Question: 

How to power a Fluke 177x or Fluke 174x from the measured line?

Answer: 

When a power quality analyzer or logger is installed on a network for a logging session, the battery life time is not sufficient in most cases.
The unit can be powered from a receptacle with a power cord, or from the measured line.

This video shows how to power the Fluke 1770 from the measured line, but is also applicable to Fluke 1740.

The products can be powered from phase-neutral, or phase to phase, as long as the voltage is between 100 and 600 Volt.