ASHRAE 41 11-2014 Standard Methods for Power Measurement.pdf

1、ANSI/ASHRAE Standard 41.11-2014Standard Methods forPower MeasurementApproved by the ASHRAE Standards Committee on June 28, 2014; by the ASHRAE Board of Directors on July 2, 2014; and by theAmerican National Standards Institute on July 3, 2014.ASHRAE Standards are scheduled to be updated on a five-ye

2、ar cycle; the date following the standard number is the year ofASHRAE Board of Directors approval. The latest edition of an ASHRAE Standard may be purchased on the ASHRAE website(www.ashrae.org) or from ASHRAE Customer Service, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305. E-mail:ordersashrae.org.

3、 Fax: 678-539-2129. Telephone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US andCanada). For reprint permission, go to www.ashrae.org/permissions. 2014 ASHRAE ISSN 1041-2336SPECIAL NOTEThis American National Standard (ANS) is a national voluntary consensus standard developed

4、 under the auspices of ASHRAE.Consensus is defined by the American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved thisstandard as an ANS, as “substantial agreement reached by directly and materially affected interest categories. This signifies the concurrence

5、of more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that aneffort be made toward their resolution.” Compliance with this standard is voluntary until and unless a legal jurisdiction makes compliancemandatory through legisl

6、ation.ASHRAE obtains consensus through participation of its national and international members, associated societies, and public review.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The ProjectCommittee Chair and Vice-Chair must

7、be members of ASHRAE; while other committee members may or may not be ASHRAE members, allmust be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all ProjectCommittees.The Manager of Standards of ASHRAE should be contacted for:a. i

8、nterpretation of the contents of this Standard,b. participation in the next review of the Standard,c. offering constructive criticism for improving the Standard, ord. permission to reprint portions of the Standard.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for the

9、benefit of the public in light of available information andaccepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components,or systems tested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that an

10、y tests conducted under itsStandards or Guidelines will be nonhazardous or free from risk.ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for ratingpurposes,bysuggestingsafeprac

11、ticesindesigningandinstallingequipment,byprovidingproperdefinitionsofthisequipment,andbyprovidingother information that may serve to guide the industry.The creation of ASHRAE Standards and Guidelines is determined by the need for them,and conformance to them is completely voluntary.In referring to t

12、his Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied,that the product has been approved by ASHRAE.ASHRAE Standing Standard Project Committee 41CognizantTC: 1.2, Instruments and MeasurementsSPLS Liaison: John F. DunlapMark Kedziers

13、ki, Chair * B. Terry Beck* John P. Scott*Richard L. Hall, Sub. 41.11 Chair* Patrick Collins* Frank J. Spevak *James L. Douglas, Secretary* Lloyd Le* Russell Tharp*Kevin Amende* Alexander Leyderman* Michael Wegenka*Erik Anderson* Kevin Peck* Charles Wright*Shane Angle* Armin Hauer Eric GrahamRick Hei

14、den John Neel John TolbertMike Todd Michael Wegenka Scott Wujek*Denotes members of voting status when the document was approved for publicationASHRAE STANDARDS COMMITTEE 20132014William F. Walter, Chair David R. Conover Malcolm D. KnightRichard L. Hall, Vice-Chair John F. Dunlap Rick A. LarsonKarim

15、Amrane James W. Earley, Jr. Mark P. ModeraJoseph R. Anderson Steven J. Emmerich Cyrus H. NasseriJames Dale Aswegan Julie M. Ferguson Janice C. PetersonCharles S. Barnaby Krishnan Gowri Heather L. PlattSteven F. Bruning Cecily M. Grzywacz Douglas T. ReindlJohn A. Clark Rita M. Harrold Julia A. Keen,

16、BOD ExOWaller S. Clements Adam W. Hinge Thomas E. Werkema, Jr., CODebra H. KennoyStephanie C. Reiniche, Manager of StandardsCONTENTSANSI/ASHRAE Standard 41.11-2014,Standard Methods for Power MeasurementSECTION PAGEForeword .21 Purpose.22 Scope23 Definitions .24 Classifications .45 Requirements46 Ins

17、truments .47 Test Methods 58 Uncertainty Calculations .59 Test Report .610 Normative References.6Informative Annex A: Bibliography 7Informative Annex B: Power Measurement Basics .8Informative Annex C: Methods for Uncertainty14Informative Annex D: An Uncertainty Analysis Example for the Input and Out

18、put Power of aVariable-Frequency Drive15Informative Annex E: Examples of Power Derived from the First Law of Thermodynamics .22NOTEApproved addenda, errata, or interpretations for this standard can be downloaded free of charge from the ASHRAEWeb site at www.ashrae.org/technology. 2014 ASHRAE1791 Tul

19、lie Circle NE Atlanta, GA 30329 www.ashrae.org All rights reserved.ASHRAE is a registered trademark of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ANSI is a registered trademark of the American National Standards Institute.2 ANSI/ASHRAE Standard 41.11-2014(This

20、 foreword is not part of this standard. It is merelyinformative and does not contain requirements necessaryfor conformance to the standard. It has not been pro-cessed according to the ANSI requirements for a standardand may contain material that has not been subject topublic review or a consensus pr

21、ocess. Unresolved objec-tors on informative material are not offered the right toappeal at ASHRAE or ANSI.)FOREWORDThe scope of ASHRAE Standard 41.11 includes electricaland nonelectrical power measurements for heating, ventilat-ing, air-conditioning, and refrigerating (HVAC the currentis measured ac

22、ross the secondary winding. Note: an open cir-cuit across the secondary winding shall be avoided.current transducer: a current transducer (sensor) is a devicethat detects electrical current (alternating current AC ordirect current DC) in a conductor and generates a signalproportional to it. The comb

23、inations of sensed current and theoutput signal are as follows:AC current input withanalog output, which duplicates the wave shape of thesensed current;bipolar output, which duplicates the wave shape of thesensed current; orunipolar output, which is proportional to the average orRMS value of the sen

24、sed current.DC current input withunipolar output, which duplicates the wave shape of thesensed current; ordigital output, which switches when the sensed currentexceeds a certain threshold.energy: capability to do work. Forms include chemical, elec-trical, mechanical, and thermal. Energy may be eithe

25、r storedor transient and can be transformed from one form intoanother. Compare to power. In electricity, expressed as watt-hour or sometimes joule (joule = watt-second).error: the difference between the true value of the quantitymeasured and the observed value. All errors in experimentaldata can be

26、classified as one of two types: systematic (fixed)errors or random (precision) errors. The terms accuracy andprecision are often used to distinguish between systematicand random errors. A measurement with small systematicerrors is said to be unbiased. A measurement with small ran-dom errors is said

27、to have high precision. A measurement thatis unbiased and precise is said to be accurate.fixed error: same as systematic error.ANSI/ASHRAE Standard 41.11-2014 3harmonics: currents or voltages with frequencies that areinteger multiples of the fundamental power frequency.input: something put into a sy

28、stem or expended in its opera-tion to achieve output or a result; for example, energy, work,or power used to drive a machine or current, electromotiveforce, or power supplied to an electric circuit, network, ordevice.linear: sinusoidal waveform, (for example, a constant-speeddrive).load: A device or

29、 the resistance of a device to which power isdelivered; for example, a motor is typically the load of a vari-able-speed drive.nonlinear: nonsinusoidal waveform, (for example, a variable-speed drive).phase transformer: see real power factor.potential (electrical): a scalar quantity equivalent to a jo

30、uleper coulomb, measured in volts (V).potential transformer: an instrument transformer whose pri-mary winding is connected in parallel with a circuit in whichthe voltage is to be measured or controlled. Also known asvoltage transformer. Note: a short circuit across the secondarywinding cannot be tol

31、erated.precision error: same as random error.power: rate of doing work, or energy divided by time. Theunit of power is the watt (W), which is equal to one joule persecond. Other units of power include ergs per second (erg/s),horsepower (hp), and foot-pounds per minute. Compare toenergy.power, active

32、 : the product of the voltage across a branchof an alternating-current circuit and the component of theelectric current that is in phase with the voltage.power, apparent: the product of the root-mean-squarevoltage and the root-mean-square current delivered in analternating-current circuit, no accoun

33、t being taken of thephase difference between voltage and current, measuredin volt-amperes.power, nonelectrical: types of nonelectrical power,including shaft power, power derived from the first lawof thermodynamics, and fluid power output from a pump.power, reactive: also called imaginary power or “w

34、at-tless” power. Reactive loads, such as inductors andcapacitors, dissipate zero power, yet the fact that theydrop voltage and draw current gives the deceptiveimpression that they actually dissipate power. This“phantom power” is called reactive power and is mea-sured in volt-amps-reactive.power, rea

35、l: also known as active power, the product ofthe voltage across a branch of an alternating-current cir-cuit and the component of the electric current that is inphase with the voltage, measured in watts (W).power factor: the ratio of the real power flowing to the load tothe apparent power in the circ

36、uit, expressed as a dimension-less number between 0 and 1, or expressed as a percentage(e.g., 50% PF).power factor, displacement: the cosine of the anglebetween the voltage and the current zero crossings () forlinear AC loads (compare to power factor).power factor, real: the ratio of the average (or

37、 active)power to the apparent power (root-mean-square voltagetimes root-mean-square current) of an alternating-currentcircuit. Also known as phase factor.random error: an error which causes readings to take randomvalues on either side of a mean value. The random error isquantified based on how well

38、an instrument can reproducesubsequent readings for an unchanging input. Random errorscannot be corrected through calibration.reactive power: see power, reactive.real power: see power, real.root-mean-square (RMS): a statistical measure of the magni-tude of a varying quantity. The RMS value of a set o

39、f values(or a continuous-time waveform) is the square root of thearithmetic mean (average) of the squares of the original val-ues (or the square of the function that defines the continuouswaveform).shaft speed: the rate at which a motor shaft turns, measured inrevolutions per second (r/s) or revolut

40、ions per minute (rpm).systematic error: an error that persists and cannot be consid-ered as due entirely to chance. Systematic error can be cor-rected through calibration.torque: the moment of a force; the measure of a forces ten-dency to produce torsion and rotation about an axis, equal tothe vecto

41、r product of the radius vector from the axis of rota-tion to the point of application of the force and the force vec-tor, measured in Newton-meters (Nm).true RMS instrument: unlike other instruments that deter-mine the root-mean-square value of an alternating voltage orcurrent only if the waveform s

42、hape is perfectly sinusoidal, atrue RMS instrument determines the correct value of anywaveform by computing the square-root of the average ofmany squared values sampled along the curve.uncertainty: an estimated value for the error in a measure-ment, which may be the result of both systematic and ran

43、domerror. Because only random errors can be treated by statisticalmethods, and only systematic errors can be corrected throughcalibration, uncertainty computed using this standard wouldresult from random errors.unit under test (UUT): the system or component under test,including all power-consuming c

44、ontrol elements and accesso-ries.volt-amps-reactive: the units for reactive power (see power,reactive).variable-speed drive (VSD): describes equipment used tocontrol the speed of machinery. Compare to constant-speeddrives. Examples: using a VSD to modulate assembly linespeed or to vary the drive spe

45、ed for pumps or fans.volt-ampere: the unit used for the apparent power (see power,apparent) in an electrical circuit, equal to the product of root-mean-square voltage and RMS current.voltage transformer: see potential transformer.4 ANSI/ASHRAE Standard 41.11-20144. CLASSIFICATIONS4.1 Electrical Powe

46、r Measurement Application. Electricalpower measurements that are within the scope of this standardare classified as one of the following two types.4.1.1 Laboratory Application (Informative). Power mea-surements under laboratory conditions include, but are notlimited to, tests to determine product ra

47、tings and engineeringdevelopment tests. Laboratory power measurements useinstruments that tend to be more accurate than the instrumentsused for field measurements.4.1.2 Field Application (Informative). Power measure-ments under field conditions include, but are not limited to,tests to determine inst

48、alled product electrical consumption.Field power measurements use instruments that tend to beless accurate than the instruments used for laboratory mea-surements.4.2 Electrical Load Type. Electrical load configurations forelectrical power measurement are classified as one of the fol-lowing two types

49、.4.2.1 Linear Loads (Sinusoidal or DC Waveforms). Lin-ear loads contain no power electronic switching devices inter-posed between the power source and the load to alter thevoltage or current waveforms presented to the load.Linear alternating current (AC) drives use AC utilitypower or synchronous AC generators. Examples of linear ACdrives include constant-speed drives (CSDs) and motor start-ers used in conjunction with induction motors that incorpo-rate contactors or relays to connect the motor to the powersource. These include across-the-line, star-delta, part-wind-ing