You could spread the harmonic pulses around some more (in terms of phase angle timing) if you operate some of the PCs off of 208V (phase to phase). PC power supplies usually have 120/240 selector switches. What this can do: Say most of the PCs are operating off of 3 phases of 120V. At phase angle 0, 1/3 of the PCs draw a spike of current off phase A, and return it on the neutral. Then at 120 degree phase angle PCs on phase B draw a spike of current, and return it on the neutral. Now if you connect a PC (after setting the power supply to 240V setting) across phase A and B for 208V it will draw, at phase angle 150, a current spike current and return it from phases A and B, and the neutral sees nothing. This is in between times of PCs on phase A and neutral, B and neutral and C and neutral are drawing their current spikes. This off loads the neutral some, and also should make the power company a little happier.
[This message has been edited by wa2ise (edited 10-12-2005).]
