71M6521DE/71M6521FE
Energy Meter IC
DATASHEET
JANUARY 2008
CECONFIG
Name
Default
Description
[bit]
Number of consecutive voltage samples below SAG_THR before a sag
alarm is declared. The maximum value is 255. SAG_THR is at address
0x14.
80
(0x50)
[15:8]
SAG_CNT
[7]
[6]
--
0
0
Unused
FREQSEL
Selected phase for frequency monitor (0 = A, 1 = B).
When zero, causes the pulse generators to respond to WSUM_X and
VARSUM_X. Otherwise, the generators respond to values the MPU places
in APULSEW and APULSER.
[5]
EXT_PULSE
1
[4]
[3]
[2]
--
0
0
0
Unused
When 1, the current gain of channel B is increased by 8. The gain factor
controlled by In_SHUNT is referred to as In_8 throughout this document.
IB_SHUNT
IA_SHUNT
When 1, the current gain of channel A is increased by 8.
When PULSE_SLOW = 1, the pulse generator input is reduced by a factor of
64. When PULSE_FAST = 1, the pulse generator input is increased 16x.
These two parameters control the pulse gain factor X (see table below).
Allowed values are either 1 or 0. Default is 0 (X = 6).
[1]
[0]
PULSE_FAST
PULSE_SLOW
0
0
X
PULSE_SLOW
PULSE_FAST
1.5 * 22 = 6
1.5 * 26 = 96
1.5 * 2-4 = 0.09375
1.5
0
0
1
1
0
1
0
1
CE TRANSFER VARIABLES
When the MPU receives the XFER_BUSY interrupt, it knows that fresh data is available in the transfer variables. The transfer
variables can be categorized as:
1.
2.
3.
4.
5.
6.
Fundamental energy measurement variables
Instantaneous (RMS) values
Other measurement parameters
Pulse generation variables
Current shunt variables
Calibration parameters
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.
Page: 82 of 101
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