90E32 Datasheet, PDF (18/71 Pages) Integrated Device Technology – Poly-Phase High-Performance Wide-Span Energy Metering IC

90E32
POLY-PHASE HIGH-PERFORMANCE WIDE-SPAN ENERGY METERING IC
3.5.5 PHASE ANGLE
Phase Angle measurement registers can be divided as below:
- phase A / phase B / phase C
- voltage / current
Altogether there are 6 phase angle registers. Refer to 6.6.3 THD+N,
Frequency, Angle and Temperature Registers.
Note: Calculation of phase angle is based on zero-crossing interval
and frequency. There might be big error when voltage/current at low
value.
3.5.6 FREQUENCY
Frequency is measured using phase A voltage by default. When
phase A has voltage sag, phase C is used, and phase B is used when
both phase A and C have voltage sag.
Refer to 6.6.3 THD+N, Frequency, Angle and Temperature Regis-
ters.
3.5.7 TEMPERATURE
Chip Junction-Temperature is measured roughly every 100 ms by on-
chip temperature sensor.
Refer to 6.6.3 THD+N, Frequency, Angle and Temperature Regis-
ters.
3.5.8 THD+N FOR VOLTAGE AND CURRENT
Voltage THD+N is defined as:
(V - V ) 2
rms_total
2
rms_fundam ental
Vrms_fundam ental
Current THD+N's definition is similar to that of voltage.
Registers:
- voltage and current
- phase A / phase B / phase C
Altogether there are 6 THD+N registers. Refer to 6.6.3 THD+N, Fre-
quency, Angle and Temperature Registers.
The THD+N measurement is mainly used to monitor the percentage
of harmonics in the system. Accuracy is not guaranteed when THD+N is
lower than 10%.
Function Description
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December 9, 2011