Voltech AT3600 - Page 367

VOLTECH AT3600 USER MANUAL SPECIFICATION
SPECIFICATION VPN 98 - 024 PAGE 8.1.9.
MAGX TEST (EXTERNAL SOURCE)
The accuracy for measuring magnetising current using an external source is:
A
T
= A
R
+ A
C
+ A
I
+ A
OFF
+ A
ESI
+ A
SRCE
Where
A
T
is the total accuracy (%)
A
R
is the basic relative accuracy (%)
A
C
is the calibration accuracy (%)
A
I
is the correction for the current level (%)
A
OFF
is the error in the compensation measurement (%)
A
ESI
is the error in the current measurement from the source interface
(%)
A
SRCE
is the correction for the external source type (%)
The value of A
R
is given in the table in section 1.1 of this chapter
A
C
= 0.03% + (0.001 * F
M
)
A
I
= 0.03% + (0.0001 / I
M
) + (2 * I
M
)
A
OFF
= (0.76% + (0.001 * F
M
) ) * (0.3 / I
M
)
A
ESI
= 0.5%
A
SRCE
= 0.5% for manual / line supply
= 0.0% for analogue / amplifier and AT output transformer
F
M
is the test frequency (Hz)
I
M
is the measured current (A)
During a MAGX test, 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.