Rainbow Electronics 71M6542G - Manual (Page 131)

v1.1 © 2008–2011 Teridian Semiconductor Corporation 131
5.3.8.2 Instantaneous Energy Measurement Variables
IxSQSUM_X and VxSQSUM (see Table 87 ) are the sum of the squared current and voltage samples
acquired during the last accumulation interval.
Table 87: CE Energy Measurement Variables (with Local Sensors)
CE
Address
Name Description
Configuration
0x8C I0SQSUM_X The sum of squared current samples from each
element.
LSB
I
= 9.4045*10
-13
IMAX
2
A
2
h
When EQU = 1, I0SQSUM_X is based on IA and
IB.
Figure 35 (page 93 )
Figure 37 (page 95 )
0x8D I1SQSUM_X
0x90 V0SQSUM_X
The sum of squared voltage samples from each
element.
LSB
V
= 9.4045*10 -13 VMAX 2 V 2 h
0x91
†
V1SQSUM_X
†
71M6542 only.
Table 88: CE Energy Measurement Variables (with Remote Sensor)
CE
Address
Name Description Configuration
0x8C I0SQSUM_X The sum of squared current samples from each
element.
LSB
I
= 2.55872*10 -12 * IMAX 2 A 2 h
When EQU = 1, I0SQSUM_X is based on IA and
IB.
Figure 36 (page 94 )
Figure 38 (page 96 )
0x8D I1SQSUM_X
0x90 V0SQSUM_X The sum of squared voltage samples from each
element.
LSB
V
= 9.40448*10
-13
* VMAX
2
V
2
h
0x91
†
V1SQSUM_X
†
71M6542 only.
The RMS values can be computed by the MPU from the squared current and voltage samples as follows:
Note: N
ACC
= SUM_SAMPS[12:0] (CE RAM 0x23).
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 89.
MAINEDGE_X (CE RAM 0x83) reflects the number of half-cycles accounted for in the last accumulated
interval for the AC signal of the phase specified in the FREQSEL[1:0] field in CECONFIG (CE RAM 0x20[7:6]).
MAINEDGE_X is useful for implementing a real-time clock based on the input AC signal.
ACC
S I
RMS
N
F LSB IxSQSUM
Ix
⋅ ⋅ ⋅
=
3600
ACC
S V
RMS
N
F LSB VxSQSUM
Vx
⋅ ⋅ ⋅
=
3600