A small machine shop, with 30 hp of connectedload,

Chapter , Problem 2-5

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A small machine shop, with 30 hp of connectedload, purchases electricity at the following monthlyrates (assume any demand charge is included in thisschedule) per hp of connected load:First 50 kWh at 12.6?cperkWhNext 50 kWh at 10.6?cperkWhNext 150 kWh at 6.0?cperkWhOver 250 kWh at 5.7?cperkWhThe shop uses 2800 kWh per month.(a)Calculate the monthly bill for this shop.What are the marginal and average costs perkilowatt-hour?(b)Suppose Jennifer, the proprietor of the shop,has the chance to secure additional business thatwill require her to operate her existing equip- ment more hours per day. This will use an extra1200 kWh per month. What is the lowest figurethat she might reasonably consider to be thecost of this additional energy? What is this perkilowatt- hour?(c)Jennifer contemplates installing certain newmachines that will reduce the labor time requiredon certain operations. These will increase theconnectedload by 10 hp, but since they will oper-ate only on certain special jobs, will add only100 kWh per month. In a study to determine theeconomy of installing these new machines, whatshould be consideredas the cost of this energy?What is this per kilowatt-hour?