Fluke 8506A Instruction Manual page 52

8506A
V
AC
measurements. This
setting
minimizes input
capacitance.
NOTE
The
Ohms
Selector has
no
affect
on
rear
inputs.
Rear
inputs are dedicated
in
a four-
wire configuration.
3.
The Guard
Selector
is
disengaged
(out) for
non-
critical
measurements.
Refer
to
Measurement
Terminals
and
Controls
for
a
full
description of
guarding
when
this
selector
is
engaged
(in).
The
Guard
Selector has
no
affect
on
the rear inputs.
2-149.
Measurement
parameters,
mathematic
operations,
and
special
operations can be
specified prior
to or
during measurements. These parameters and
operations can be applied
to
measurements
in
any
function,
with
the
following
exceptions:
1 .
External Reference
mode
is
not available
in
any
of
the
V
AC
functions
(HI
ACCUR, NORMAL,
or
ENH'D).
2.
Averaging
is
not
available
in
any
of
the
V
AC
functions
(HI
ACCUR, NORMAL,
or
ENH'D).
The
AVG
pushbutton
may
be used
in
the
V
AC
functions
to
enable
an
extended
display resolution.
2-150. Front panel
programming
of the multimeter
is
best
accomplished
in
a sequential manner. This sequence
is
fully
explained
in
Figure
2-3. Often, only
measurement
parameters need be
specified.
Programming
of
any
mathematic
operation requires consideration of
mathematics
already
in effect.
2-151. Refer
to
Figure 2-5
for
an
outline of
measurement
connections. Also
refer to
Measurement
Terminals and Controls
earlier in this
Section.
2-152,
Measurement
Instructions
2-153.
AC VOLTS (THERMAL
TRUE-RMS)
NOTE
It is
recommended
that
all
ac volts
measurements
be
made
with
the the
Ohms
Selector
in
the
engaged
( in )
position
to
minimize
input capacitance.
2-154.
Thermal
ac-ac transfer
measurements can
be
made
using the
Thermal
True-RMS
Converter Module.
Select the
mode
of operation
desired, as determined by
the
degree of accuracy and
speed
required.
2-155.
AC
Volts
Normal
Mode
(V
AC NORMAL)
2-156.
Use
the following
procedure when measuring
ac
volts
with the
normal
mode
of the
Thermal
True-RMS
Converter:
1.
Push
the
V
AC
NORMAL
button
(NORMAL
annunciator
lights).
2.
The multimeter assumes autoranging
(beginning
at
the
500V
range)
when
a
V
AC
function
is
selected.
However,
if
a
V
AC
function
was
previously
in effect,
the previous range
is
retained as the starting point
for
any
possible
autoranging.
3.
Select the
filter
by pushing
the
FILTER
button
if
the frequency of the input signal
is
<40
Hz.
(The
accuracy of
the
instrument
is
degraded
if
the
filter
is
selected for higher input frequencies).
4.
Connect
the
ac voltage
to the
HI and
LO
SENSE INPUT
terminals).
2-157.
AC
Volts
Enhanced
Mode
(V
AC ENH
!
D)
2-158. Use
the following procedure
when
measuring
ac
volts
with
the
enhanced
mode
of the
Thermal
True-RMS
Converter:
1.
Push
the
V
AC
ENH'D
button
(ENH'D
annunciators
light).
2.
The
multimeter assumes autoranging
(beginning
at
the
500V
range)
when
a
V
AC
function
is
selected.
However,
if
a
V
AC
function
was
previously
in
effect, the previous range
is
retained as the starting point
for
any
possible
autoranging.
3.
Select the
filter
by pushing
the
FILTER
button
if
the
frequency
of the input signal
is
<40
Hz. (The
accuracy of
the instrument
is
degraded
if
the
filter
is
selected for
higher input
frequencies).
4.
Connect
the
unknown
ac voltage
to
the
HI and
LO SENSE INPUT
terminals.
5.
The
initial
high accuracy
measurement
requires
six seconds.
The
rms
voltage
should
be displayed
within
0.5
second
of the
completion
of
this initial
high accuracy reading
and updated
every
0.5
second
thereafter.
6.
A
new
high accuracy measurement
can
be
commanded
at
any time by pushing
the
ENH'D
button
again. After
six
seconds,
the
SAMPLE
annunciator
flashes
briefly
and
0.5
second updates
resume.
NOTE
The
Thermal
True-RMS
Converter
automatically takes a
new
reading
to establish
a
new
correction factor
if
the
range changes
(either
manual
or autorange), the
filter
setting
changes
,
or the
difference
between
the reading
and
the
present correction factor
is
^/%.
2-
30