Fluke 8050A Instruction Manual page 32

OPERATION
RESISTANCE
MEASUREMENT
Es
=
Source
voltage
Ri
—
Load resistance
+
Source
resistance
Im
=
Measured
current {display reading
in
amps)
Eb
=
Burden
voltage (calculated)
Eb
current [(200/current
range
in
mAj
+.35
EXAMPLE:
Es
=
15V
Ri
-
100
kfi
Im
=
148,51 {,14851
mA)
Eb
=
148.51
X 10
-®
X [(200/.2)
+
.35]
=
148.51 X
10-®
X
1000.35
=
148,56
mV
Max.
error
in
% =
100
x
(148.56
mV/(15V
- ,14856V)]
=
1.0003%
Add
this to
the range spec, accuracy;
Max.
error
in
%
=
1.0003% ±(.2%
+
2 digits)
Max.
error
in
A
=
(148.56
mV
x 148.51 ;UA)/(15000
mV
-
148.56
mV)
ERROR:
=
1,486
tik
Error
in
%
100
x
Eb/{Es
-
Eb)
Add
1.486
aA
to
the reading
for correct current
Error
in
A =
{Eb
x lm)/(Es
-
Eb)
2-58.
TEST LEAD COMPENSATION
2-59.
When
measuring low
resistances
(less
than 2000)
the effect of
test
lead
resistance
may
add
a
significant
error.
This
error
may
be compensated
for
by
using the
relative
function of
the
8050A. Use
the following
procedure
to
compensate
for
test
lead
resistance.
1
.
Setup
the
8050A
as
shown
in Figure
2-5, steps
1
through
3.
2.
Short
the
test
leads
together (press the
test
leads
together firmly)
and
set the
RELATIVE
switch
to
ON.
3.
Disengage
the
test
leads
and
proceed with low-
level resistance
measurements. The
resistance
of the
test
leads
will
be
subtracted
from
the
readings of subsequent
measurements.
2-60.
RESISTANCE COMPARISONS
2-61.
When
one
resistance
value
is
needed
for several
measurements
(e.g.
sorting
resistors
to find a
matched
pair)
the
relative
function of
the
8050A
can
be
used
to
simplify the process.
The
following procedure
is
an
example
of
how
the
relative
function
may
be used
to
match
resistors:
1.
Select the
kO
function
on
the 8050A.
4.
With
the
resistor
value
still
displayed,
set
the
RELATIVE
switch to
ON.
5.
Measure
the
other
resistors.
Choose
the
resistor
with the
least
deviation
from
the resistor
first
measured.
2-62.
Conductance Measurement
2-63.
The
following paragraphs
contain additional
information
on and measurement
techniques
for
conductance measurements.
2-64,
HIGH RESISTANCE
MEASUREMENTS
2-65.
The
conductance
function of the 8050A
can be
used
to
measure high
resistive
(low leakage) components
(diodes
and
capacitors) while minimizing
noise problems.
The two conductance
ranges, 2
mS
and
200 nS, can be
used
for
making
resistance
measurements from 5000
to
10
MO
and
5
MO
to
100,000
MO.
2-66,
LEAKAGE RESISTANCE MEASUREMENTS
2-67.
Use
the
standard conductance
function
for
leakage
testing
on
purely
resistive
components
(e.g.,
cables
and
pcb's).
Remember
to
zero the display reading
with the
relative
function before taking conductance
measurements.
NOTE
2. Select
an appropriate range
for the resistance Under
high humidity
conditions, fingerprints
being matched.
and
other residual surface contaminants can
create their
own
leakage paths. Use
clean
test
3.
Measure
the
resistor.
leads to
minimize
the
effect
of leakage paths.
2-14