Power Transducer User’s Guide - Signal Conditioners

1 Power TransducerUser s GuideVolume 1 1991 Moore Industries-International, Inc. Power Transducer user 's GuideVolume 1 Applying Power TransducersNotes 1991 Moore Industries-International, Monitor Power ? .. Definitions .. Concepts of AC Power .. 5IV. Common AC Power Systems .. Common AC Power Systems .. 15VI. Taking Watt and VAR Measurements .. 19 VII. Glossary .. 25 VIII. Reference Charts and InformationA. Transducer output calculations .. 33B. Full-load motor currents .. 35C. Nameplate voltage ratings of standard induction motors .. 36D. Nominal system voltages.

2 37IX. Power Transducers available from Moore Industries .. 39 PagePage 40 NotesSpecifications subject to change 1991 Moore Industries-International, Why Monitor Power ?With ac Power consumption and measurement drawing ever-moreattention throughout the process industries, an understanding ofbasic ac parameters becomes increasingly simple reference Guide uses illustrations and simple defini-tions to explain the basics of ac Power and its uses in the processindustries. This comparison shows the relationship between theterms used in measuring electrical current and standard processflow concepts:Electrical TermFlow TermCurrentFlowVoltagePressureResistance Pressure DropKeeping this simple analogy in mind should help you understandand apply the basic principles needed to use Power help in controlling your ac Power usage, or ordering powertransducers, please call your local representative.

3 In addition, ourhelpful Sales Engineers are available during business hours. Pleaseconsult the back of this booklet for the phone number of the officenearest Nameplate Voltage Ratings of StandardInduction MotorsNominal System VoltageNameplate VoltageSingle-Phase Motors:120 .. 115240 .. 230 Three-Phase Motors:208 .. 200240 .. 230480 .. 460600 .. 5752400 .. 23004160 .. 40004800 .. 46006900 .. 660013800 .. 13200 Data taken from IEEE Std. 141-1976 Reference Charts and InformationPage 36 Page 1 1991 Moore Industries-International, Beginning DefinitionsPrior to reading further in this booklet, please familiarize yourselfwith these basic terms of electricity and ac Power The basic unit used to measure current, often abbrevi-ated as amp or A.

4 It equals a unit of electrical current or the rateof flow of electrons. One volt across one ohm of resistance resultsin current flow of one The movement or flow of electrons through a conductor,represented by the letter symbol I. Voltage The force causing current to flow through a conductor,represented by the letter symbol E. The unit of measure is thevolt, or V. One volt equals the force required to produce a currentflow of one ampere through a resistance of one The portion of a Transducer which senses one input eachof voltage and As current flows through a conductor it encountersforce which blocks its path.

5 The force consists of passive compo-nents (resistance) and reactive components (inductive andcapacitive reactance.) Impedance is measured in ohms and thesymbol is Z. Resistance Component of impedance due to passive elements ofthe load. Resistance is represented by the letter symbol R. Oneunit of resistance is known as an Component of impedance due to active elements ofthe load. Symbol is X. Ohm A single ohm equals the amount of impedance that will limitthe current in a conductor to one ampere when one volt is applied tothe conductor, represented by the Greek letter . Frequency The number of times that the variations of an alternat-ing current represented by the sine waveform are repeated duringone second of time, expressed in hertz or Hz.

6 One hertz equalsone cycle per Transducer CalibrationsIf we use the same transducers and transformers as in example 1,and say that the customer has a meter that is already scaled for 0-60,000 watts, we have to work in reverse to determine the appropri-ate calibration point for the Transducer . We would take the 60,000watts and divide this by the transformer ratios:In order to get 60,000 watts full scale with the customer s transform-ers, we would have to calibrate the Transducer to 375 watts 34 Page 3 Reference Charts and Information60,00048012010052 ELEMENTS375 WATTS/ELEMENTX=X 1991 Moore Industries-International, Beginning DefinitionsPrior to reading further in this booklet, please familiarize yourselfwith these basic terms of electricity and ac Power The basic unit used to measure current, often abbrevi-ated as amp or A.

7 It equals a unit of electrical current or the rateof flow of electrons. One volt across one ohm of resistance resultsin current flow of one The movement or flow of electrons through a conductor,represented by the letter symbol I. Voltage The force causing current to flow through a conductor,represented by the letter symbol E. The unit of measure is thevolt, or V. One volt equals the force required to produce a currentflow of one ampere through a resistance of one The portion of a Transducer which senses one input eachof voltage and As current flows through a conductor it encountersforce which blocks its path.

8 The force consists of passive compo-nents (resistance) and reactive components (inductive andcapacitive reactance.) Impedance is measured in ohms and thesymbol is Z. Resistance Component of impedance due to passive elements ofthe load. Resistance is represented by the letter symbol R. Oneunit of resistance is known as an Component of impedance due to active elements ofthe load. Symbol is X. Ohm A single ohm equals the amount of impedance that will limitthe current in a conductor to one ampere when one volt is applied tothe conductor, represented by the Greek letter . Frequency The number of times that the variations of an alternat-ing current represented by the sine waveform are repeated duringone second of time, expressed in hertz or Hz.

9 One hertz equalsone cycle per Transducer CalibrationsIf we use the same transducers and transformers as in example 1,and say that the customer has a meter that is already scaled for 0-60,000 watts, we have to work in reverse to determine the appropri-ate calibration point for the Transducer . We would take the 60,000watts and divide this by the transformer ratios:In order to get 60,000 watts full scale with the customer s transform-ers, we would have to calibrate the Transducer to 375 watts 34 Page 3 Reference Charts and Information60,00048012010052 ELEMENTS375 WATTS/ELEMENTX=X 1991 Moore Industries-International, Basic Concepts of Ac PowerThis material should give non-electrical engineers a feel for some ofthe basic characteristics of electrical systems.

10 Ideally, this informa-tion will help you implement and work with an energy monitoring andmanagement Direct Current CircuitIn a direct current circuit voltage and current are constant. Thereare only resistive loads. The relationship between voltage, currentand resistance is E = IR. Power is defined P = EI = I2R. A watt isone volt times one amp. 1W = (1V) (1A). Power Alternating Current CircuitAlternating current is created by rotating a coil of conductive wirethrough a magnetic field (Drawing 1). Drawing 2 represents theresults of the rotating action through the magnetic field.