STPM01_11 STMICROELECTRONICS [STMicroelectronics], STPM01_11 Datasheet - Page 25
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STPM01_11
Manufacturer Part Number
STPM01_11
Description
Programmable single phase energy metering IC with tamper detection
Manufacturer
STMICROELECTRONICS [STMicroelectronics]
Datasheet
1.STPM01_11.pdf
(60 pages)
STPM01
8.10.1
Figure 18. Timings of tamper module - Primary channel selected
Figure 19. Timings of tamper module - Secondary channel selected
MUX
INH
Tamper power integrators
Cycles
The tamper circuit works if the energies associated with the two current channels are both
positive or negative, if the two energies have different sign, the tamper is on all the time
however, the channel with the associated higher power is selected for the final computation
of energy.
In single wire mode, the apparent energy rather than the active is used for tamper detection.
When internal signals are not good enough to perform the calculations, i.e. line period is out
or range or ΔΣ signals from analog section are stacked at high or low logic level, or no load
condition is activated, the tamper module is disabled and its state is preset to normal.
Detailed operational description
The meter is initially set to normal state, i.e. tamper not detected.In this condition the
primary channel is selected for final integration of energy. In such state the values of both
load currents should not differ more than the accuracy difference of the channels does.
Sixty-four periods of line voltage is used as a tamper checking period.
After 24 periods of line voltage two internal signals MUX and INH are changed in order to
enable secondary current channel and to freeze the last power and RMS values of primary
current channel. The following 16 periods of line frequency are used for tamper detection
integration. During this gap, the final energy calculation does not use the signal from
selected channel but the frozen values.
Four line periods after the INH switch, the integration of power from secondary current
channel is started and lasts four periods. Additional four line periods later MUX signal is
switched back to primary current channel and the integration for tamper detection is started.
The timings of MUX and INH signals are shown in
When the secondary channel is selected to be integrated by the final energy integrator, the
MUX and INH signals change according to
This means that energy of four periods from secondary channel followed by energy of four
periods from primary channel is sampled within the tamper module. From these two
Ch 1
24
Doc ID 10853 Rev 8
4
Ch 2
B
4
4
Figure 19
Ch 1
A
4
Figure 18
below.
below.
24
Ch 1
Theory of operation
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