1. Figure 1 in this chart shows the wave form of Phase A current. The ______ shape is due to harmonic currents typical of switching mode power supplies which are used in the majority of modern office automation equipment.

Fill in the blank ______

2. Read THIS article. Then fill in the blank. A new range of active harmonic _______ aims to set new standards in fight against distortion and corruption of the mains electricity supply caused by back-harmonics from equipment.

 Fill in the blank ______

3. Measurements on electrical distribution systems powering nonlinear loads usually disclose the presence of what two kinds of harmonics as discussed in this ECM article?
 http://www.ecmweb.com/ar/electric_harmonic_current_voltage

4. Total harmonic distortion (THD) is a measure of the amount of distortion produced as current flows from the power line. This line current can flow at the fundamental frequency (60 Hz in the U.S.) or it may be combined with odd harmonic currents (multiples of the fundamental) such as 180 Hz (third harmonic), 300 Hz (fifth harmonic), and 420 Hz which is the _____ harmonic.
Click HERE for the source document. It is too large for this space.

Fill in the blank______