Cirrus Logic AN362 - Manual (Page 2)

AN362
2 AN362REV1
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
RMS
accuracy is manually calculated and based on a 10-second average using the I
RMS
register values. 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:
• Rogowski coil meter, where U
n
= 240V and I
b(max)
= 2 (80A) at 50Hz
• Current transformer (CT) meter, where U
n
= 240V and I
b(max)
= 2.5 (100A) at 50Hz
• Shunt meter, where U
n
= 240V and I
b(max)
= 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.