EXFO FTB-635 Wideband Copper and DSL Test Module - Manual (Page 253)

Noise Tests
Copper and xDSL Tests 245
Power Influence Test
Summary
Power Influence is a classical and common measurement to check the
level of influence of power lines on voice circuits. The level of influence is
mostly affected by how long the power line runs parallel with the phone
line, but also the distance between the power and phone lines, and
balance of the pairs/cable. The presence of harmonics can indicate
problems or faults in the power distribution plant, which may only be
resolved in some cases by the power company. With the deployment of
higher speed services over DSL, the upper harmonics of the power
distribution are of more concern, and can reach as high as 375KHz, well
into DSL frequencies. Good balance and a well maintained sheath/shield
(bonds and grounds) are the key elements in minimizing the effect of
Power Influence on cable pairs.
Summary tab displays the pass/fail status of the tests executed. Refer
Copper Tests: Result Summary on page 291 for more information.