Fluke 8024B - Page 48

8024B
your
8024B
are
different
from
both
the
Alumel
and
the
Chromel
(Figure
2-18,
Part
C)
which
would
seem
to
add
a
third
junction
to
the
loop.
But,
remember
there
is
no
current
or
voltage
in
a
thermocouple
loop
if
both
junctions
are
at
the
same
temperature.
The
:sothermal
characteristics
of
the
special
termination
unit
for
John
Fluke
thermocouples
insures
that
the
two
junctions
at
your
DMM
areat
the
same
temperature.
This
leaves
the
original
circuit
as
shown
in
Figure
2-18,
Part
A.
If
you
are
going
to
connect
your
own
K-
type
thermocouple,
use
a
John
Fluke
Model
Y8104
Thermocouple
Termination
Unit
(see
Section
6
for
details).
2-73.
Monitoring
More
Than
One
Thermocouple
2-74.
You
can
use
your
8024B
to
monitor
more
than
one
thermocouple
--
even
thermocouples
that
are
permanently
mounted
in
your
system.
If
your
present
K-type
thermocouples
are
permanently
mounted
in
a
system
and
have
individual
remote
reading
stations,
you
can
attach
your
present
K-type
thermocouple
quick-connect
toa
John
Fluke
Model
Y8104
Thermocouple
Termination
Unit
via
K-type
thermocouple
wire
(Figure
2-
19).
Then
plug
the
Y8
104
into
your
80248,
and
carry
the
meter
and
thermocouple
quick-
connect
assembly
from
station
to
station
reading
the
various
temperatures.
If
your
thermocouples
are
routed
toa
centralized
point
(Figure
2-20),
use
one
or
more
John
Fluke
Model
2161A
Multipoint
Selectors.
Connect
the
last
2161A
to
your
8024B
via
a
Y8104
Thermocouple
Termination
Unit
and
select
the
thermocouple(s)
you
want
to
read.
9-75.
Leakage
Tester
2-16.
The
200
nS
conductance
range
effectively
extends
the
resistance
measurement
capability
of
the
8024B
(up
to
10,000
MQ)
to
the
point
where
it
can
be
used
to
provide
useful
leakage
measurements
on
passive
components.
For
example,
you
can
detect
leaky
capacitors,
diodes,
cables,
connectors,
printed
circuit
boards
(pcbs),
etc.
In
all
cases,
the
test
voltage
is
<SV
de.
2-77.
Leakage
testing
on
purely
resistive
components
such
as
cables
and
pcbs
is
straightforward.
Select
the
200
nS
range,
install
the
test
leads
in
the
V/Q/S
and
COMMON
input
terminals,
connect
the
leads
to
the
desired
test
points
on
the
unit-under-
test,
and
read
leakage
conductance.
If
an
overrange
OcCcUTS,
select
the
resistance
range
that
provides
on-scale
reading.
NOTE
Under
high
humidity
conditions
(>80%)
conductance
measurements
may
be
in
error.
To
ensure
accurate
measurement,
connect
clean
test
leads
to
the
8024B
and
(with
the
leads
open
)
read
the
residual
leakage
in
nanosiemens.
Correct
subsequent
measurements
by
subtracting
the
residual
from
the
readings.
(Fingerprints
or
other
contamination
on
the
pcb
may
also
cause
residual
conductance
readings.
)
2-78.
DIODES
9-79.
Diode
leakage
(IR)
tests
require
that
the
diode
junction
be
reverse
biased
when
being
measured.
This
is
accomplished
by
connecting
the
diode’s
anode
to
the
COMMON
input
terminal
and
its
cathode
to
the
V//S
input
terminal.
Leakage
can
then
be
read
in
terms
of
conductance.
In
the
event
of
an
overrange,
select
the
resistance
range
that
provides
on-scale
reading.
2-31