Energy & Power Meters History by O3L09H

VIEWS: 39 PAGES: 14

									Energy & Power Meters
History &
Measurement Principle


                        Ben Kemink
      History and Types of Energy & Power Meters

                                                  1960’s      70’s           80’s        90’s

                   Current Transformer Input
                             Electro-dynamic                  (50 - 60 Hz)
                             Wattmeter
    Traditional
    Stable Loads
                             Torque Balanced                APR2
                             Type
                             Time Division Multiplier                 2885 (50 - 400 Hz)
                             Type                                            2533 (DC, 10Hz - 20kHz)
                             Digital Display Power Meters


                   Current Shunt Input                                                2532(DC,20Hz-400kHz))
    Traditional             Digital Sampling                                        WT1600 (DC,0.5Hz-1MHz))
                            Power Meters
    Stable Loads                                                                     WT230 (DC,0.5Hz-100kHz))
                                                                                     WT3000 (DC, 0.1Hz-1MHz)

    New Generation            Single Shot Power Meter                                 PZ4000 DC – 2MHz
    Un-Stable Loads
    QUALITY
              INNOVATION
                           FORESIGHT
2
                       Thermocouple WATT-meter

       The thermocouple generates a DC-voltage proportionally to
       the temperature difference of the junction and the
       reference point.

        A moving coil instrument is used to indicate the result.


        This instrument can be used to measure both DC and AC.
        Frequency bandwidth Current: up to approx. 10 MHz
                              Voltage: up to approx. 100 kHz




       The heating-wire is very thin and easily burned out by an
       over-current.

    QUALITY
              INNOVATION
                           FORESIGHT
3
                            Electro-Dynamic WATT-meter




         If fixed coils are representing the load-current and the
         moving coil the voltage-representative current, we are
         directly measuring electric power.



         This instrument can measure DC and AC.

         Frequency bandwidth Current: up to approx. 1000 Hz
                             Voltage: up to approx. 150 Hz




    QUALITY
              INNOVATION
                           FORESIGHT
4
                           Electro-Dynamic WATT-meter




    QUALITY
              INNOVATION
                           FORESIGHT
5
        Thermal Watt Meter versus Electro-dynamic Meter




       i




       i




    QUALITY
              INNOVATION
                           FORESIGHT
6
                  Analogue Measurement, Digital Readout


         Voltage       u(t)                         Analogue          Low pass
         input circuit                              multiplier        filter

                                                          X
         Current             i(t)
                                                     p(t)=u(t).i(t)
                                                                                    T
                                                                                   1
         input circuit                                                   Paverage   p(t).dt
                                                                                   T0

                                                   RMS circuit                                  To A/D
                                                                                                converter


                                                  MEAN circuit


                                                   RMS circuit


                                         T
                                     1
              Average power           u (t ).i(t ).dt
                                     T0
    QUALITY
              INNOVATION
                           FORESIGHT
7
                       Analogue calculation, Digital Readout
                                       Yokogawa 2533E




    QUALITY
              INNOVATION
                           FORESIGHT
8
                   Time-division multiplication principle




    QUALITY
              INNOVATION
                           FORESIGHT
9
                                    Today: WT-Family en PZ

                                                      Sampled
                                                      Instantaneous
                                                      voltage value
               Voltage                                     U(n)
                                 u(t)
               input                          A/D
               circuit
                                                      Sampled
                                                      Instantaneous    DSP         To next
                                                      current                      stage
                                                          I(n)
               Current           i(t)
               input                         A/D
               circuit

                                                                      Digital
                                                                      Signal
                                  1 N
                    Active Power   U( n ) .I( n )                   Processing
                                  N n 1

     QUALITY
               INNOVATION
                            FORESIGHT
10
       Digital Calculations and Display: WT-Family and PZ




     QUALITY
               INNOVATION
                            FORESIGHT
11
                             Example of true digital type
                                        Yokogawa 2531A




     QUALITY
               INNOVATION
                            FORESIGHT
12
                                        DSP versus CPU


                                                            Urms
         Measurement via DSP operation                      Irms
                                                            W
          32-bit floating point operation                  VA
          80ns for WT2000                                  Var
            (250ms display update)                          PF
          50ns for WT1000                                  
           (100ms display update)

                                                          Range conversion
         Measurement via CPU                              
         computation                                      Scaling




     QUALITY
               INNOVATION
                            FORESIGHT
13
                                 Energy & Power Measurement Trend


                                               1950s                            1980s                Present time               Near future

               Requirement           Stability / Repeatability      Accuracy / Bandwidth        Real time / Analysis         Efficiency / Control

                Background        Boom of house appliances               Boom of Inverter       Harmonics / Flicker           Ecology / Energy

               Object / Target       Commercial frequency                   Static power       Static power / Analysis        Transient power

                  Sensing                       Coil                        CT, DC/CT           Non inductive shunt      High freq . probe/sensor

                  Method                     Moving coil                Analog circuit or IC    Digital circuit or IC            Digital IC

                                                                                                                         V        A-D
                                                           Fixed    V                            V          A-D                           DSP
                                                           coils                         LPF                             A        A-D
                                                         Moving
                                                                    A                            A          A-D
                                                         coil
                                                                                                                                  A-D
                                                                                                                                          DSP
                                                                                                                                  A-D
                                                            Fixed
                                                            coil          A-D                         DSP         CPU
                                  Pointer                                               CPU
                                  of meter             Moving                                                                    CPU       CRT
                                                       coil
                                                            Fixed
                                                                                                     MEMORY
                                                            coil                                                               MEMORY

                Principle or           Electrodynamometer           Feedback time division              DSP                         DSP
                                                                      multiplier system
                Acquisition                                                                      Digital multiplier           Sampling A/D C
                                                                        Feedback pulse width
                  method                                                                         Sampling A/D C
                                                                            modulation
                                                                                   /D
                                                                         Counting A C          Real time FFT analysis

                  Theme                       Accuracy                       Response           Isolation / Software         Probing/ Calibration

     QUALITY
                INNOVATION
                                 FORESIGHT
14

								
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