Tektronix SPG8000 Technical Reference page 177

SYSTEM button menu
Passed/Failed. Shows the status of the previous load test for the supply currently
configured to be the backup (standby) supply along with the date (year, month,
day) and time (HH:MM:SS) of the last test.
Press ENTER to start test. Use this menu item to initiate the load test. During
the test, a status message appears. After the test is complete, the test results are
displayed. For example, if Power Supply 2 is configured to be the backup supply,
the message "Pass: Backup supply PS2 loadtest" is displayed. Press the BACK
button to exit the load test.
NOTE.
If you have only one power supply installed that is connected to power, an
error message will appear if you attempt to run this test.
If you attempt to run the load test immediately after changing the preferred supply
configuration or if you rerun the test immediately after running the test a first
time, an error message may appear stating that the load needs to cool down
before the test can be run. The error message includes an estimate of the time
needed for the load to cool down before you can run the test. An example message
in this situation is "Error: cooldown, 1 min 40 sec left."
SPG8000 Technical Reference 165