Sequoia Series 171
6.6.4 Harmonic Measurements
The MEASure and FETCh queries can return the amplitude and phase of up to the 50th harmonic of
voltage and current. They can also return the total harmonic distortion in the output voltage or current.
For example, to return readings for an individual harmonic component, use the following commands:
MEASure:CURRent:HARMonic:AMPLitude? <harmonic number>
MEASure:CURRent:HARMonic:PHASe? <harmonic number>
MEASure:VOLTage:HARMonic:AMPLitude? <harmonic number>
MEASure:VOLTage:HARMonic:PHASe? <harmonic number>
Harmonic numbers are related to the programmed frequency of output voltage. Queries sent with an
argument of 0 return the dc component. An argument of 1 indicates the fundamental frequency, 2
indicates the second harmonic, 3 indicates the third, and so on.
The maximum harmonic component that can be read is limited by the fundamental measurement
bandwidth, which is 19.53 kHz for a single phase configuration and 6.51kHz for three phase
configuration. An error is generated if a query is sent for a harmonic that has a frequency greater than
the bandwidth above. To return all the harmonic components with a single query, use the following
commands:
MEASure:ARRay:CURRent:HARMonic:AMPLitude? [<n>]
MEASure:ARRay:CURRent:HARMonic:PHASe? [<n>]
MEASure:ARRay:VOLTage:HARMonic:AMPLitude? [<n>]
MEASure:ARRay:VOLTage:HARMonic:PHASe? [<n>]
These queries always return 51 data values, from the dc component up to the numeric option field <n>
if present or the 50th harmonics. Any harmonics that represent frequencies greater than the
measurements bandwidth are returned as the value 0. To return the percentage of total harmonic
distortion in the output voltage or current, use the following commands:
MEASure:CURRent:HARMonic:THD?
MEASure:VOLTage:HARMonic:THD?
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