Maxim Integrated 78M6612 M-API Library - Manual (Page 6)

78M6612 M-API Library User Guide UG_6612_036
6 Rev. 1.00
1.2 Library Measurement Equations
The integrated Compute Engine (CE) accumulates the raw samples from the ADC and provides to the
80515 MPU the critical *atomic measurements needed to derive all other data. This consists of RMS
Voltage, Voltage Sag Status, and AC Line Frequency data as well as RMS Current, Active Power, and
Reactive Power for each outlet. The MAPI library provides the application developer with two equation
options for processing the atomic values before updating the libraries output data registers. One equation
option is defined as “Narrowband” (NB) and the other is defined as “Wideband” (WB).
When using NB equations; RMS Voltage, Active Power, and Reactive Power data is provided by
the CE and used to derive RMS Current, Apparent Power, and Power Factor in the MPU for each
outlet. Harmonic content is not included in the reported current measurement.
*Voltage (V
RMS
) =
√∑v(t)2
Current (I
RMS
) = S/V
RMS
*Active Power (P) =
∑ (i(t) * v(t))
*Reactive Power (Q) =
∑ (i(t) * v(t) shift 90º)
Apparent Power (S) =
√(P 2
+ Q
2
)
Power Factor (PF) = P/S
When using WB equations (recommended); RMS Voltage, RMS Current, and Active Power data
provided by the CE is used to derive Reactive Power, Apparent Power, and Power Factor in the
MPU for each outlet.
*Voltage (V
RMS
) =
√∑v(t)2
*Current (I
RMS
) =
√∑i(t)2
*Active Power (P) =
∑ (i(t) * v(t))
Reactive Power (Q) =
√(S 2
– P
2
)
Apparent Power (S) = V
RMS
* I
RMS
Power Factor (PF) = P/S