188.8.131.52 WATX and STRX Tests (External Source)
The accuracy for the measurement is given by:
AT = AMAGX + AVOCX + AP
AT is the total accuracy (%)
AMAGX is the accuracy for the current measurement (see MAGX specification) (%)
AVOCX is the accuracy for the voltage measurement (see VOCX specification) (%)
AP is the correction for the power factor (%)
AP = (1 + 0.0007 * FM) * (√(1 – PF2) / PF)
PF is the power factor of the load. (PF = W / VA)
FM is the measurement frequency (Hz)
When performing either of the above tests, the AT3600 automatically applies the test voltage to the part under test and checks that the voltage has stabilised before recording measurements. The time that the voltage takes to stabilise will vary with the source type used and the nature of the part under test.
In general (and especially for source types 'Programmable' and 'AT Output Transformer'), the AT3600 will record a measurement very quickly, (typically in less than 0.5 seconds) which is desirable in a production test environment.
If the measurement were to be recorded after a longer period of time under power, slightly different readings may be obtained due to self-heating effects in the part under test. This effect may be noticed when comparing results taken using different source types or with slower measurement systems.