Cirrus Logic AN362 User Manual
Power Source
U
n
I
b
CS5480
VIN 1+
VIN1-
N3
U3
CDB5480U
I3
PPS400.3
Power R eferen ce
U3
N3
I3
PRS400.3
Energy P ulses
+3.3V DC Power Supply
+3.3V GND
USB
M
C
U
DO1
TX
RX
PC
CDB5480U GUI
CAMCAL
®
for
WINDOWS
RS232
RS232
Current
Sensor
METE R
SH2003
IIN1-
IIN1+
27n
27n
1K100
1K100
27n
27n
GND
IIN1-
IIN1+
J1
V+
V-
GND
27n
27n
LINE 1
GND
J4
422K 422K 422K422K
1K
Figure 1. Test Setup Connection Diagram
AN362
Application Note
CS5480/84/90 Measurement Accuracy
vs. IEC Standards
1. Introduction
Cirrus Logic’s CS5480, CS5484, and CS5490 energy measurement ICs benefit from on-chip, high-performance, 24bit ADC converters in conjunction with its digital calibration and compensation algorithms. This application note presents accuracy results from testing the CS5480. The CS5484 and CS5490 uses the same core technology as the
CS5480. Testing results of the CS5484 and CS5490 show nearly identical results.
The CS5480 has world-leading accuracy over an extensive, dynamic range. This application note cites measurements of active energy, reactive energy, and I
types of current sensor: Rogowski coil, current transformer (CT), and shunt. A comparison between the CS5480
measurements and the IEC 62053 standards is presented. This comparison shows that the CS5480 meets IEC
62053-22 class 0,2S standards for active energy and IEC 62053-23 class 2 standards for reactive energy. Comparison with the ANSI C12.20 standard is not included in this application note because the ANSI standard is less stringent than the IEC 62053 standard, so it is implied that the CS5480 meets it.
load performance acquired from the CS5480 using three different
RMS
2. Test Setup
The following diagram illustrates the connections between the PPS400.3 power source, PRS400.3 power reference,
current sensor, CDB5480U board (+3.3V DC power supply), and a host PC.
Cirrus Logic, Inc.
http://www.cirrus.com
Copyright Cirrus Logic, Inc. 2012
(All Rights Reserved)
MAR’12
AN362REV1
AN362
The Cirrus Logic CDB5480U demonstration board and current sensor form a single-phase, two-wire energy meter.
The CDB5480U software is installed on a host PC and used to configure, calibrate, and control the meter using the
USB port. The software collects the measurement results from the CS5480 registers once per second. CAMCAL
for WINDOWS software controls the MTE Meter Test Equipment AG PPS400.3 power source and PRS400.3 power
reference using two COM ports. CAMCAL performs the active and reactive accuracy test procedure automatically.
The active or reactive energy pulses provided by the CS5480 drive the on-board LED using energy pulse output
DO1. The energy pulses are sensed by photoelectric scanning head SH2003 and directed back into PRS400.3. The
accuracy of the active and reactive energy is then measured by PRS400.3 and sent to the CAMCAL software. The
meter constant is 2000 impulses/ kWh, or 2000 impulses/ kVarh.
I
accuracy is manually calculated and based on a 10-second average using the I
RMS
register is read once per second using the CDB5480U software.
2.1Calibrations and Meter Types
Prior to the accuracy test, the following calibrations and compensations were performed:
• Gain calibration
• AC offset calibration
• Phase compensation
• Active and reactive power offset correction
Using the CDB5480U board with different current sensors forms different types of meters. To test the accuracy of
the CS5480, the following meters were formed:
register values. The I
RMS
RMS
®
• Rogowski coil meter, where U
• Current transformer (CT) meter, where U
• Shunt meter, where U
= 240V and I
n
= 240V and I
n
b(max)
= 2 (80A) at 50Hz
b(max)
= 240V and I
n
b(max)
= 2.5 (100A) at 50Hz
= 2.5 (100A) at 50Hz
All accuracy tests were conducted at room temperature. Influences from ambient temperature and self-heating are
not included.
Refer to Application Note 366, entitled CS5480/ 84 / 90 Power Meter Calibration, for more information about calibra-
tions and compensations.
Refer to the CDB5480U data sheet, entitled CDB5480U Engineering Board and GUI Software, for more information
about the CDB5480U board.
Refer to the CS5480 data sheet, entitled Three Channel Energy Measurement IC, for more information about the
CS5480.
2 AN362REV1
AN362
CS5480
IIN 1-
IIN 1+
27nF
27nF
1K Ω100Ω
1KΩ100Ω
27nF
27nF
V+
V-
GND
GND
IIN1-
IIN1+
J1
Rogow s ki Coi l
PA 3202 NL
Current
3. Accuracy Test with Rogowski Coil, Un = 240V and I
b(max)
= 2(80A) at 50Hz
Pulse PA3202NL is used as the current sensor. The secondary output voltage of PA3203NL is 416μV/A at
50Hz. When the meter is applied with the maximum load current, I
put is approximately 33 mV
, which is below the CS5480 maximum I-channel input range when setting the
RMS
= 80A, the Rogowski coil secondary out-
max
PGA for current channel 1 (I1) to 50x.
High-pass filter (HPF) is enabled on the voltage channel: V1FLT[1:0] = ‘01’
Integrator is enabled on the current channel: I1FLT[1:0] = ‘11’
Figure 2. Connection between Rogowski Coil and CS5480
AN362REV1 3
3.1Accuracy Results for Active Energy Load Performance
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.01 0.1 1 10 100
Percent Error (%)
Load Current (A)
PF = 1 Lagging PF = 0.5 Leading PF = 0.5
Note: CS5480, where Un = 240 V, I
b(max)
= 2 (80 A) at 50 Hz
IEC 62053-22 Class 0,2S Spec, Lagging PF = 0.5 or Leading PF = 0.8
IEC 62053-22 Class 0,2S Spec, PF = 1
AN362
Figure 3. Active Energy Load Performance vs. IEC 62053-22 Class 0,2S Standard
Power Factor Load Current (A) Current Dynamic Range (x:1) Error
80 1 0.04%
8 10 0.04%
0.8 100 0.04%
PF = 1
0.16 500 0.04%
0.08 1000 0.07%
0.04 2000 0.05%
0.03 3333 0.06%
0.02 4000 0.02%
80 1 0.05%
8 10 0.05%
Lagging PF = 0.5
0.8 100 0.04%
0.16 500 0.06%
0.08 1000 0.05%
0.04 2000 0.06%
80 1 0.04%
Leading PF = 0.5
8 10 0.04%
0.8 100 0.05%
0.16 500 0.04%
0.08 1000 0.05%
0.04 2000 0.07%
Table 1. Active Energy Load Performance
4 AN362REV1
3.2Accuracy Results for Reactive Energy Load Performance
-3
-2
-1
0
1
2
3
0.01 0.1 1 10 100
Percent Error (%)
Load Current (A)
sin ࢥ = 1 Lagging sin ࢥ = 0.5 Leading sin ࢥ = 0.5
Note: CS5480, where Un = 240 V, I
b(max)
= 2 (80 A) at 50 Hz
IEC 62053-23 Class 2 Spec, sinࢥ = 0.5
IEC 62053-23 Class 2 Spec, sinࢥ = 1
AN362
Figure 4. Reactive Energy Load Performance vs IEC 62053-23 Class 2 Standard
Power Factor Load Current (A) Current Dynamic Range (x:1) Error
80 1 0.00%
8 10 0.01%
0.8 100 0.01%
sin = 1
0.16 500 -0.02%
0.08 1000 -0.02%
0.04 2000 -0.01%
0.03 3333 0.00%
Lagging sin = 0.5
0.02 4000 -0.03%
80 1 0.23%
8 10 0.24%
0.8 100 0.17%
0.16 500 0.21%
0.08 1000 0.16%
0.04 2000 0.22%
80 1 -0.20%
Leading sin = 0.5
8 10 -0.20%
0.8 100 -0.26%
0.16 500 -0.23%
0.08 1000 -0.25%
0.04 2000 -0.24%
Table 2. Reactive Energy Load Performance
AN362REV1 5
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