STPM01 datasheet(19/56 Pages) STMICROELECTRONICS

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STPM01

Theory of operation

19/56

When the BFR error is set, the computation of power is zero unless the FRS bit is set or the

Single Wire Mode operation is selected (see paragraph 5). In fact, the effect of the BFR bit

can be overridden by setting FRS configuration bit. It means that if FRS is set and BFR is

also set, all the energy computation is carried on as BFR was cleared.

In standalone mode, the MOP, MON and LED provide the energy information, their

operation is not affected by FRS bit, it means that when BFR is set they will be held low

regardless the FRS value.

When the line frequency re-enter the nominal band the BFR flag is automatically reset. This

BFR error flag is also assembled as part of 8-bit status register.

8.6

Single wire meter mode (only Rogowsky coil sensor)

STPM01 support Single Wire Meter (SWM) operation when working with Rogowsky Coil

current sensors. In SWM mode there is no available voltage information in the voltage

channel. It is possible that someone has disconnected one wire (live or neutral) of the meter

for tampering purposes or in case the line voltage is very stable, it is possible to use a

predefined value for computing the energy without sensing it.

In order to enable the SWM mode, the STPM01 must be configured with PST values of 4 or

5, (Tamper enabled-Rogowsky Coils). In this way, if the BFR error is detected, STPM01

Figure 16.

LIN and BFR signal

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