78M6612 Data Sheet
DS_6612_001
4.4.7.1 Fundamental Energy Measurement Variables
The table below describes each transfer variable for fundamental energy measurement. All variables are
signed 32 bit integers. Accumulated variables such as WSUM are internally scaled so they have at least
2x margin before overflow when the integration time is 1 second. Additionally, the hardware will not
permit output values to ‘fold back’ upon overflow.
CE
Address
Name
Description
0x74
W1SUM_X
W2SUM_X
VAR1SUM_X
The sum of Watt samples from each measurement element (In_8 is the
gain configured by IA_SHUNT or IB_SHUNT).
LSB = 1.67380 *10-13 VMAX * IMAX / In_8 Wh.
0x75
0x76
The sum of VAR samples from each measurement element (In_8 is the
gain configured by IA_SHUNT or IB_SHUNT).
0x77
VAR2SUM_X
LSB = 1.67380 *10-13 VMAX * IMAX / In_8 Wh.
WxSUM_X is the Wh value accumulated for element ‘X’ in the last accumulation interval and can be
computed based on the specified LSB value.
For example with VMAX = 600V and IMAX = 52A, LSB (for WxSUM_X) is 0.005222 µWh.
4.4.7.2 Instantaneous Energy Measurement Variables
The Frequency measurement is computed using the Frequency locked loop for the selected phase.
IxSQSUM_X and VxSQSUM are the squared current and voltage samples acquired during the last
accumulation interval. INSQSUM_X can be used for computing the neutral current.
CE
Address
Description
Name
FS
232
≈ 0.587 ⋅10−6 Hz
FREQ_X
0x72
Fundamental frequency. LSB ≡
I1SQSUM_X
I2SQSUM_X
V1SQSUM_X
V2SQSUM_X
0x78
The sum of squared current samples from each element.
LSB = 4.1845*10-14 IMAX2 A2h
0x79
0x7A
0x7B
The sum of squared voltage samples from each element.
LSB= 6.6952 * 10-13 VMAX2 V2h
The sum of squared voltage difference samples (V1-V2) between the
elements.
LSB= 6.6952 * 10-13 VMAX2 V2h
0x7C
0x18
V3SQSUM_X
WSUM_ACCUM
This is the roll-over accumulator for WPULSE.
The RMS values can be computed by the MPU from the squared current and voltage samples as follows:
IxSQSUM ⋅ LSB ⋅3600⋅ FS
VxSQSUM ⋅ LSB⋅3600⋅ FS
IxRMS
=
VxRMS
=
NACC
NACC
86
Rev. 1.2
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
