3 Ph Energy Meter Reference
Design
Index
1. Introduction
a. 3 Ph Meter Specification
b. 3 Ph Energy Meter Block Diagram
c.
The Meter Overview
2. H/W implementation
a. Block Diagram
b. Power Supply
c.
Communication (RS232/RS485)
d. (i)Voltage Measurement, (ii)Current Measurements
e. Schematics
f.
PCB Layouts & Guidelines
3. S/W implementation
a. Microcontroller Flow Chart
i.
Peripheral usage
ii.
Display Parameters explanations
b. Functions used with explanation
c.
Calibration process
d. GUI Software explanation
e. V, Ct, PF calibration
f.
Energy, Phase Error calibration for R, Y & B phases
g. Tamper Flow Chart
h. Test Report Summary
4. Reference
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 1
1 Introduction
Abstract:
Excelpoint 3-Phase Energy Meter Reference Design is a fully functional energy meter with features such as voltage,
current, PF, four quadrant energy measurement, and active and reactive power calculation, Voltage Sag detection,
Phase interchange, Neutral missing, Zero Cross Detection. It uses Analog Devices ADE7878 is high accuracy, 3phase electrical energy measurement ICs with serial interfaces & 16-bit PIC24FJ128GA306 Microcontroller Unit
(MCU). It has communication interfaces like Isolated RS232 & RS485 base on industries leading iCoupler
®
Technology from Analog Devices.
The ADE7878 is high accuracy, 3-phase electrical energy measurement ICs with serial interfaces and three flexible
pulse outputs. The ADE7878 devices incorporate second-order sigma-delta (Σ-Δ) analog-to-digital converters (ADCs),
a digital integrator, reference circuitry; a fixed function digital signal processor (DSP) executes this signal processing.
The DSP program is stored in the internal ROM memory.
The ADE7878 are suitable for measuring active, reactive, and apparent energy in various 3-phase configurations,
such as wye or delta services, with both three and four wires. The reference design includes an electricity meter and
the companion PC software. Evaluation boards, schematics, bill of materials, and test results.
a. 3 Ph Meter Specification
Specification
Meter Accuracy
Meter Type
Voltage Operating Range
Current Operating Range Basic
Power Consumption
Mains Frequency
Energy Measurement
Tamper Detection
Activity Indicator
Communication - Optical Port
Remote Communication Port
Display
Display Modes
3 Ph Energy Meter Reference Design
Class 0.5
Whole Current / LT CT, 3 Ph 4 Wire
230/240 V AC (p-n)
10/40 A
As per IS 14697, <1W
50Hz
4 Quadrant Measurement of kWh, kVArh & kVAh
Missing Potential , Voltage unbalance. Voltage High/Low, Current Polarity
Reversal, Current Failure, Current Unbalance, Current High/Low, Low Power
Factor, Magnetic Influence
LED's For Calibration/Testing – kWh, kVArh
Optically Isolated Port As Per IEC62056-21
Isolated - RS232, RS485
Customised EM Segment LCD w Backlit
Auto Scroll Mode, Push Button Mode
www.excelpoint.com
Page 2
b. 3 Ph Energy Meter Block Diagram
c. The Meter Overview
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 3
2 H/W implementation
a.
Block Diagram
b.
Power Supply
SMPS-DUAL POWER SUPPLY
3PH Dual Power SMPS
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 4
c.
Communication
Isolated RS232 & RS485 communication is based on Analog Devices, Inc., iCoupler Technology. Combining high
speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding
performance characteristics superior to alternatives, such as Optocoupler devices.
By avoiding the use of LEDs and photodiodes, iCoupler devices remove the design difficulties commonly associated
with opto-couplers. The typical Optocoupler concerns regarding uncertain current transfer ratios, nonlinear transfer
functions, and temperature and lifetime effects are eliminated with the simple iCoupler digital interfaces and stable
performance characteristics.
The need for external drivers and other discrete components is eliminated with these iCoupler products. Furthermore,
iCoupler devices consume one-tenth to one-sixth of the power of Optocoupler at comparable signal data rates.
Isolated rating up to 5KVrms. All models operate with the supply voltage on either side ranging from 2.7 V to 5.5 V,
providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the
isolation barrier. Other features are
High isolation voltage: 5000 V rms
Low dynamic power consumption
Bidirectional communication
3 V to 5 V level translation
High temperature operation: 125°C
High common-mode transient immunity: >25 kV/μs
d.
i. Voltage Measurement
The voltage channel has three single-ended voltage inputs: VAP, VBP, and VCP. These single-ended voltage inputs
have a maximum input voltage of ±0.5 V with respect to VN. In addition, the maximum signal level on analog inputs for
VxP and VN is ±0.5 V with respect to AGND.
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 5
Above Figure presents the resistor divider normally used to measure the phase voltage in an ADE7878-based 3phase meter. The full-scale voltage (VFS) can be computed, that is, the rms of the sinusoidal voltage that determines
a full-scale sinusoid at the voltage channel ADC inputs.
Where R3 and R4 are the resistor divider components, and 0.5 V is the maximum allowed voltage at ADC inputs.
ii .Current Measurements
Above figure presents the current transformer input structure normally used on an ADE7878-based 3-phase meter.
Based on the current transformer characteristics and the burden resistors (R1 and R2), compute the full-scale current
(IFS), that is, the rms of the sinusoidal current that determines a full-scale sinusoid at the current channel ADC inputs
as follows:
Where: R1 and R2 are the burden resistors. CTRATIO is the current transformer input-to-output ratio, and 0.5 V is
the maximum allowed voltage at the ADC inputs.
Note that, for simplicity, Figure 3 does not show the ant aliasing filter that must be placed between the coil and the
ADE7878. A simple RC filter with a corner frequency of f0 > 2 kHz should be used.
Anti Aliasing Filter for Voltage & Current channels
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 6
Above Figure shows an analog low-pass filter (RC) on the input to the ADC. This filter is placed outside the ADE7878,
and its role is to prevent aliasing.
Aliasing means that frequency components in the input signal to the ADC, which are higher than half the sampling rate
of the ADC, appear in the sampled signal at a frequency below half the sampling rate.
Frequency components above half the sampling frequency (also known as the Nyquist frequency, that is, 512 kHz)
are imaged or folded back down below 512 kHz. This happens with all ADCs regardless of the architecture. In the
example shown, only frequencies near the sampling frequency, that is, 1.024 MHz, move into the band of interest for
metering, that is, 40 Hz to 2 kHz. To attenuate the high frequency (near 1.024 MHz) noise
e.
Schematics
Microcontroller Module
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 7
Display Module
IR Module
EEProm Module
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 8
RTC Module
RS232 Module
RS485 Module
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 9
Current Channel of ADE7878
Voltage Channel of ADE7878
ADE7878
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 10
CF Pulse LEDS
Bill Of Material
SYM_NAME
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
TH_2_BAT_790H
TH_2_BAT_790H
C0805
C0805
C0805
C0805
C0805
C0805
C0603
C0805
C0805
C0603
C0805
C0603
C0805
C0805
C0603
C0603
C0805
C0603
C0805
C0805
BCASE
C0603
C0805
C0805
C0805
C0805
C0603
C0805
C0805
C0603
C0805
C0805
C0805
C0805
3 Ph Energy Meter Reference Design
COMP_DEVICE_TYPE
BATTERY_TH_2_BAT_790H_BATTERY
BATTERY_TH_2_BAT_790H_CR2032
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0603_1UF_0603
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0603_1UF_0603
CAP_C0805_10UF_0805
CAP NP_C0603_100NF_0603
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0603_10UF_0603
CAP NP_C0603_100NF_0603
CAP_C0805_10UF_0805
CAP NP_C0603_100NF_0603
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP_BCASE_4.7UF_CASEB
CAP NP_C0603_100NF_0603
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0805_33NF_0805
CAP NP_C0603_1UF_0603
CAP NP_C0805_22NF_0805
CAP NP_C0805_22NF_0805
CAP NP_C0603_100NF_0603
CAP NP_C0805_22NF_0805
CAP NP_C0805_22NF_0805
CAP NP_C0805_18NF_0805
CAP NP_C0805_22NF_0805
www.excelpoint.com
COMP_VALUE
BATTERY
CR2032
33nF_0805
33nF_0805
33nF_0805
33nF_0805
33nF_0805
33nF_0805
1uF_0603
33nF_0805
33nF_0805
1uF_0603
4.7uF_0805
100nF_0603
33nF_0805
33nF_0805
4.7uF_0603
100nF_0603
4.7uF_0805
100nF_0603
33nF_0805
33nF_0805
4.7uf_CASEB
100nF_0603
33nF_0805
33nF_0805
33nF_0805
33nF_0805
1uF_0603
22nF_0805
22nF_0805
100nF_0603
33nF_0805
33nF_0805
33nF_0805
33nF_0805
COMP_
CLASS
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
REFDES
BT1
BT2
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
Page 11
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83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
C0805
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
BCASE
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
C0603
TH_28_78P74P_LCD_878
7C_120H
TH_2_LED_5MM_200H
TH_2_LED_5MM_200H
TH_2_LED_5MM_200H
TH_2_LED_5MM_200H
JUM_T2P1R_S
SOT23_118X063X050
SOT23_118X063X050
DO-35
DO-34
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
L1206
3 Ph Energy Meter Reference Design
CAP NP_C0805_22NF_0805
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP_C0603_0.1UF/10V_0603
CAP_C0603_0.1UF/10V_0603
CAP_C0603_0.1UF_6.3V_0603
CAP_C0603_0.1UF/10V_0603
CAP_C0603_0.1UF_0603
CAP_C0603_4.7UF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_10PF_0603
CAP NP_C0603_12PF_0603
CAP NP_C0603_12PF_0603
CAP NP_BCASE_4.7UF_CASEB
CAP NP_C0603_0.1UF_0603
CAP NP_C0603_10UF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_100NF_0603
CAP NP_C0603_47NF_0603
CAP NP_C0603_27PF_0603
CAP NP_C0603_0.1UF_0603
CAP NP_C0603_0.1UF_0603
CAP NP_C0603_27PF_0603
CAP NP_C0603_470NF_0603
CAP NP_C0603_470NF_0603
CAP NP_C0603_470NF_0603
CAP NP_C0603_470NF_0603
CAP NP_C0603_0.1UF_0603
CAP NP_C0603_0.1UF/20V_0603
CAP NP_C0603_0.1UF/20V_0603
CAP NP_C0603_0.1UF/20V_0603
CAP NP_C0603_100UF_16V_0603
CAP NP_C0603_1UF/16V_0603
CAP NP_C0603_1UF/16V_0603
33nF_0805
100nF_0603
100nF_0603
100nF_0603
100nF_0603
0.1uF/10V_0603
0.1uF/10V_0603
0.1uF_6.3V_0603
0.1uF/10V_0603
0.1uF_0603
4.7uF_0603
100nF_0603
100nF_0603
10pF_0603
12pF_0603
12pF_0603
4.7uF_CASEB
0.1uF_0603
10uF_0603
100nF_0603
100nF_0603
100nF_0603
47nF_0603
27pf_0603
0.1uF_0603
0.1uF_0603
27pf_0603
470nF_0603
470nF_0603
470nF_0603
470nF_0603
0.1uF_0603
0.1uF/20V_0603
0.1uF/20V_0603
0.1uF/20V_0603
100uF_16V_0603
1uF/16V_0603
1uF/16V_0603
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
C45
C46
C47
C48
C49
C50
C51
C52
C53
C54
C55
C56
C57
C58
C59
C60
C61
C62
C63
C64
C65
C66
C67
C68
C69
C70
C71
C72
CON29_1_TH_28_78P74P_LCD_8787C_
LED_TH_2_LED_5MM_200H_LED
LED_TH_2_LED_5MM_200H_LED
LED_TH_2_LED_5MM_200H_LED
LED_TH_2_LED_5MM_200H_LED
LED_JUM_T2P1R_S_BACK LIGHT
BAT54C/PLP_0_SOT23_118X063X050_
BAT54C/PLP_0_SOT23_118X063X050_
DIODE ZENER13_0_DO-35_3.6V
DIODE_1_DO-34_BAT85_SOD68
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1500
INDUCTOR AUDIO_L1206_BEED_1000_
INDUCTOR AUDIO_L1206_BEED_1000_
INDUCTOR AUDIO_L1206_BEED_1000_
LCD_8787C
LED
LED
LED
LED
BACK LIGHT
BAT54C
BAT54C
3.6V
BAT85_SOD68
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1500
BEED_1000_Ohms
BEED_1000_Ohms
BEED_1000_Ohms
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
CODISP1
D1
D2
D3
D5
D6
D7
D8
D10
D11
FB1
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB9
FB10
FB11
FB12
FB13
FB14
FB15
FB16
FB17
FB18
FB19
www.excelpoint.com
Page 12
104
105
106
107
L1206
L1206
L1206
L1206
108
109
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111
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118
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169
170
JUM_T2P1R_S
JUM_T2P1R_S
JUM_T2P1R_S
JUM_T2P1R_S
JUM_T2P1R_S
TH_6_100P_BERG_200H
TH_6_100P_BERG_200H
TH_6_100P_BERG_200H
TH_4_100P_BERG_200H
JUM_T2P1R_S
TH_3_100P
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
SOT23_118X063X050
R0805
R0805
R0805
R0603
R0603
R0603
R0603
R0603
R0805
R0603
R0805
R0805
R0603
R0603
R0805
R0805
R0603
R0805
R0402
R0805
R0603
R0805
R0805
R0603
R0603
R0805
R0805
R0805
R0805
R0402
R0603
R0805
R0805
R0805
R0805
R0603
R0805
R0805
R0805
R0805
R1206
R1206
R0805
3 Ph Energy Meter Reference Design
INDUCTOR AUDIO_L1206_BEED_1000_
INDUCTOR AUDIO_L1206_BEED_1000_
INDUCTOR AUDIO_L1206_BEED_1000_
INDUCTOR AUDIO_L1206_BEED_1000_
OPTO
ISOLATOR_0_JUM_T2P1R_S_OPT
CON2_JUM_T2P1R_S_CON2
CON2_JUM_T2P1R_S_CON2
CON2_JUM_T2P1R_S_CON2
CON2_JUM_T2P1R_S_CON2
CON6_0_TH_6_100P_BERG_200H_RJ11
CON6_TH_6_100P_BERG_200H_ICD CO
CON6_TH_6_100P_BERG_200H_PIC KI
CON4_TH_4_100P_BERG_200H_CON4
CON2_JUM_T2P1R_S_CON2
CON3_0_TH_3_100P_CON3
SXTA92_0_SOT23_118X063X050_SXTA
SXTA92_0_SOT23_118X063X050_SXTA
SXTA92_0_SOT23_118X063X050_SXTA
SVT7524_1_SOT23_118X063X050_BC8
SVT7524_0_SOT23_118X063X050_BC5
SXTA92_0_SOT23_118X063X050_SXTA
SXTA43_0_SOT23_118X063X050_SXTA
SXTA43_0_SOT23_118X063X050_SXTA
SVT7524_0_SOT23_118X063X050_BC8
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0805_22E_0805
RESISTOR_R0603_4.7K_0603
RESISTOR_R0603_4.7K_0603
RESISTOR_R0603_4.7K_0603
RESISTOR_R0603_4.7K_0603
RESISTOR_R0603_10K_0603
RESISTOR_R0805_22E_0805
RESISTOR_R0603_470E_0603
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0603_1K_0603
RESISTOR_R0603_10K_0603
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0603_10K_0603
RESISTOR_R0805_22E_0805
RESISTOR_R0402_0_0402
RESISTOR_R0805_22E_0805
RESISTOR_R0603_10K_0603
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0603_10K_0603
RESISTOR_R0603_470E_0603
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0805_22E_0805
RESISTOR_R0805_22E_0805
RESISTOR_R0402_0_0402
RESISTOR_R0603_10K_0603
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R0603_470E_0603
RESISTOR_R0805_22E_0805
RESISTOR_R0805_22E_0805
RESISTOR_R0805_100_0805
RESISTOR_R0805_1K_0805
RESISTOR_R1206_275K_1206
RESISTOR_R1206_275K_1206
RESISTOR_R0805_275K
www.excelpoint.com
BEED_1000_Ohms
BEED_1000_Ohms
BEED_1000_Ohms
BEED_1000_Ohms
IC
IC
IC
IC
FB20
FB21
FB22
FB23
OPTO ISOLATOR
CON2
CON2
CON2
CON2
RJ11
ICD CONNECTOR
PIC Kit Connector
CON4
CON2
CON3
BC557 /BC857
BC557 /BC857
BC557 /BC857
BC857
BC547
BC557 /BC857
BC547
BC547
BC847
100_0805
1K_0805
22E_0805
4.7K_0603
4.7K_0603
4.7K_0603
4.7K_0603
10K_0603
22E_0805
470E_0603
100_0805
1K_0805
1K_0603
10K_0603
100_0805
1K_0805
10K_0603
22E_0805
0_0402
22E_0805
10K_0603
100_0805
1K_0805
10K_0603
470E_0603
100_0805
1K_0805
22E_0805
22E_0805
0_0402
10K_0603
100_0805
1K_0805
100_0805
1K_0805
470E_0603
22E_0805
22E_0805
100_0805
1K_0805
275K_1206
275K_1206
275K
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
ISO1
J1
J2
J3
J4
J5
J6
J7
J8
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Q1
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R0603
R0402
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R0603
R0402
R0603
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R0402
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R0402
R0402
R0402
R0402
R0603
R0603
R0603
R0603
R0603
R0603
R0603
3 Ph Energy Meter Reference Design
RESISTOR_R0805_275K
RESISTOR_R0805_1K
RESISTOR_R0805_470E_0603
RESISTOR_R0805_1K_0805
RESISTOR_R1206_275K_1206
RESISTOR_R1206_275K_1206
RESISTOR_R0805_275K
RESISTOR_R0805_275K
RESISTOR_R0805_1K
RESISTOR_R0805_1K_0805
RESISTOR_R0805_0_0402
RESISTOR_R1206_275K_1206
RESISTOR_R1206_275K_1206
RESISTOR_R0805_275K
RESISTOR_R0805_275K
RESISTOR_R0805_1K
RESISTOR_R0805_1K_0805
R_R0402_0_0402
R_R0402_0_0402
R_R0603_120E_0603
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0603_4.7K_0603
R_R0603_4.7K_0603
R_R0402_0_0402
R_R0603_4.7K_0603
R_R0603_10K_0603
R_R0603_2.2K_0603
R_R0603_2.2K_0603
R_R0603_1K_0603
R_R0603_10K_0603
R_R0402_0_0402
R_R0603_33K_0603
R_R0603_56E_0603
R_R0603_33K_0603
R_R0603_33K_0603
R_R0603_100E_0603
R_R0603_10K_0603
R_R0603_1K_0603
R_R0603_100E_0603
R_R0603_4.7K_0603
R_R0603_10K_0603
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0603_10K_0603
R_R0603_10K_0603
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0402_0_0402
R_R0603_10K_0603
R_R0603_10K_0603
R_R0603_4.7K_0603
R_R0603_10K_0603
R_R0603_20K_0603
R_R0603_1K_0603
R_R0603_10K_0603
www.excelpoint.com
275K
1K
470E_0603
1K_0805
275K_1206
275K_1206
275K
275K
1K
1K_0805
0_0402
275K_1206
275K_1206
275K
275K
1K
1K_0805
0_0402
0_0402
120E_0603
0_0402
0_0402
0_0402
0_0402
0_0402
0_0402
0_0402
4.7K_0603
4.7K_0603
0_0402
4.7K_0603
10K_0603
2.2K_0603
2.2K_0603
1K_0603
10K_0603
0_0402
33K_0603
56E_0603
33K_0603
33K_0603
100E_0603
10K_0603
1K_0603
100E_0603
4.7K_0603
10K_0603
0_0402
0_0402
0_0402
0_0402
0_0402
0_0402
0_0402
0_0402
10K_0603
10K_0603
0_0402
0_0402
0_0402
0_0402
10K_0603
10K_0603
4.7K_0603
10K_0603
20K_0603
1K_0603
10K_0603
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
R44
R45
R46
R47
R48
R49
R50
R51
R52
R53
R54
R55
R56
R57
R58
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R96
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R103
R104
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R107
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R109
R110
R111
R112
Page 14
239
240
241
R0603
R0603
R0805
242
TH_4_SW_B3F1022_360H
243
244
245
246
247
248
249
250
251
252
253
254
255
TH_4_SW_B3F1022_360H
TP2P5MM
TP2P5MM
TP2P5MM
TP2P5MM
SM_40_QFN_19P68_40H
SO16_50_300X413W
QSOP16_25_19_208X244
SO16_50_300X413W
SM_8_SOIJ_50P_80H
SO8_50_157X197
TQFP64_19_69_393SQ
SOT23_118X063X050
R_R0603_100K_0603
R_R0603_100K_0603
RESISTOR_R0805_0_0402
SW PUSHBUTTON-SPST2_TH_4_SW_B3
SW PUSHBUTTON-SPST2_TH_4_SW__1
TEST POINT_TP2P5MM_TEST POINT
TEST POINT_TP2P5MM_TEST POINT
TEST POINT_TP2P5MM_TEST POINT
TEST POINT_TP2P5MM_TEST POINT
ICL232/SO_4_SM_40_QFN_19P68_40H
ICL232/SO_1_SO16_50_300X413W_AD
ICL232/SO_2_QSOP16_25_19_208X24
ICL232/SO_5_SO16_50_300X413W_AD
CON8A_2_SM_8_SOIJ_50P_80H_24AA1
CON8A_3_SO8_50_157X197_MCP79400
ICL232/SO_3_TQFP64_19_69_393SQ_
AF150_0_SOT23_118X063X050_AH180
256
257
SM_5_TSOT_50H
SM_2_XTAL_170H
ADP120ACBZ12R7_1_SM_5_TSOT_50H_
CRYSTAL_5_SM_2_XTAL_170H_16.384
258
259
TH_3_CRYT_340H
SM_2_XTAL_170H
CRYSTAL_4_TH_3_CRYT_340H_CM7V-T
CRYSTAL_6_SM_2_XTAL_170H_8MHZ
100K_0603
100K_0603
0_0402
IC
IC
IC
R113
R114
R115
KEY2
IC
SW1
KEY1
TEST POINT
TEST POINT
TEST POINT
TEST POINT
ADE7878
ADM2484E
ADM3101E
ADuM2281
24AA1026
MCP79400
PIC24FJ128GA306
AH180
ADP150AUJZ_3.3_
RZ
16.384MHz
CM7V-T1A_32.768
kHz
8MHz
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
IC
SW2
TP1
TP2
TP3
TP4
U1
U2
U3
U4
U5
U6
U7
U8
IC
IC
U9
Y1
IC
IC
Y2
Y3
Gerber Files
PCB View
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 15
Top Side PCB View
Bottom Side PCB View
f. PCB Layouts Guidelines
Below Figure presents a basic schematic of the ADE7878 together with its surrounding circuitry: decoupling capacitors
at pins VDD, AVDD, DVDD and REFIN/OUT, the 16.384 MHz crystal and its load capacitors. The rest of the pins are
dependent on the particular application and are not shown here. The ADE7854, ADE7858 and ADE7868 have an
identical approach to the decoupling capacitors, the crystal and its load capacitors.
3 Ph Energy Meter Reference Design
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Page 16
Figure 91 and Figure 92 present a proposed layout of a printed circuit board (PCB) with two layers that have the
components placed only on the top of the board. Following these layout guidelines will help in creating a low noise
design with higher immunity to EMC influences.
The exposed pad of the ADE7878 is soldered to an equivalent pad on the PCB. The AGND and DGND traces of the
ADE7878 are then routed directly into the PCB pad.
The bottom layer is composed mainly of a ground plane surrounding as much as possible the crystal traces.
3 Ph Energy Meter Reference Design
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Page 17
3 S/W implementation
a. Microcontroller Flow Chart
Start 3Phase Energy Meter
Initialize the MCU peripherals & I/O’s
B
Initialize ADE7878 interface
Display the parameters in LCD
NO
Check the receive
packet flag is set?YES
YES
Receive char function will check the
command which received in the packet.
NO
Check the Flag
energy A for
calibration is set?
YES
Transmit channel A Calibration energy
value in line accumulation mode.
A
interfacwe
3 Ph Energy Meter Reference Design
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Page 18
A
NO
YES
Check the Flag
energy B for
calibration is set?
NO
YES
Transmit channel B Calibration energy
value in line accumulation mode.
NO
Check the Flag
energy C for
calibration is set?
YES
Transmit channel C Calibration energy
value in line accumulation mode.
B
3 Ph Energy Meter Reference Design
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Page 19
i. Peripheral usage
Peripheral Pin Usage
MCU PINs Connections
MCU PINs Connections
MCU PINs Connections
MCU PINs Connections
1 LCDBIAS2/RESET for ADE7878
17 RS4845 DE/RE enable
33 SEG12
49 KEY1
2 LCDBIAS1/PM1 for ADE7878
18 IRQ1 for ADE7878
34 TXD
50 SEG21
3 LCDBIAS0/PM0 for ADE7878
19 AVDD
35 POWER FAIL INT
51 SEG22
4 SEG0
20 AVSS
36 SDA1
52 SEG23
5 VLCAP
21 IRQ0 for ADE7878
37 SCL1
53 SEG8
6 VLCAP
22 KEY2
38 VDD
54 SEG9
7 MCLR-RESET
23 CF1 / Pwr Cntrl
39 XC
55 SEG10
8 SEG1
24 SS for ADE7878
40 XC
56 VDD CORE
9 VSS1
25 VSS
41 VSS
57 VBAT
10 VDD1
26 VDD
42 SEG13
58 SEG11
11 SEG2
27 SEG18
43 SEG14
59 SEG20
12 SEG3
28 SEG19
44 SEG15
60 COM3
13 SEG4
29 CF3/HSCLK for ADE787
45 SEG16
61 COM2
14 SEG5
30 MISO for ADE7878
46 SEG17
62 COM1
15 SEG6/PGC
31 MOSI for ADE7878
47 nc
63 COM0
16 SEG7/PGD
32 SCK FOR ADE7878
48 RXD
64 Magnetic sense/CF2
ii. Display Parameters explanations
Display Sequence
3 Ph Energy Meter Reference Design
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Page 20
b. Functions used with explanation
c. Calibration process
The calibration for the 3 phase energy meter can be done with two methods, one using a reference meter and one
using an accurate source method. In this meter, we are used as reference method. Single point calibration is required
for this meter. The following parameters we need to calibrate.
1.
Voltage Calibration for three channels
2.
Current calibration for three channels
3.
Apparent Power Calibration for three channels
4.
Active Power Calibration for three channels
5.
Reactive Power Calibration for three channels
6.
Active Energy Calibration for three channels
7.
Phase Calibration for three channels
8.
Voltage Calibration for three channels
The each phase voltage registers are AVRMS, BVRMS and CVRMS. For example, if the input of the supply is
240V, and you are getting a hex value 0x2D3AA0 in the AVRMS register and our firmware variable using a
multiplier AVrms_Multiplier.
Factor= AVRMS register/240V
AVrms_Multiplier=1/ Factor
Display the exact Voltage Value in channel A= AVRMS register X AVrms_Multiplier
Eg: -
Factor= 0x2D3AA0/240V =2964128/240
Factor=12350.53
AVrms_Multiplier= 0.0000809 (This multiplier value stored in external eeprom)
Display the exact Voltage Value in channel A=2964128 x 0.0000809 =239.9
Similary we can find the BVrms_Multiplier and CVrms_Multiplier.
3 Ph Energy Meter Reference Design
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Page 21
9.
Current Calibration for three channels
The each phase voltage registers are AIRMS, BIRMS and CIRMS. For example, if the input of the supply is
240V, and you are getting a hex value 0x2D3AA0 in the AVRMS register and our firmware variable using a
multiplier AVrms_Multiplier.
Factor= AIRMS register/240V
AIrms_Multiplier=1/ Factor
Display the exact Voltage Value in channel A= AVIMS register X AIrms_Multiplier
Eg: -
Factor= 0x2D3AA0/240V =2964128/240
Factor=12350.53
AIrms_Multiplier= 0.0000809 (This multiplier value stored in external eeprom)
Display the exact current Value in channel A=2964128 x 0.0000809 =239.9
Similary we can find the BIrms_Multiplier and CIrms_Multiplier.
10.
Apparent Power Calibration for three channels
Apparent power is calibrated as same as above mentioned. Read the apparent power register and find out the
apparent power multiplier (AVA_Multiplier) and store the value in eeprom location.
11.
Active Power Calibration for three channels
Active power is calibrated as same as above mentioned. Read the active power register and find out the active
power multiplier (AWATT_Multiplier) and store the value in eeprom location.
12.
Active Energy Calibration
Step 1: input R3 and R4, display VFs
Step 2: input R1 and R2, display Ifs
Step 3: input Vn and In, display Vrmsref and Irmsref
Step 4: input meter constant, display CFDEN
Step 5: input VRMSref, IRMSref, Vn, In, CFDEN, MC, display THR (threshold)
The below equations to find out above parameters
Input parameters R3 & R4 and find out Vfs
Vfs->Full scale voltage
3 Ph Energy Meter Reference Design
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Page 22
To find out Vfs,
Example R3=1000 ohm & R4=1.07Mohm
VFS=387.7V
Input parameters R1, R2 & CT ratio and find out Ifs
Ifs->Full scale current
Example R1=5.1ohm, R2=5.1ohm & CT RATIO =2500
Ifs=0.5 x 2500/ ((5.1+5.1) X 1.414)
Ifs=86.65 Amps
Input parameter Vn (normal voltage) & In (normal current)
To find out Vrms ref and Irms ref
3 Ph Energy Meter Reference Design
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Page 23
Example
Vrms ref =240/388 X 4191910= 2592934
Irmsref= 10/86.65 x 4191910=483774
Input the meter constant and find out CFxDEN
If meter constant is 6400
Example Meter constant for our meter is 416
CFxDEN=2403.8
To find out threshold
VRMSref, IRMSref, fs, Vn, In, CFDEN, MC are calculated by above formula
Example
VRMSref =2592934, IRMSref=483774, fs=8000, Vn=240V, In=10amp, CFDEN=2404, MC=416
THR= (2592934.02 x 483774.95 x 8000 x3.6 x1000000) / (524288 x 240 x 10 x416 x2404)
THR=28709020 in decimal
To calibrate the active energy, to find out the Active gain of each channels of the ADE7878
Apply 240V and 10 Amp, PF=1 and CF =30 pulses on Channel A and read the pulse and find the error.
Find out the error of reference meter and take five readings and average it.
AWGAIN= -Error/ (Error+100)
For example if Error value is from reference meter
Readings -3.54, -3.55, - 3.70,-3.67,-3.82 and Average is- 3.65
AWGAIN=3.65/100-3.65
AWGAIN=0.037882
Convert the value in to HEX =223 x 0.037882=0x4D957
AWGAIN=0x04D957 load the value in the AWAGIN register then the meter is calibrated for PF=1.
Similarly B and C channel can be calibrated and load the gain value in the BWGAIN and CWGAIN registers.
These gain value is saved in the eeprom locations once the meter is calibrated after the power on reset it will load
the values from the eeprom to the ADE7878 registers.
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 24
d. GUI Software explanation
1. In the communication setup window, the meter can be selected either RS232 or WiFi.
2. The baud rate for serial communication is 9600b/s.
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 25
In the above figure is the our calibration GUI
1. The top left side of the window Meter_Time shows the Meter current time.
2. The top left side of the window Meter ID shows the Meter ID for eg: (ES0002).
3. In the R Phase window in ping colour shows the meter current status parameters.
4. RV  R Phase voltage
5. RFR R Phase Frequency
6. RI
R Phase Current
7. RPF R Phase Power Factor
8. RAP R Phase Apparent Power
9. RAC R Phase Active Power
10.
RACE
R Phase Active Energy
11.
To calibrated the R phase voltage, enter the source exact voltage in the source volt window box and press
the calibrate button after 5 second the meter R Phase volte is calibrated.
12.
To calibrated the R phase current , enter the source exact current in the source current window box and
press the calibrate button after 5 second the meter R Phase current is calibrated.
13.
To calibrated the R phase apparent power, enter the source exact RAP in the source RAP window box and
press the calibrate button after 5 second the meter R phase apparent power is calibrated.
14.
To calibrated the R phase active power, enter the source exact RAC in the source RAC window box and
press the calibrate button after 5 second the meter R phase active power is calibrated.
15.
To press the button on R Phase active energy, popup window will ask to input the error of active energy
from the reference meter, if you enter the error it will automatically calibrate the active energy of the meter.
16.
Similar Y Phase and B Phase can be calibrated.
17.
If you press the auto calibration button it will calibrate the all the phase automatically.
3 Ph Energy Meter Reference Design
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Page 26
18.
Phase Calibration ,if you press that button, it will ask the R,Y,B phase calibration registers value , we need
to enter the phase calibration calculated register value using the slider key, which is show in the below
image for all the three channels. When you press R Phase Cal button it will store the phase calibrate value
in the APCAL register. Similarly the other two channels.
e. PF calibration
Power Factor can be calibrate by the equation PF=active power register value /apparent power register value of each
channels.
f. Energy, Phase Error calibration for R, Y & B phases
Phase error can be calibrate by lead and lag.
PF=-0.5 is lag and PF=+0.5 is the lead.
-1
x=sin (-error/√3 x 100)
3 Ph Energy Meter Reference Design
www.excelpoint.com
Page 27
g. Tamper Flow Chart
The magnetic tamper detection done using AH180 sensor. If the magnetic field is near to the CT the O/P of the AH180
sensor logic level will be high.
Start
No
AH180 O/P
is high
Tamper Detected
Tamper Flag is set
Tamper Detected
Tamper Flag is not
set
3 Ph Energy Meter Reference Design
Yes
www.excelpoint.com
Page 28
h.
Test Report Summary
Meter SL 197419
Meter Constant is 416
Reference Meter Make Accucek - LT+, 5 Amp to 10Amps Class 0.2, Clamp CT 100 Amps Class 0.5
PF= 1, 10 Amp,
240V
30 Pulse Reading
-0.2
-0.19
-0.19
-0.19
-0.23
-0.21
-0.23
-0.22
-0.21
-0.21
-0.20
3 Ph Energy Meter Reference Design
PF= 1, 5 Amp,
240V
30 Pulse
Reading
-0.18
-0.16
-0.14
-0.14
-0.16
-0.15
-0.14
-0.15
-0.13
-0.13
-0.14
PF= 1, 2.5 Amp,
240V
15 Pulse
Reading
-0.04
-0.08
-0.03
-0.03
-0.01
-0.01
-0.04
-0.02
-0.03
0
-0.29
www.excelpoint.com
PF= 1, 1A,
240V
10 Pulse
Reading
0.06
0.08
0.09
0.04
0.04
0.062
PF= 1, 500mA,
240V
5 Pulse Reading
-0.14
-0.18
-0.15
-0.1
-0.14
-0.14
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4 Reference
Calibrating an ADE7878-Based, 3-Phase Energy Meter
http://www.analog.com/static/imported-files/application_notes/AN-1076.pdf
Frequently Asked Questions (FAQs) Analog Devices Energy (ADE) Products
http://www.analog.com/static/imported-files/application_notes/AN-639.pdf
Key Features of ADE7878 Poly Phase Energy Metering IC
http://www.analog.com/static/imported-files/tech_articles/Met_Intl_Mar_09_60_Analog_new.pdf
Evaluating the ADE7878 Energy Metering IC
http://www.analog.com/static/imported-files/user_guides/UG-146.pdf
3 Ph Energy Meter Reference Design
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Contact
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