Source Impedance - Fluke 8502A Instruction Manual

8502A
Table
1-3. Specifications (Cont)
JNSTRUMEMT OPERATING CHARACTERfSTfCS
(Continued)
!
DC
Ratio
1
INPUT
IMPEDANCE
SOURCE IMPEDANCE
Ext Ref HI or
LO
>
10,000
relative to
Ohms
Resistive
Unbalance
(Ext
Ref
HI to LO)
<4
;
Guard*
or Sense
LO
j
1
Total Resistance Sense
LO from
either HI or
LO
<20
kCl
BIAS
CURRENT
OVERLOAD
(Ext Ref HI or LO)
i
Ext Ref
HI or
LO
relative to
Ohms Guard*
or
±180
volts
peak
,
127V rms
(relative to
Ohms
Sense
LO <5
nA Guard*
or
Sense LO)
X
(360V peak Hi
to
LO)
t
* Ohms
Guard
available through rear input
(-16
or
-17
Option)
NOISE REJECTION
Normal
Mode
Common
Mode,
All
Inputs Driven
Sense Input— Same
as
dc
volts
Ext Ref Input—
dc, line
frequency and 2x
line
freq-
uency
>100
dB
Sense input—
Same
as
dc
volts
Ext Ref Input—
Line
frequency and 2x
line
frequen-
cy,
75
dB
Settling
Time
Sense Input Fast
Filter
<
50
ms
to
0.001% of change
Sense Input Slow
Filter
<500
ms
to
0.001%
of change
Digitizing
Time
NOTE
The
Sense Input
is
measured
prior
to
measur-
ing
Ext Ref HI and
L
0.
Ext Ref Input-Each
input Hi
and
LO
90
ms
at
60 Hz
line
frequency
107
ms
at
50 Hz
line
frequency
Ext Ref
Calibration—1 2
ms
EXT REF VOLTAGE RANGE
Maximum
Ext Ref
Voltage = ± 40V
between Ext Ref
HI
and
LO
terminals,
providing
neither
ter-
minal
is
greater
than ±
20V
relative
to the
Sense
LO
or
Ohms
Guard
terminals.
Minimum Ext Ref Voltage =
±0.0001
V, or
(whichever
is
greater)
10
^
MAXIMUM
DISPLAY-
Ratio. Scaling or Offset
Mode
=
±1.00000 x 10^
in
all
Ranges
Sense Input
Approx.
Digitizing
Rdg. Rate
Time
60 Hz
4Va rdg/s
136 ms
1
Vi
rdg/s
536 ms
50 Hz
SVa rdg/s
1
Va.
rdg/s
162
ms
642 ms
60
Hz
4
samples/rdg 18
ms
50 Hz
4 samples/rdg 22
ms