78M6610+LMU Data Sheet
Fundamental and Harmonic Calculations
The 78M6610+LMU includes the ability to separate low-rate voltage, current, active power, and reactive
power measurement results into fundamental and total harmonic components. These outputs can also be
used to track individual harmonics as well as the total value excluding the selected harmonic.
Register
Description
Time Scale
SINE
COSINE
Instantaneous voltage of the internal waveform generator
1 sample
VFUND_A
VFUND_B
Voltage content at specified harmonic
IFUND_A
IFUND_B
Current content at specified harmonic
PFUND_A
PFUND_B
Active Power content at specified harmonic
Reactive Power content at specified harmonic
Voltage content not at specified harmonic
Current content not at specified harmonic
Active Power content not at specified harmonic
Reactive Power content not at specified harmonic
QFUND_A
QFUND_B
1 interval
VHARM_A
VHARM_B
IHARM_A
IHARM_B
PHARM_A
PHARM_B
QHARM_A
QHARM_B
The HARM register is used to select the single harmonic to extract. This input register is set by default to
0x000001 selecting the first harmonic (also known as the fundamental frequency). This setting provides
the user with fundamental result and the total harmonic distortion (THD) of the harmonics
By setting the value in the HARM register to a higher harmonic, the fundamental result registers will
contain measurement results of the selected harmonic. Likewise, by setting the value in the HARM
register to a higher harmonic, the harmonics result registers will report the measurement of the remaining
harmonics. As an example, for any given accumulation interval, the magnitude of measurement result
IA_RMS would be the sum of IFUND_A and IHARM_A.
The SINE and COSINE registers are high-rate registers updated every sample with the instantaneous
value of the respective outputs from the internal Sine/Cosine generator. The referenced AC voltage
frequency serves as the reference for the internal waveform generator.
33
Rev 0
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
