STPM01 datasheet(49/60 Pages) STMICROELECTRONICS

Part #	STPM01

Description	Programmable single phase energy metering IC with tamper detection

PDF	60 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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49 / 60 page

STPM01

Theory of operation

Doc ID 10853 Rev 8

49/60

Equation 21

The RMS voltage value is obtained as:

Equation 22

For the apparent power another value is produced:

Equation 23

Multiplying Equation 20: and Equation 23: , the apparent power is produced:

Equation 24

Rogowsky coil

In this case we have:

Equation 25

while VRMS is calculated as in Equation 22: .

The apparent power is simple calculated multiplying Equation 25: and Equation 22: .

The DSP then performs the integration of the computed powers into energies. These

integrators are implemented as up/down counters and they can rollover. 20-bit output buses

of the counters are assigned as most significant part of energy data records. It is a

responsibility of an application to read the counters at least every second not to miss any

rollover.

RMS =

)

(

RMS

∫

)

(

⋅

′

∫

⋅

)

(

RMS

′′

∫

STPM01 Datasheet(PDF) 49 Page - STMicroelectronics