Considerations for an economic evaluation of AC versus DC technology for paper machine drives

Many of the considerations for comparing AC and DC drive systems for paper machines are discussed. These include the system purchase price, spare parts, motor cooling, cable cost, power factor, harmonics, efficiency, motor and controller maintenance, and space requirements. The net present value (NPV) technique is presented for making an economic evaluation between the two technologies. The NPV method of investment evaluation accounts for the time value of money by discounting all cash flows to present value using the required rate of return