Measurement Procedure; General - QuadTech 1865 Instruction Manual

A three-wire guarded connection is necessary to measure resistance between two points
in the presence of resistance from each of these points to a third point. Refer to
paragraph 3.6 for a discussion of guarded measurements. The guarded measurement may
require different grounding techniques depending on the expected impedance of the
DUT.
DUT DUT
+ - + -
GND GRD GND GRD
a) DUT Grounded b) DUT Ungrounded
+ Unknown and - Unknown are connected to DUT
GUARD to DUT Guard Point
+ Unknown shorted to GND
OR
GUARD shorted to GND
Figure 2-4: Three-Wire Guarded Connection (Grounded or Ungrounded)
2.5

Measurement Procedure

2.5.1 General

There are two basic measurement modes of operation, auto and manual. In the automatic
mode the test cycle is sequenced automatically through four phases, charge, dwell,
measure and discharge in accordance with user programmable times. This is the
preferred measurement mode, especially when the approximate resistance value is
unknown, since the 1865 instrument employs an auto ranging technique. The automatic
mode would generally be used in a production environment where measurements are
repetitive and setup conditions have been previously established. For the sake of
reducing measurement time, when making repetitive measurements, a particular range
may be locked in, in place of auto ranging.
Page 32 of 87 Operation