71M6533 Datasheet, PDF (101/132 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS_6533_6534_004
71M6533/G/H and 71M6534/H Data Sheet
WSUM_X and VARSUM_X are the signed sum of Phase-A, Phase-B and Phase-C Wh or VARh values
according to the metering equation specified in the I/O RAM register EQU[2:0]. WxSUM_X is the Wh value
accumulated for phase x in the last accumulation interval and can be computed based on the specified
LSB value.
For example, with VMAX = 600 V and IMAX = 208 A, the LSB for WxSUM_X is 0.1173 µWh.
Instantaneous Energy Measurement Variables
Table 61 contains various measurement variables. IxSQSUM_X and VxSQSUM are the squared current and
voltage samples acquired during the last accumulation interval. They can be used to calculate RMS voltages
and currents. INSQSUM_X can be used for computing the neutral current.
CE
Address
0x8F
0x90
0x91
0x92
0x99
0x9A
0x9B
0x9C
0x93
0x94
0x95
Table 61: CE Energy Measurement Variables
Name
I0SQSUM_X
I1SQSUM_X
I2SQSUM_X
INSQSUM_X
I0SQRES_X
I1SQRES_X
I2SQRES_X
INSQRES_X
V0SQSUM_X
V1SQSUM_X
V2SQSUM_X
Description
The sum of squared current samples from each element.
LSB_I = 9.4045*10^-13 IMAX² / In_8² A²h
The sum of squared current samples from the calculated neutral:
∑^(I0 ^{+ I}1 ^{+ I}2 ⁾²
LSB=9.4045*10^-13 IMAX² / In_8² A²h
Residual current measurements with double-precision accuracy. The
exact current is:
ISQn = InSQSUM_X + InSQRES_X
The sum of squared voltage samples from each element.
LSB_V= 9.4045*10^-13 VMAX² V²h
The RMS values can be computed by the MPU from the squared current and voltage samples as follows:
Ix_RMS =
IxSQSUM ⋅ LSB_I ⋅3600 ⋅ F_S
N _ACC
Vx_RMS =
VxSQSUM ⋅ LSB_V ⋅ 3600 ⋅ F_S
N _ACC
Other Transfer variables include those available for frequency and phase measurement, and those reflecting
the count of the zero-crossings of the mains voltage and the battery voltage. These transfer variables are
listed in Table 62.
MAINEDGE_X reflects the number of half-cycles accounted for in the last accumulated interval for the AC
signal of the phase specified in the FREQSEL1 and FREQSEL0 registers. MAINEDGE_X is useful for
implementing a real-time clock based on the input AC signal.
Rev 2
101