S
AFETY
V
OLTECH
AC
I
NTERFACE
U
SER
M
ANUAL
98-072
ISS
7
PAGE
48
5.4. STRX
&
WATX
–
S
TRESS
W
ATTAGE
&
W
ATTAGE
The measurement accuracy is based on the chosen test conditions, and is given by:
𝐴𝐴
𝑇𝑇
=
𝐴𝐴
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀
+
𝐴𝐴
𝑉𝑉𝑂𝑂𝐶𝐶𝑀𝑀
+
𝐴𝐴
𝑃𝑃𝑂𝑂
where:
A
T
is the total accuracy (%)
A
MAGX
is the accuracy of the MAGX current measurement (%)
A
VOCX
is the accuracy of the VOCX voltage measurement (%)
A
PF
is the correction for power factor (%)
The accuracies of the MAGX and VOCX measurements are computed from the formulae in 5.2 and 5.3
𝐴𝐴
𝑃𝑃𝑂𝑂
= [1% + (0.001%
∗ 𝐹𝐹
𝑀𝑀
)
]
∗
√
1
− 𝑃𝑃𝐹𝐹
2
𝑃𝑃𝐹𝐹
where:
F
M
is the test frequency (Hz)
PF
is the power factor of the load
and:
𝑃𝑃𝐹𝐹
=
𝑊𝑊
𝑉𝑉𝐴𝐴
where:
W
is the measured power (W)
VA
is the product of MAGX and VOCX results
When performing either of these tests, the AT3600/AT5600 automatically applies the test voltage to the part
under test and checks that the voltage has stabilized before recording measurements.
The time that the voltage takes to stabilize 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/AT5600 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 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.
