SLAA517F May   2012  – August 2021 MSP430F6720A , MSP430F6720A , MSP430F6721A , MSP430F6721A , MSP430F6723A , MSP430F6723A , MSP430F6724A , MSP430F6724A , MSP430F6725A , MSP430F6725A , MSP430F6726A , MSP430F6726A , MSP430F6730A , MSP430F6730A , MSP430F6731A , MSP430F6731A , MSP430F6733A , MSP430F6733A , MSP430F6734A , MSP430F6734A , MSP430F6735A , MSP430F6735A , MSP430F6736 , MSP430F6736 , MSP430F6736A , MSP430F6736A

 

  1.   Trademarks
  2. 1Introduction
  3. 2System Diagrams
  4. 3Hardware Implementation
    1. 3.1 Power Supply
      1. 3.1.1 Resistor Capacitor (RC) Power Supply
    2. 3.2 Analog Inputs
      1. 3.2.1 Voltage Inputs
      2. 3.2.2 Current Inputs
  5. 4Software Implementation
    1. 4.1 Peripherals Setup
      1. 4.1.1 SD24 Setup
    2. 4.2 Foreground Process
      1. 4.2.1 Formulas
        1. 4.2.1.1 Voltage and Current
        2. 4.2.1.2 Power and Energy
    3. 4.3 Background Process
      1. 4.3.1 Voltage and Current Signals
      2. 4.3.2 Phase Compensation
      3. 4.3.3 Frequency Measurement and Cycle Tracking
      4. 4.3.4 LED Pulse Generation
  6. 5Energy Meter Demo
    1. 5.1 EVM Overview
      1. 5.1.1 Connections to the Test Setup for AC Voltages
      2. 5.1.2 Power Supply Options and Jumper Settings
    2. 5.2 Loading the Example Code
      1. 5.2.1 Opening the Project
  7. 6Results and Calibration
    1. 6.1 Viewing Results
    2. 6.2 Calibrating the Meter
      1. 6.2.1 Gain Correction
      2. 6.2.2 Phase Correction
      3. 6.2.3 Metrology Results
  8. 7References
  9. 8Schematics
  10. 9Revision History

6.2.3 Metrology Results

In this discussion, metrology results are shown. Current transformers have been used, however, the code supports shunt resistors as well. Figure 6-6 shows the results for current that is varied from 50 mA to 100 A exhibiting a 2000:1 dynamic range. Table 6-1 shows the values for the error at room temperature.

Table 6-1 Energy Measurement Accuracy With Error in (%) (Calibrated at 230 V, 15 A, 50 Hz)
Current
(Amps)		 0° 60° -60°
0.05 -0.045 0.058 -0.07
0.1 -0.019 0.083 -0.07
0.25 -0.019 0.0575 -0.0575
0.5 0.006 0.083 -0.045
1 0.0147 0.0663 -0.0617
2 -0.007 0.058 -0.07
5 0.0043 0.022 -0.019
10 -0.007 -0.024 0.003
20 -0.015 -0.0533 0.0493
30 0.0003 -0.079 0.0747
40 -0.0067 -0.096 0.07
50 0.011 -0.106 0.1023
60 0.0006 -0.099 0.1203
70 0.0167 -0.096 0.1187
80 0.0263 -0.098 0.143
90 0.0367 -0.096 0.1563
100 0.0387 -0.0943 0.16
GUID-7392FE3E-3957-4267-AB80-058AB49ABD0D-low.png Figure 6-6 Measurement Accuracy Across Current