Test Fixtures - Keithley 2461 Reference Manual

Model 2461 Interactive SourceMeter® Instrument Reference Manual Section 2: General operation
Minimizing the effect of lead resistance with 4-wire testing
The 4-wire sensing method, shown in the following figure, minimizes or eliminates the effects of lead
resistance. The effects of lead resistance are minimized by measuring the voltage across the resistor
under test with a second set of test leads. The current through the sense leads is negligible, and the
measured voltage is essentially the same as the voltage across the resistor under test. Note that the
voltage-sensing leads should be connected as close to the resistor under test as possible to avoid
including the resistance of the test leads in the measurement.
Figure 64: Model 2461 4-wire resistance sensing
Sense current is negligible, therefore
Measure resistance is

Test fixtures

A test fixture can be used to house a device or test circuit. The test fixture can be a metal or
nonconductive enclosure, and is typically equipped with a lid. When the test fixture is correctly
connected using the interlock, the output of the Model 2461 will be less than ±42 V when the lid of
PEAK
the test fixture is opened.
You mount the test circuit inside the test fixture.
2461-901-01 A/November 2015 2-95