Service Information
4-8
4.3.7 Isolation tests
These tests check the leakage resistance (isolation) between
all HI and LO terminals and from HI and LO terminals to
chassis ground. In general, the test is performed by applying a
voltage (100V) across the terminals and then measuring the
leakage current. The isolation resistance is then calculated as
R = V/I. In the following procedure, the Model 6517 functions
as a voltage source and as an ammeter. In the resistance (R)
function, the Model 6517 internally calculates the resistance
from the known voltage and current levels, and displays the re-
sistance value.
Perform the following steps to check isolation:
1. Connect a 4” length of Teflon-insulated #22AWG
stranded wire to every HI and LO terminal on the scan-
ner card (both inputs and outputs). Mark the free end of
each wire so you can identify wires when the scanner
card is installed.
2. With the power off, install the scanner card in the multi-
meter.
3. Turn on the Model 2001 power.
4. Turn on the Model 6517, and allow the unit to warm up
for one hour for rated accuracy.
5. With the V-Source in standby (OPERATE indicator off)
and zero check enabled (Zero Check displayed), config-
ure the Model 6517 to make >1G
Ω
resistance (R) mea-
surements using a V-Source value of +100V. Refer to the
Model 6517 User’s manual for details on electrometer
operation.
WARNING
The following steps use high voltage
(100V). Be sure the V-Source is in stand-
by before making connection changes.
6. With the Model 6517 in standby, connect the electrom-
eter to OUT A HI and LO terminals of the scanner card,
as shown in Figure 4-4.
7. Close channel 2 using the CHAN key (see paragraph
4.3.5 for details).
8. On the Model 6517, disable zero check, and press OPER
to source 100V.
9. After allowing the reading on the Model 6517 to settle,
verify that the reading is >1G
Ω
(10
9
Ω
). This measure-
ment represents the isolation resistance between the HI
and LO terminals of channel 2.
10. Place the Model 6517 in standby, and enable zero check.
11. Repeat steps 7 through 10 for channels 3 through 10. Be
sure that the channel under test is closed.
12. With the Model 6517 voltage source in standby, connect
the electrometer to the HI terminals of scanner card
channels 2 and 3, as shown in Figure 4-5.
13. Close channel 2 using the CHAN key.
14. On the Model 6517, disable zero check, and press
OPER to source 100V.
15. After allowing the reading on the Model 6517 to settle,
verify that the reading is >1G
Ω
(10
9
Ω
). This measure-
ment represents the isolation resistance between the HI
terminals of channels 2 and 3.
16. Place the Model 6517 in standby, and enable zero check.
17. Repeat steps 12 through 16 to measure isolation resis-
tance between the channel 2 HI terminal and channels 4
through 10 HI terminals. Be sure that the electrometer is
connected to the HI terminals of the two channels being
tested, and that channel 2 is closed.
18. Repeat steps 12 through 17 for the LO terminals of
channels 2 through 10. Be sure the electrometer is con-
nected to the LO terminals of the two channels being
tested, and that channel 2 is closed.
19. With the electrometer voltage source in standby, con-
nect the electrometer to channel 2 HI and chassis
ground, as shown in Figure 4-6.
20. Program the Model 2001 to close channel 2.
21. On the Model 6517, disable zero check, and press
OPER to source +100V.
22. After allowing the reading on the Model 6517 to settle,
verify that it is >1G
Ω
(10
9
Ω
).
23. Put the electrometer in standby, and enable zero check.
24. Repeat steps 19 through 23 for channels 3 through 10.
One electrometer lead should be connected to the HI ter-
minal of the channel being testing, and the other lead
should be connected to chassis ground.
25. Repeat steps 19 through 24 for channels 2 through 10
LO terminals. One electrometer lead should be connect-
ed to the LO terminal of the channel being tested, and
the other lead should be connected to chassis ground. In
addition, channel 2 should be closed.
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