Question : Problem: Line conditioner for "dirty" power

Customer gets lots of "dirty" power from power company but already has a dual conversion online UPS to protect them. Customer feels that this is not enough and has seen tv shows that have talked about something before the UPS in the electrical room (something about filtering harmonics) that have been placed in large business installations that is protection before it reaches the UPS. (not a generator)
Filtering harmonics may not be the right solution but I would like to start there.

I am hoping to hear from people that are electrical engineers (if possible) or have had extensive electrical work or have seen large installations where the above scenario has been used.

Answer : Problem: Line conditioner for "dirty" power

I'm not an electrician, but since you typically install these for the whole building, it would go before the UPS.  Three-phase power has three wires plus a ground, so those are the four connections.

I haven't installed these, so I can't comment on whether one brand is better than another.  You may want to wait for someone with actual experience to comment on this.