What does the variable-speed motors and drives, copiers, fax machines causes?

A.
Harmonic distortion

B.
Electrical line noise

C.
Frequency variation

D.
None of the above

Explanation:
Harmonic distortion is a deformation of the normal electrical power waveform. It’s produced by variable-speed motors and drives, copiers, fax machines, switch-mode power supplies, and other kinds of nonlinear loads.
Incorrect Answers:
B: Electrical line noise can be triggered by radio frequency or electromagnetic interference from transmitters.
C: Frequency variation is the changes in the frequency stability of the 60-cycle AC generation is potentially damaging to sensitive electronic equipment.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 227-240.