Silt Pumping Plant Rehabilitation Preliminary Design

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Preliminary Design Memorandum Silt Pumping Plant Rehabilitation • Excellent for maintaining distribution system power factor Disadvantages: • Complex equipment to maintain requiring specialized expertise • Significant decrease in pump efficiency at slower speeds because operating point on pump curve shifts dramatically to the left and moves away from BEP. This disadvantage can be mitigated by careful selection of the correct combination of pumps to avoid speeds less than 90%. • VFDs produce heat while operating and electronic components are susceptible to failure when exposed to high ambient temperatures. This may dictate the installation of additional HVAC equipment.. Equipment tends to be larger which could impact available space in the facility. Fixed-speed Pumps Advantages: • Electrical equipment is simpler to maintain. • Fixed-speed pumps are reliable. Disadvantages: • Not able to exactly match irrigation demand resulting in excess water being pumped to the pump canal. Only a '/4 of the excess water is eventually sold. • Soft starters will be required to utilize the local feeder transmission line for motors 200 horsepower and greater. The medium and large pumps will therefore require soft starters. • With the selection of induction motors,power factor charges could be levied by the utility. Compensation for the power factor issues can be addressed using power factor correction capacitors with an integrated controller. • Equipment is less complex than the VFD however specialized expertise may still be required. • Electronic components are susceptible to failure when exposed to high ambient temperatures. This may dictate the installation of additional HVAC equipment. Recommendation: The energy savings alone offered by the VFDs do not appear to be large enough to make the VFDs financially attractive. The electrical issues need to be evaluated to determine if VFDs have additional benefit. Sufficient information to 22 FOR OFFICIAL USE ONLY