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Section
III
Model
3455A
Figure
3*2.
Ohmmeter
Measurement
Connections.
volt full-scale
to
1000
volts
full-scale.
Measurement
results
are presented
in
5-1/2
digits
during
normal
operation or
in
6-1/2
digits
when
the
34S5A
is
set
to the
High
Resolution
mode.
All ranges except the
1000
volt
range
have
50^
overrange
capability
and
are
overload
protected
from
input voltages
up
to
±
1000
volts.
Input
resistance
in
the
dc
function
is
greater
than
10'^
ohms
on
the
.1
V,
1
V,
and
10
V
ranges
and
equal
to
10
megohms
on
the
100
V
and
1000
V
ranges.
Refer
to
Table
1-1
for
DC
Accuracy
specifications.
3-12.
Rnistancs Maasuramant.
3-13.
The Model 3455A
measures
resistance
from
1
milliohm
to 15
megohms
in six
ranges extending
from
.1
kilohms
ful
scale to
10.000
kilohms
full
scale.
Measure-
ment
results
are presented
in
5-1/2
digits
during
normal
operation
or
in
^1/2
digits
when
the
3455A
is
set
to the
High
Resolution
mode. The
only exception
is
that
the
.1
V
range can only take
a
measurement
in
the 5-1/2
digit
mode.
Resistance
may
be
measured
in
"4-WIRE"
con-
figuration for
optimum
accuracy or
"2-WlRE"
con-
figuration
may
be
selected
for
measurement
conve-
nience.
Figure
3-2
shows
proper connections
for
making
resistance
measurements.
The
nominal
output
signal
current
on
the
.1
kilohm,
I
kilohm and
100
kilohm
ranges
is
.7
mA.
The
nominal output
current
on
the
1000
kilohm and
10,000
kilohm
ranges
is
.7
microamp.
Maximum
output
voltage
is
limited to
less
than
5
volts
on
all
ranges.
Refer
to
Table
1-1
for
ohm
accuracy
specifications.
3-14.
AC
Voltage
Meaiuremont.
volts
RMS.
Readings taken
in
the ac function are
display
in
the
5-1/2
digit
mode
only.
Input
impedance
of both
convertors
is
2
megohms
in
parallel
with
<
75
pF
for rear
terminal input
and
<
90
pF
for front
terminal
input. In
addition to the
normal
ac
volts
func-
tion,
the
3455A
also
has
a
fast
ac
volts function.
The
fast
ac function has
a
faster
ac reading
rate
than
the nor-
mal
ac
function.
3-16.
The
frequency response of
the true
RMS
conver-
tor
is
from
30
Hz
to
1
MHz
in
the
normal
ac
volts
func-
tion
and from
300
Hz
to
1
MHz
in
the
fast
ac
volts
func-
tion.
Both
ac
signals
or
ac plus
dc
signals (ac signals
superimposed
on
a
dc
level)
can
be
measured by
the
true
RMS
convertor. Selection
of
the ac or
ac
-f
dc
inputs
are
chosen by a
switch located
behind
the
rear
panels
reference
cover.
Refer
to
Table
1-1
for
accuracy
specifications
of each
ac
mode.
3-17.
The
frequency response of
the
average
converter
is
from
30
Hz
to
250
Hz
in
the
normal
ac
volts
function
and from 300
Hz
to
250
kHz
in
the
fast
ac
volts
func-
tion.
Only
ac
signals
(no dc
component)
can
be
measured by
the
average
converter.
Refer
to
Table
1-1
for
accuracy
specification
of each
ac
mode.
3-18. In
order
to get
accurate ac readings
(especially
with high voltage inputs
at
high
frequencies), the
low
in-
put terminal
(front
and
rear)
should be connected
to the
guard
terminal
(front
and
rear).
Refer
to
paragraph
3-39
for
guarding information.
3-15.
The
-hp-
Model 3455A
offers a
choise
of
true
RMS
(standard
unit)
or average responding
ac conver-
NOTE
tors
(Option
(X)l).
^th
methods measure
ac
voltages
from
10 microvolts
to
1000
volts in
four ranges
exten-
The
front
pane!
guard pushbutton
applies
ding
from
1
volt
to
1(XX)
volts
ranges. All ranges,
except
only
for
front panel
inputs.
Be
sure
to
wire
the
1000
volts
range,
have
50%
overrange
capability
and
rear
panel guard connections
yourself,
if us-
are protected
from
input voltage
components up
to
1000
ing the rear
pane!
input
terminals.
3-2
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