12-09-2013, 12:39 PM
Effect of Voltage and Load Variations on Efficiencies of a Motor-Pump System
Voltage and Load Variations.doc (Size: 564.5 KB / Downloads: 26)
Abstract
Centrifugal pumps are the most widely used ac- motor-driven pump systems mainly for water pumping applica- tions. Due to increasing and varying load demand, voltage varia- tion and unbalance is a reality and has to be dealt with carefully. Studies on motor-driven systems under conditions of voltage un- balance have either neglected or maintained constant magnitude of the rotational loss component and focused only on the motor per- formance while system side performances have not been discussed generally. This paper presents the experimental results of a three- phase induction motor-pump system subjected to voltage and load variations with a view to justify that knowledge of voltage and load variations are very much essential for better result analysis.
Motor Side Analysis
Under varying voltage and load conditions, core loss and/or windage and friction losses are generally neglected, the reason being ease of understanding and result analysis [6], [8], [10], [12], [15], [18]. Accurate estimation of losses is very important
Pump Side Analysis
The performance of a pump can be graphically expressed by plotting curves of head (H) versus flow rate (Q), as shown in Fig. 2. The pump curve is interpreted as what a pump can offer at a particular speed, and is a plot of pump head versus flow rate. The system curve is interpreted as what is desired by the system, and is a plot of total head versus flow rate.
CONCLUSION
The focus of this paper is to present the performance vari- ations for a three-phase induction motor-pump system being subjected to varying voltage and load conditions. The voltage variations are in the form of balanced and unbalanced, over- and undervoltages. The load variations are in the form of change in the throttle opening placed on the delivery side. The variations