Keithley 2651A Reference Manual page 58

Section 2: General operation
Power measurements
Power calculations
Power readings are calculated from the sourced and measured current or voltage as follows:
P = V × I
Where:
P is the calculated power
V is the sourced or measured voltage
I is the measured or sourced 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 System
SourceMeter
Remote Commands
Hazardous voltages may be present on the output and guard terminals. To prevent electrical
shock that could cause injury or death, NEVER make or break connections to the Model 2651A
while the output is on. Power off the equipment from the front panel or disconnect the main
power cord from the rear of the Model 2651A before handling cables connected to the outputs.
Putting the equipment into standby does not guarantee the outputs are not powered if a
hardware or software fault occurs.
To perform power measurements:
1. Set source function and value. Press the SRC key to select the voltage or current source function
as required, then set the output voltage or current to the desired value. See Step 1 of
source-measure procedure
2. Press the LIMIT key, and set the voltage or current limit high enough for the expected voltage or
current across the DUT to be measured. See Step 2 of
(on page 2-24) earlier in this section.
3. Press the MEAS key to display power.
4. Turn on the output, then note the reading on the display. If necessary, press the TRIG key to
display continuous readings.
5. Turn off the output when finished.
Remote power programming
The following paragraphs summarize basic commands necessary for remote power programming and
also give a programming example for a typical power measurement situation.
2-36
Model 2651A High Power System SourceMeter® Instrument Reference Manual
®
instrument is already connected to the device-under-test (DUT) as explained in
(on page 5-1).
(on page 2-24) earlier in this section.
WARNING
Front-panel source-measure procedure
Front-panel
2651A-901-01 Rev. A / March 2011