Datasheet ADE7758 (Analog Devices) - 50

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ADE7758 Data Sheet
Step 5: Set the LENERGY bit, MASK[12] (0x18), to Logic 1 Step 9b: Calculate the values to be written to the xVAG registers to enable the interrupt signaling the end of the line cycle according to the following equation: accumulation. VAHR = EXPECTED Step 6: Set the test system for ITEST, VNOM, and unity power factor 4 × MC × I ×V × AccumTime TEST NOM VARCFDEN 1 (calibrate watt and VA simultaneously and first). × × 1000 × 3600 VARCFNUM VADIV Step 7: Read the FREQ (0x10) register if the line frequency is (64) unknown. ⎛ VAHR ⎞ Step 8: Reset the interrupt status register by reading EXPECTED 12 xVAG = −1 ×2 ⎜⎜ ⎟⎟ VAHR RSTATUS (0x1A). ⎝ MEASURED ⎠ Step 9: Read all six xWATTHR (0x01 to 0x03) and xVAHR Step 10: Write to xWG and xVAG. (0x07 to 0x09) energy registers after the LENERGY interrupt Step 11: Set the test system for ITEST, VNOM, and zero power and store the values. factor inductive to calibrate VAR gain. Step 9a: Calculate the values to be written to xWG registers Step 12: Repeat Step 7. according to the following equations: Step 13: Read the xVARHR (0x04 to 0x06) after the LENERGY WATTHR = EXPECTED interrupt and store the values. 4 × MC × I ×V × cos(θ)× AccumTime TEST NOM × (60) Step 14: Calculate the values to be written to the xVARG 1000 × 3600 registers (to adjust VARCF to the expected value). APCFDEN 1 × VARHR = EXPECTED APCFNUM WDIV 4 × MC × I ×V × ( sin θ)× AccumTime TEST NOM × where AccumTime is (65) 1000 × 3600 [ LINECYC : 15 ] 0 VARCFDEN 1 (61) × 2 × Line Frequency × No.of Phases Selected VARCFNUM VARDIV where: ⎛ VARHR ⎞ EXPECTED 12 xVARG = −1 × 2 ⎜⎜ ⎟⎟ MC is the meter constant. ⎝ VARHRMEASURED ⎠ θ is the angle between the current and voltage. Step 15: Write to xVARG. Line Frequency is known or calculated from the FREQ[11:0] Step 16: Calculate the Wh/LSB, VARh/LSB, and VAh/LSB register. With the FREQ[11:0] register configured for line period constants. measurements, the line frequency is calculated with Equation 62. Wh I ×V ×cos(θ)× AccumTime TEST NOM 1 = (66) Line Frequency = (62) LSB 3600 × xWATTHR 6 - [11 FREQ : 0]×9.6×10 VAh I ×V × AccumTime No. of Phases Selected is the number of ZXSEL bits set to Logic 1 TEST NOM = (67) LSB 3600 × xVAHR in LCYCMODE (0x17). VARh I ×V × ( sin θ) Then, xWG is calculated as × AccumTime TEST NOM = (68) 3600 × ⎛ LSB xVARHR WATTHR ⎞ EXPECTED 12 xWG = −1 × 2 ⎜⎜ ⎟⎟ (63) ⎝ WATTHR
Example: Watt Gain Calibration Using Line Accumulation
MEASURED ⎠ This example shows only Phase A watt calibration. The steps outlined in the Gain Calibration Using Line Accumulation section show how to calibrate watt, VA, and VAR. All three phases can be calibrated simultaneously because there are nine energy registers. For this example, ITEST = 10 A, VNOM = 220 V, Power Factor = 1, Frequency = 50 Hz, LINECYC (0x1C) is set to 0x800, and MC = 3200 imp/kWhr. Rev. E | Page 50 of 72 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS GENERAL DESCRIPTION SPECIFICATIONS TIMING CHARACTERISTICS TIMING DIAGRAMS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TERMINOLOGY TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS THEORY OF OPERATION ANTIALIASING FILTER ANALOG INPUTS CURRENT CHANNEL ADC Current Channel Sampling di/dt CURRENT SENSOR AND DIGITAL INTEGRATOR PEAK CURRENT DETECTION Peak Current Detection Using the PEAK Register OVERCURRENT DETECTION INTERRUPT VOLTAGE CHANNEL ADC Voltage Channel Sampling ZERO-CROSSING DETECTION Zero-Crossing Timeout PHASE COMPENSATION PERIOD MEASUREMENT LINE VOLTAGE SAG DETECTION SAG LEVEL SET PEAK VOLTAGE DETECTION Peak Voltage Detection Using the VPEAK Register Overvoltage Detection Interrupt PHASE SEQUENCE DETECTION POWER-SUPPLY MONITOR REFERENCE CIRCUIT TEMPERATURE MEASUREMENT ROOT MEAN SQUARE MEASUREMENT Current RMS Calculation Current RMS Offset Compensation Voltage Channel RMS Calculation Voltage RMS Offset Compensation Voltage RMS Gain Adjust ACTIVE POWER CALCULATION Active Power Gain Calibration Active Power Offset Calibration Sign of Active Power Calculation No-Load Threshold Active Energy Calculation Integration Time Under Steady Load Energy Accumulation Mode Active Power Frequency Output Line Cycle Active Energy Accumulation Mode REACTIVE POWER CALCULATION Reactive Power Gain Calibration Reactive Power Offset Calibration Sign of Reactive Power Calculation Reactive Energy Calculation Integration Time Under Steady Load Energy Accumulation Mode Reactive Power Frequency Output Line Cycle Reactive Energy Accumulation Mode APPARENT POWER CALCULATION Apparent Power Gain Calibration Apparent Power Offset Calibration Apparent Energy Calculation Integration Time Under Steady Load Energy Accumulation Mode Apparent Power Frequency Output Line Cycle Apparent Energy Accumulation Mode ENERGY REGISTERS SCALING WAVEFORM SAMPLING MODE CALIBRATION Calibration Using Pulse Output Gain Calibration Using Pulse Output Example: Watt Gain Calibration of Phase A Using Pulse Output Phase Calibration Using Pulse Output Example: Phase Calibration of Phase A Using Pulse Output Power Offset Calibration Using Pulse Output Example: Offset Calibration of Phase A Using Pulse Output Calibration Using Line Accumulation Gain Calibration Using Line Accumulation Example: Watt Gain Calibration Using Line Accumulation Phase Calibration Using Line Accumulation Example: Phase Calibration Using Line Accumulation Power Offset Calibration Using Line Accumulation Example: Power Offset Calibration Using Line Accumulation Calibration of IRMS and VRMS Offset Example: Calibration of RMS Offsets CHECKSUM REGISTER INTERRUPTS USING THE INTERRUPTS WITH AN MCU INTERRUPT TIMING SERIAL INTERFACE SERIAL WRITE OPERATION SERIAL READ OPERATION ACCESSING THE ON-CHIP REGISTERS REGISTERS COMMUNICATIONS REGISTER OPERATIONAL MODE REGISTER (0x13) MEASUREMENT MODE REGISTER (0x14) WAVEFORM MODE REGISTER (0x15) COMPUTATIONAL MODE REGISTER (0x16) LINE CYCLE ACCUMULATION MODE REGISTER (0x17) INTERRUPT MASK REGISTER (0x18) INTERRUPT STATUS REGISTER (0x19)/RESET INTERRUPT STATUS REGISTER (0x1A) OUTLINE DIMENSIONS ORDERING GUIDE