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MODEL 615
ELECTROMETER
OPERATION
SENSITIVITY
Switch
seeting
which permits
the use of
the smallest
value
rage
resistor.
The rsnge
resis-
tor
value
is equivalent
CO the reciprocal
of the
RANGE Switch
setting.
The input
voltage
drop across
the shunt
resistor
is indicated
directly
on the
Electrometer
digital
display.
NOTE
The SENSITIVITY
Switch
settings
permit
sn
input
voltage
drop af O.i,
1, 10, and 100
volts
for current
measuremenfs
in the
mrmsl
Mode.
on the LO-9 to 10-l'
AMPERES
settings
of the RAN E Switch,
the resistors
(109,
1010, and 101 E ohms) used have a volt-
age coefficient
uf .O*% per vale
(naminal).
1f the SENSITIVITY
Switch
is adjusted
far
a
100 v"lt
input
drop,
then a" additional
error
of 2% occurs
for the current
messure-
lS**t.
'rherefore
ie is reconrmended t"
select
The ZEN, CHECK Sutt~"
provides
a short
across
the feedback
of the Electrometer
Amplifier
to enable
zero adjustment.
Do not apply
a short
circuit
ecross
the
Electrometer
input
terminals
since
this
will
creete
""stable
amplifier
operation
4.
Adjust
the RANGE Switch
to increase
the Slec-
tr"meCer
seneitivity
for current
measurements.
5.
The full
range current
for
the Electrometer
is determined
by multiplying
the digital
readout
times
the RANGE Switch
setting.
The best accuracy
for current
measurements
is Obtained
by using
a
SENSITIVITY
switch
setting
which
permits
the use of
the smallest
value
range
resistor.
The range
cesis-
t"r
value
is equivalent
to the reciprocal
of the
RANGE Switch
settine.
The input
voltane
drop, across
ehe shunt
resistor
Is indicated
directly
on the
EiectromeLer
digital
display.
NOTE
the smallest
input
drop possible
to minimize
voltage
coefficient
errors.
d.
Fast mde Current
Weasurements
(for
current
be-
low 10-5 amperes).
1.
Set the front
panel
controls
es follows:
ZERO CHECK Button
RANGE Switch
LOCK
10-6 AMPERES
SENSITIVITY
Switch
FEEDBACK Switch
Fully
Councerclock-
wise
FAST
The source
resistance
of the circuit
eo be
measured
should
not
be Less
than
0.1
rimes
the range resistar
used since
adequate
feedback
voltage
cannot
be developed
at the
input
and zero stability
is adversely
af-
fected.
The range resistor
is the recip-
rocal
of the AMPERES range in ohms.
NOTE
TO make aff
graund measurements
refer
ta
Psragraph
2-6.
2.
Connect
the Model 6011 Triaxial
1"put
Cable
for measuring
an unknow" current
ae in 2-5,
c-2.
3.
unlock
the ZERO CHECK Sutton
t" make e mee-
surement
CAUTION
Foe measurement
of capacitor
leakage
cur-
rents
using
the Pest Mode, a very
stable
voltage
supply
must
be
used.
With a ~a-
pacitor
connected
across
the input,
the
electrometer
is exCrem*ly
sensitive
to
voltage
transients
with
a resultant
in-
crease
in readout
noise.
I
I
I
I
I
'f
I
I
I
I-
a-7
:
ME)WJ&NG
I
I
1 readout
I
1
I
X
__ _ _ _
I
SOURCE
I
I
AMMETER
I
L--------l
L------------l
1 = ' readout
R+Ri"
R
FIGURE 4.
Error
Due to Ammeter
Resistsnce.
0470
9
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