Power Measurements - Keithley 2601B Reference Manual

Section 2: General operation
The 4-wire sensing method, as shown in the following figure (4-wire resistance sensing), minimizes or
eliminates the effects of lead resistance by measuring the voltage across the resistor under test with
a second set of test leads. Because of the high input impedance of the voltmeter, the current through
the sense leads is negligible, and the measured voltage is essentially the same as the voltage across
the resistor under test.

Power measurements

Power calculations
Power readings are calculated from the measured current and voltage as follows:
Where:
P is the calculated power
V is the measured voltage
I is the measured current
Basic power measurement procedure
If you need to customize the MODE key's standard watt-meter configuration, perform the following
steps to perform power measurements. The following procedure assumes that the Series 2600B is
already connected to the device under test (DUT) as explained in
48).
2-42
Series 2600B System SourceMeter® Instrument Reference Manual
Figure 13: 4-wire resistance sensing
DUT test connections (on page 2-
2600BS-901-01 Rev. B / May 2013