A light-duty commercial single-phase three-wire 60-Hz circuit serves lighting, heating, and motor loads, as shown in Fig. 9.38a. Lighting and heating loads are essentially pure resistance and, hence, unity power factor (pf), whereas motor loads have lagging pf. We wish to design a balanced configuration for the network and determine its economic
viability using the following procedure.
a. Compute the phase and neutral currents, as well as the complex power and pf for each source.
b. Now move the heating load (panel H) to phase b, as shown in Fig. 9.38b. This is called “balancing” the load. Repeat the analysis of (a).
c. Assume that the phase and neutral conductor resistances are each 0.05 Ω and have negligible effect on the results of (a). Evaluate the system line losses for (a) and (b). If the loads in question operate 24 hours per day and 365 days per year, at $0.08/kWh, how much energy (and money) is saved by operating in the balanced mode?
