Convert the shaft ouput from HP to kW
Shaft output = 75HP = 55.93kW
1st: Finding for the power consumption based
on 55.93kW output
Power consumption (Old) = 55.93kW / .910 = 61.46kW
Power consumption (New) = 55.93kW / .954 = 58.63kW
2nd: Total power used in kWh:
Power Used = Power consumption * load factor * Hours:
Power (Old) = 61.46kW * .75 * 4368 = 201343 kWh
Power (New) = 58.63kW * .75 * 4368 = 192072 kWh
Energy saved = 201343 kWh - 192072 kWh = 9,271 kWh
3rd: Calculating for the price:
Price = kW-Hr * $/kWh
Price (Old) = 201343kWh * $0.08/kWh = $16107.44
Price (New) = 192072 kWh * $0.08/kWh = $15365.76
Cost saved = $16107.44 - $15365.76 = $741.68/yr
4th: Setting up the cost equation:
Cost over time, F(t) = Motor_Cost + (Price * Number of
Years, t)
Cost (Old) = 5449 + 16107.44*t
Cost (New) = 5520 + 15365.76*t
Equate the two to find for t when they cost equally:
5449 + 16107.44*t = 5520 + 15365.76*t
16107.44*t = 15365.76*t +71
16107.44*t - 15365.76*t = 71
741.68*t = 71
t = 71 / 741.68 = .095 years = 35 days
So the payback period is after 35 days.
