Abstract
Demand and duty factors were measured for selected equipment [air compressors, electric furnaces, injection-molding machines, a welder, a granulator (plastics grinder), a sheet metal press and brake, a lathe, a process chiller, and cooling tower pumps and fans] in two industrial plants. Demand factors for heavily loaded air compressors were found to be near 100 %, for lightly loaded centrifugal equipment (lathe, sheet metal shear and brake, and granulator) near 10 %, and for injection-molding machines near 50 %. The measured demand factors differ from those often estimated during energy surveys. Duty factors for some equipment were found to exceed 100 %, showing that some loads were on for longer periods than that indicated by plant personnel. Comparing a detailed summary of equipment rated loads to annual utility bills, when measurements are not available, can prevent over-estimation of the demand and duty factors for a plant. Raw unadjusted estimates of demand factors of 60 % or higher are often made, yet comparisons of rated loads to utility bills show that some equipment demand factors may be 50 % or less. This project tested a simple beacon alerting system, which used a blue strobe light to alert plant personnel when a preset demand limit had been reached. Tests of load shedding verified that the estimated demand savings of 50 kVA were realized (out of a total demand of almost 1200 kVA) when lighting and air conditioning loads were turned off.
Dooley, Edward Scott (2001). A Study of Industrial Equipment Energy Use and Demand Control. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2001 -THESIS -D67.