shows an example of some of these measurements on the display m Voltage current and power waveforms and harmonic bar charts can also be viewed as seen in following Figure 10 and Figure 11 respectively by pressing the Graph button or accessing the Graph Menu Power Measurements on AC DC Power Supplies Arms 409 91 mA Watt 29 2 UW 60 0 16 0m 20 0m Figure 10 Graph display a Figure 12 Data logged to Excel file One of the important features that most of the power supply designers and testing labs need is ability to log data efficiently over extended periods of time PA1000 provides a standard USB port on the front panel for data logging which can be very handy for performing extended testing The test results can be exported as an excel file and used for presentation or analysis as shown in the Figure 12 m he best and the most convenient way to test power supply is to use the included PWRVIEW software www tektronix com power analyzer 9 Application Note img Mownwe Taw fru HHO 00 f Seve Erori Upinsd Adi Ronee Note sh Defautt Appixstiora x e a homa we Ay yt Voltage Chasre maj a Crrent Chennai ne s rama da Meaeurersemt Selkteni a ew rad Figure 13 PWRVIEW software
5. the load www tektronix com power analyzer 15 Application Note Voltage J is 0 0 Cos 0 1 PF 1 No Phase Shift fi fo s Sine current J YS lt 0 60 Cos 0 0 5 PF 0 5 Phase Shift 1 f s Sine current I a 0 60 Cos 0 1 PFx1 No Phase Shift Non Sinusoidal current I I Figure 24 Power factor waveform 8 4 Power Factor It is clear that in comparison with DC systems the transferred AC power is not simply the product of the voltage and current values A further element known as the power factor must also be taken into consideration In the previous example real 16 www tektronix com power analyzer and apparent power with an inductive load the power factor is 0 5 because the useful power Is exactly one half of the apparent power We can therefore define power factor as Real Power Power Factor Apparent Power In the case of sinusoidal voltage and current waveforms the power factor is actually equal to the cosine of the phase angle 0 between the voltage and current waveforms For example with the inductive load described earlier the current lags the voltage by 60 degrees Therefore Power Factor cos0 cos60 0 5 lt is for this reason that power factor is often referred to as cos However it is important to remember that this is only the case when both voltage and current are sinusoidal Figure 24 l1 and 12
6. ak Current RMS Current Current Time Figure 1 Switch mode power supply simplified schematic 1 Introduction AC to DC power supplies are fully integrated into our daily lives They are the heart of all our electronics providing energy for the everyday devices that we rely on A cell phone charger is a power supply but so are the power electronic circuits embedded inside almost any electronics or appliance connected to the AC line This near universal use of power supplies means that although the power that each individual supply draws is small the cumulative effects are very significant For this reason it is desirable and often required by regulation to control power supply characteristics such as efficiency AC DC Power supplies convert electrical energy from their AC line input to provide DC outputs that are m solated from the dangerous high voltage high capacity AC line m Smoothed and low noise DC voltage Regulated to be largely independent of input voltage changes m Current controlled to avoid damage to the load especially batteries and to the power supply itself Typically an AC to DC power supply converts the AC line 110 220V 50 60HZ into low voltage 12 5 3V DC Power supply designers strive to improve the efficiency of their designs while maintaining specified performance over a range of inout and load conditions and complying with demanding international regulations for harmonic cur
7. be larger than required to supply the necessary power watts and that power is wasted providing the excess current by resistive losses in the transmission and distribution system This is one reason why the current distortion drawn by power supplies is limited by international regulations such as IEC61000 3 2 www tektronix com power analyzer 3 Application Note Voltage Test Points PWM control Figure 3 Simplified view of an SMPS power supply primary side only and its power quality measurement test points Simultaneous input VAC and IAC readings are necessary for power quality measurements Most modern power supply designs mitigate this problem by employing some form of wave shaping circuit on their inout often called a PFC Power Factor Correction circuit An example of PFC implementation is shown in Figure 3 These circuits helo shape the input current such that the Inout impedance of the power supply appears fairly linear to the power line similar to a resistive load By doing so the problems of distorted input current waveforms can be significantly improved Another key issue most designers face today is measuring and certifying energy consumption and efficiency on their class of device to comply with institutions like ENERGY STAR and CEC In order to satisfy these requirements for low input current distortion and harmonics high efficiency and low average and standby power consumption its important to understand
8. cuits a voltage divider and a current shunt to provide power measurements with a basic accuracy of 0 04 or better This class of accuracy is required to confirm high levels of accuracy as well as for conformance to power and harmonics standards 20 www tektronix com power analyzer For example a typical oscilloscope and probe combination may provide 3 of amplitude accuracy for voltage and current The total power uncertainty will be even greater resulting in 3 uncertainty for overall power and efficiency measurements This can be very important when designing to achieve a high efficiency For example a nominal 90 efficiency may be as high as 93 or as low as 87 when measured with an oscilloscope This uncertainty could then result in either a non conforming design measuring above 90 but actual efficiency less than 90 or unnecessary extra design optimization measuring below 90 but actual efficiency already greater than 90 Tektronix Power Analyzer Key Feature Summary m Best in class accuracy from mW to kW Best in class 0 04 basic accuracy to validate even the most efficient designs Only standby power solution that shows the required uncertainty from SmW up m Unique user limit system in PWRVIEW software for PASS FAIL testing 1MS s continuous sampling Color display shows waveforms and harmonic barcharts m Best value for performance and features Power Measurements on AC DC Power Supplies www tektroni
9. d other resources to help engineers working on the cutting edge of technology Please visit www tektronix com Copyright 2014 Tektronix All rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specification and price change privileges reserved TEKTRONIX and TEK are registered trademarks of Tektronix Inc All other trade names referenced are the service marks trademarks or registered trademarks of their respective companies 08 14 EA WWW 55W 29828 1
10. e heating effect at any instant is given by the equation W 1 R Power Measurements on AC DC Power Supplies By dividing the current cycle into equally spaced coordinates samples the variation of the heating effect with time can be determined as shown in Figure 2 above The average heating effect ower is given by LF R ER ER 1 R n To determine the equivalent value of current that would produce the average heating effect value shown above then the following applies CR ER R I R 2 I n Therefore 2 2 2 2 L L 43 4 0 n The RMS value of the current the square root of the mean of the squares of the current This value is often termed the effective value of the AC waveform as it is equivalent to the direct current that produces the same heating effect power in the resistive load It is worth noting that for a sinusoidal waveform peak value v2 RMS value RMS 0 707 x peak value www tektronix com power analyzer 13 Application Note True RMS Time Figure 22 Average calculated methodology 8 2 Average Value The average value of a waveform such as that shown in Figure 22 is given by Area enclosed by one half cycle Average Value Length of base over one half cycle It is clear the average value can only have real meaning over one half cycle of the Waveform for a symmetrical waveform the mean or average value over a complete cycle is zero Most sim
11. est Factor Analyzing current waveforms with high peak value THD Total Harmonic Distortion Required to analyze the effect of non lineanity s Standby Power Required of Energy Star and IEC62301 Table 1b 6 www tektronix com power analyzer Required for compliance optimizes use of available Real Power Power Factor Apparent Power Instruments with high crest factor measurement Capability are able to analyze these typical switch mode waveforms Voltage Peak Current RMS Current Current Power DSP analysis capability for accurate measurement of THD A year 2000 study in the US claimed that standby power accounted for around 10 of household power consumption 6 billion Shown here an IEC62301 test report asv asov nov arov aov PASS CESES 10 00 wa wa wa gt O k Breakout Box PF e Device under test Figure 5 PA1000 wiring diagram 4 Making Power Supply Input Measurements Using a Tektronix PA1000 Tektronix PA1000 is a single channel high precision Power Analyzer that helos makes complex power measurements on a power supply very easy This section will discuss a practical example of making power supply inout measurements on a typical power supply The DUT Device under test for this example is a generic laptop charger Wiring The standard current inputs of a power analyzer will measure a large range of current from milli amps to 20 o
12. how to measure them in accordance with internationally accepted practice 4 www tektronix com power analyzer Current Average Heating Effect Figure 4 Distorted input current sampling 3 Critical Power Supply Measurements Its important for a power supply designer to keep check of all these parameters that are so crucial to a power supply s performance proper operation and compliance to specification Some of the most important power measurements a designer has to make are listed as follows Power Measurements on AC DC Power Supplies Critical Power Supply Measurements Volts RMS Line regulation drop out Amps RMS voltage testing power fail Circuits Input and Power Consumption Output Power VA Apparent power VRMS x ARMS Table 1a Critical for Power Meter Essentials True RMS measurements made with high frequency waveform sampling a Positive Peak Mid ordinates Negative Halfcycle 1 1234567891 Positive Halfcycle 1 EY Negative Peak One Complete Cycle Non linear current and voltage sampled and Current averaged to provide RMS Watts the equivalent dc heating effect Heating Effect Measurement is independent of phase between voltage and current V VRMS IRMS www tektronix com power analyzer 5 Application Note Critical Power Supply Measurements Critical for Power Meter Essentials PF Power Factor voltage and current CF Cr
13. illoscope will indicate distortion but not the level of distortion It can be shown by Fourier analysis that a non sinusoidal current waveform consists of a fundamental component at the supply frequency plus a series of harmonics i e components at frequencies that are integral multiples of the supply frequency For example a SMPS a lamp dimmer or even a speed controlled washing machine motor can contain harmonics of even greater significance as shown in Figure 25 The only useful current is the fundamental component of current as it is only this that can generate useful power The additional harmonic current not only flows within the power supply itself but in all of the distribution cables transformers and switchgear associated with the power supply and will thus cause additional loss There is an increasing awareness Power Measurements on AC DC Power Supplies Figure 25 An example of Harmonics Barchart of the need to limit the level of harmonics that equipment can produce Controls exist in many territories to provide mandatory limits on the level of harmonic current permitted for certain types of load Such regulatory controls are becoming more widespread with the use of internationally recognized standards such as EN61000 3 2 Thus there is a need for an increased awareness amongst equipment designers as to whether their products generate harmonics and at what level It is only the fundamental which generates power har
14. monics in general do not 8 Standby Power Standby power is the power drawn by a power supply when its load is not performing its full function This may be the power consumed just by the clock on a microwave oven or the power drawn by a laptop charger when the battery Is fully charged To make the measurement requires not only very low measurement ranges but special techniques to overcome the problems of power supplies operating in burst mode Tektronix power analyzers have both a quick 1 button standby mode for the designer and together with PWRVIEW pc software will perform full compliance ENERGY STAR and IEC62310 Ed 2 standby power measurements Please see our detailed application note on this subject www tektronix com power analyzer 17 Application Note 9 Conclusion Power and power related measurements on power supplies require sophisticated and accurate instrumentation to ensure that the power supply performs to its specification The Tektronix PA1000 power analyzer incorporates a wide range of advanced features that provide class leading accuracy from mW to kW With the PA1000 Power supply designers faced with the challenges of ever increasing efficiency and lower standby power requirements can always be confident that their designs meet specifications 18 www tektronix com power analyzer 10 Reference m Standby Power Measurement Primer www tek com application standby power measurements m PA1000 Power Analyze
15. orm This is the simplest most intuitive method and avoids any problems of clipping or de rating the specification according to crest factor In this way the accuracy specifications contain no additional factors even for waveforms with high crest factors up to 10 Measurements can be made satisfactorily with crest factors of 20 or more This is important for power supplies that experience high crest factors on their input current as discussed earlier Power meters with traditional RMS ranging often require user intervention a crest factor setting and modified uncertainty specification before the measurement to be correctly interpreted The peak ranging feature on Tektronix power analyzers helps with no compromise results while measuring highly distorted waveforms as shown in Figure 26 www tektronix com power analyzer 19 Application Note 200A sear Figure 27 Patent pending spiral shunt Spiral Shunts It is important that a power analyzer provides consistent results independent of current level and over 1 year calibration interval Tektronix Power Analyzers include the patent pending spiral shunt design shown in Figure 27 This unique form helps to provide stable and accurate measurements results over a wide range of temperature conditions and load currents as well as increased tolerance to overload and minimum stray inductance Accuracy A power analyzer connects directly to the AC line and uses precision input cir
16. ple multi meters determine AC values by full wave rectification of the AC waveform followed by a calculation of the mean value Such meters however will be calibrated in RMS and will make use of the Known relationship between RMS and average for a sinusoidal waveform i e RMS 1 11 x mean However for waveforms other than a pure sine wave the readings from such meters will be invalid RMS values will need to be calculated using techniques shown in Figure 22 14 www tektronix com power analyzer 8 3 Real and Apparent Power W amp VA A sinusoidal voltage source of say 100V RMS is connected to a resistive load of say 100 Q then the voltage and current can be depicted as in Figure 23 and are said to be in phase The power that flows from the supply to the load at any instant is given by the value of the product of the voltage and the current at that instant as illustrated in Figure 23 From this tt can be seen that the power flowing into the load fluctuates at twice the supply frequency between O and 200W and that the average power delivered to the load equals 100W which is what one might expect from 100V RMS and a resistance of 100 Q However if the load is reactive i e contains inductance or capacitance as well as resistance with an impedance of 100 Q then the current that flows will still be 1A RMS but will no longer be in phase with the voltage This is shown in Figure 24 for an inductive load with the curren
17. r www tek com power analyzer pa1 O00 m PA1000 Accessories Break out Box www tek com datasheet power analyzer transducer 11 Appendix A Tektronix Power Analyzers Introduction A power analyzer is high precision measurement instrument designed specifically to measure power and related parameters Measurements include m Power watts m Efficiency m Low power standby mW m Apparent power VA m True RMA V and A m Power Factor m nrush Current m Crest Factors and Peak Values m Harmonics V A and W m THD V A Tektronix power analyzers are digital sampling instruments They take simultaneous samples of the voltage and current waveforms continuously and at high speed and then process the samples to provide the measured quantities according to their strict mathematical definitions Features that enable Tektronix analyzers to provide accurate measurements reliably and quickly for power supply measurements include peak ranging and our patent pending SpiralShunt technology Power Measurements on AC DC Power Supplies N ji t a tt A ter a d ome rer a J SPASE rat j f IE A i p a i anaE e eam i a aa fall S on amamma Figure 26 Peak ranging for high crest factor waveforms Peak Ranging Tektronix Power Analyzers are fully auto ranging with a wide dynamic range Unlike most other analyzers Tektronix choose and specifiy the measuring range based on the peak value of any wavef
18. r 30 amps RMS This is suitable for most power supplies up to 3kW A single power analyzer wattmeter input channel consists of a voltage input pair V and V o and a current input pair A and A Lo Power Measurements on AC DC Power Supplies Figure 6 Result screen Figure 7 These connections are simplified by use of a break out box that makes the analyzer connections with 4mm safety connectors and provides a standard AC outlet for connection to the power supply Make the connections as shown in the Figure 5 www tektronix com power analyzer 7 Application Note Figure 8 Measurements menu 8 www tektronix com power analyzer Connect the PA1000 and breakout box using the color coded safety banana lead set as seen in picture For this example a generic laptop charger was plugged in the AC socket on the breakout box and allowed to charge a laptop PA1000 will start displaying results as soon as everything is plugged in and powered on as shown in Figure 6 To view more parameters press the Menu button on the front panel and navigate to Measurements as shown in Figure 8 Vres 1720 04 arms 408 9 Watt 29 24 w Freq 60 02 PF 0 596 va 49 09 var 39 43 var vpk 165 43 vpk 165 41 v Apk 1 342 pk 1 316 A Vde 15 461 vind 2 448 athd 118 82 Figure 9 More measurement choices i gt ee sR a Figure 11 Harmonic bar chart display m Options available include
19. rent content standby power safety and EMC This application note is intended to assist engineers who design and test power supplies and other equipment connected to the AC line make power related measurements accurately quickly and safely Figure 2 Vrms and Arms waveform 2 Power Supply Measurements Essential Background AC Power is the product of RMS input voltage RMS input Current and power factor The power supply input voltage is the normal AC line in most cases and its shape is near sine wave with low distortion The input current may be highly distorted and rich in harmonic content Most power supplies have input circuits consisting of arectifier followed by a smoothing capacitor to produce a high voltage DC The capacitor maintains the DC voltage when the AC line input voltage is falling and is charged only when the AC voltage is higher than the DC bus voltage The AC input current is thus no sine wave but only flows near the peak of the voltage sinewave An example of a typical switch mode power supply is shown in Figure 1 Figure 2 shows typical inout waveforms of a power supply This distorted current increases the RMS current drawn from the AC line but does no useful work and does not contribute to the real power watts drawn or used by the power supply This extra wasted current multiplied up by the millions of power supplies in use means that the the AC supply and distribution system must
20. t lagging by 60 degrees Although the power flow continues to fluctuate at twice the supply frequency it now flows from the supply to the load during only a part of each half cycle during the remaining part it actually flows from the load to the supply The average net flow into the load therefore is much smaller than in the case of a resistive load as shown in Figure 23 with only SOW of useful powering delivered into the inductive load In both of the above cases the RMS voltage was equal to 100V RMS and the current was 1A RMS The product of these two values is the apparent power delivered into the load and is measured in VA as follows Apparent Power Vrys X Arus The real power delivered has been shown to depend on the nature of the load It is not possible to determine the value of real power from the Knowledge of RMS voltage and the use of a true AC power meter capable of computing the product of the instantaneous voltage and current values and displaying the mean of the result is required VA is often measured to ensure that the ac supply has sufficient capacity Power Measurements on AC DC Power Supplies 1 Arms 2 100 Vans 1000 Voltage Current 100W Average Power Time Figure 23 Voltage and current phase waveform 1 Arms 2 100 Vons 1000 Time Time Power lost due phase different between Current and Voltage Figure 24 The power that flows from the supply to
21. te on www tek com 12 www tektronix com power analyzer Tektronix PWRVIEW Setup Measure Test Results v Laboratory Tektromix UK Lid gt Ss gt i Customer Customer ABC gt Manage Save Test Tuli Export Product POR 123 iso Repat CN 3334353333 Ce e i r r r E S E i SH HS r a E o E HSH 10 Figure 20 PWRVIEW PC software charts harmonics and compares to limits Harmonics Limits Using PC software coupled to the power analyzer harmonics measurements may be quickly and conveniently recorded and compared to the limits of IEC61000 3 2 and others Software features such as PDF report export provide complete reporting functions for power supply conformance measurements Current Time Average Heating Effect 7 all Time Figure 21 Root Mean Square waveform 8 Definitions 8 1 RMS Root Mean Squared Value The RMS value is the most commonly used and useful means of specifying the value of both AC voltage and current The RMS value of an AC waveform indicates the level of power that is available from that waveform and is equivalent DC at the same voltage This is one of the most important attributes of any AC source The calculation of an RMS value can best be described by considering an AC current waveform and its associated heating effect such as that shown in Figure 21 The current Amp is considered to be flowing through a resistance th
22. tektronix com power analyzer 11 Application Note e img Mowewe Taw tur WHO OO ge Nowe Aromi Upined Bss brosse Nirtarah J Defautt Applicationa r a hats Funes Aano a gt erap A berae _ or whe Voltage Chasne non a9 busts ta gamay fee E Lets t Curera Chennai on ee th i m Panam Vern y om bute Keegy act peewee Jy O j motes Tt CO army a a J mote J lowe Agt e gt Figure 19 Full compliance standby power test 7 Standby Power Compliance Tests The power consumed by power supply while they are not loaded is called standby power The standby power is trivial when considered for individual power supplies but when equated as a whole over a longer period of time and considering the number of power supplies plugged in to sockets all the time becomes a significant waste of energy Many programs are already in place to reduce standby power including ENERGY STAR and the EU Eco Directive The scope of these programs continues to grow and the level of standby power in Watts necessary to achieve compliance steadily falls PWRVIEW software offers engineers a straight forward and accurate tool to conduct a full compliance standby power test and get to the market faster and cheaper Figure 19 shows a snapshot of a full compliance standby test in action For more details on standby power and full compliance stand by test please refer to Standby Power app no
23. test making connections as demonstrated earlier m Connect both PA s to the computer via USB Ethernet or GPIB and add them to PWRVIEW m Once added PWRVIEW will display two tabs for two Power Analyzers connected as shown in Figure 14 Power Measurements on AC DC Power Supplies Sme Arrt Upisi Aii fewer PANDORO PALODOROOM Rote sne ticieecy Configas ations 5 7 A Tir Cote oe 0e y O ooe y i p 3 gt gt 3 5 5 3 gt 5 3 J 5 gt TT Figure 15 Efficiency configuration O O wpet a lago 1 t i O O tpt a lapa 7 Rew aqeny Ada ed Reo spony Ata vp Erus Brih ep dess Bent dess Berdoa eee Ami 5 i ewer es re me uman p pps nn y MIDIR Figure 17 Waveform display Figure 18 Harmonic bar chart display m For calculating efficiency just click on the Configure radio m Once done click on the Measure tab on the top and then tab on the top ribbon click start on the Measure page m This will open a new tab for input and output selection as m The Measurement grid will start making efficiency shown in Figure 15 measurement based on the input and output wattage as m Once proper groups are selected for input and output seen in the Figure 16 just click on the radio button Enable Watts Efficiency m PWRVIEW can also be used to view waveforms and bar Measurements charts as shown in following Figure 17 and Figure 18 respectively www
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