Model 3761 10-Channel Low Current Multiplexer Card User's Manual
Section 5: Typical applications
3761-900-01 Rev. B
/
January 2018
5-5
The capacitor insulation resistance is calculated using the following formula:
Where:
•
R
INSL
= Insulation resistance of the capacitor under test
•
V
TEST
= The test voltage
•
V
MEAS
= Voltage measurement at the output of the 3761
•
R
DCHG
= Value of the discharge resistor
Be sure to select a series resistor value that maintains the 3761 test voltage specifications,
and select a V
EQ
value that minimizes the settling time of the indirect measurement.
Connecting multiple 3761 cards
Two output connectors on each 3761 card let you add multiple cards to expand the size of the
multiplexer by ten for each additional 3761. An additional relay isolates all circuitry on the card from
the outputs when all channels are open and closes when any channel closes. This isolation relay
configures itself automatically when assembling a test system using multiple 3761 cards.
The 3706A supports up to six 3761 cards, for a maximum of 60 low-current channels in a single
mainframe system. Up to sixty-four 3706A systems can be configured to provide 3,840 low-current
channels. See the
Series 3706A System Switch/Multimeter Reference Manual
, available on the
Keithley Instruments website
(
http://www.tek.com/keithley
), for multiple 3706A system configurations.
Leakage current specifications increase for each additional card enabled in a test system.
A 20-channel scanner system is shown in the next figure. In this configuration, you will connect one
output connector of the 3761 to a picoammeter, and the second output connector to an output
connector of a second 3761 card.
Use a SMA-male to SMA-male cable to connect the cards, such as a Cinch Connectors part
number 415-0038-012.
