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MOOEl 70617067A
CHANNEL
UNDER
OUTPUT
TEST
--
H,
,o
GUAflD
H>
,o
T
L~
JIU
MOOELZJOj
POWER
!
SUPPLY
j
;LO
,H1
ELECTRO- '
MEIER
1614 OR 6191 :
SET
TO
A.MPS
':LO
i
Figure 7. Channel Isolation Test Set Up
3.5 INPUT ISOLATION, COMMON MOOE
A. This test measures the leakage resistance between signal lines and power
line ground. Set up the test circuit shown in Figure 8.
B. Short the input HI and LO terminals of each channe1 with a short piece of
solid copper wire. Do not connect the channels together, just short the HI
and LO terminals.
C. Insert the Model 7057A into the mainframe and set the Model 705 to the
Channel mode, Channel
2
and
the Step
mode.
D. Set the electrometerto Amps and program the Model 230 to output 100V.
Take the electrometer out
of ZERO CHECK.
E.
Take the reading on the electrometer. The reading should he less than
1
x
10-
5
A. Using Ohm's Law calculate the isolation {leakage resistance).
For example: R=E/I =
100V/1
x
10-
5
A =
10
7
!l. Due to the
capacitance of the circuit, the offset current
may
be high
until
the
capacitance is charged up. Wart until the readings settle out.
F. Manually scan Channels 2 through 10 repeating step D and E for each
channel.
MODEL 70!V7057A
CHAflJNEL UNDER
TEST
HI
,0
GUARD
ELECTRO
METER
HI
iSETTO
AMPS!
614 OR
"'
,o
MOOEL
""
HI
POWEF!
SUPPLY
LO
Figure 8. Common Mode Isolation Test Setup
22
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