2000I & 2000M Instrument’s User Guide, Revision B
50
In most circumstances, the use of a tightly twisted pair of 28AWG wires is
recommended, as this both reduces the effects of thermal E.M.F. voltages
and achieves the close coupling required to reject interference.
Route all line wiring and any digital wiring as distant as possible from the
analog instrument connections (particularly computer interface and net-
working cables). For routing distances greater than three feet, use a
shielded cable or twisted pair to connect to the terminals
.
When the instrument is driving a load, consider the impedance of the wiring.
With a 10mA load, the cabling will drop l
μ
V for every 0.1m
Ω
of cable resistance.
Check that sufficient wire gauge is used and that the connections to the terminals
are clean and tight.
Ensuring Stable Current Connections
The considerations for low-level DC currents are similar to those for voltages, but
thermal E.M.F. voltages and lead resistances have no effect on performance. The
primary effects in this mode of operation are those of interference, cable leakage
and dielectric storage.
The effect of interference on low level currents is far more pronounced
than for DC voltages.
For high performance use tightly coupled twisted pairs and/or shielded
cables. When using shielded cables, note that while electro-magnetic inter-
ference is essentially eliminated, the capacitive injection is eliminated in
the center conductor of the cable (only). The twisted pair balances the in-
jection thus has less effect.
Some instrumentation has far different noise rejection characteristics in
one terminal than the other—commonly, one terminal is the virtual earth
of an amplifier. Reverse the connections to find the best orientation, par-
ticularly when shielded cables are being used.
Summary of Contents for Xitron 2000 Series
Page 1: ...USER GUIDE 2000 Family DC Temperature Source Instruments...
Page 2: ......
Page 18: ...2000I 2000M Instrument s User Guide Revision B 18...
Page 42: ...2000I 2000M Instrument s User Guide Revision B 42...
Page 47: ...Using the Memory Options 47...
Page 60: ...2000I 2000M Instrument s User Guide Revision B 60...
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Page 92: ...2000I 2000M Instrument s User Guide Revision B 92...
Page 95: ...Appendix B General Specifications 95...
Page 97: ...Password Page 97...