Perfect Harmony SNG5100 Series High-Voltage Variable Frequency Speed Regulation System

SN6100 Internal Feedback Chopper Wave Speed Regulating Device
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Principle of Energy Saving for Water Pumps (Fans): Lift and Flow H-Q Character Diagram
During the operation of water pumps, the flux shall be frequently adjusted. The traditional way for flux adjustment is to change the opening of the valve. If the opening of the valve is smaller, the efficiency of valve operation will be reduced. As shown in the diagram, S1 is the lift-flux characteristics of rated operating water pump, R1 is the resistance characteristics in maximum valve opening, M1 is the rated operating point whose corresponding lift is H1 and the flux is Q1. Th e co nsumed power of motor is in direct proportion with the product of H and Q: P1=K H1 Q1; wherein, K is the p ropor tiona lity facto r. If the flux is reduced to Q2 by turning down the valve, the resistance characteristics of the pipe network is R2 and the operating point of the water pump is M3. At that time, the lift will be in creased an d the cons umed power of t he motor will be reduced slightly: P2=K H3 Q2; wherein, K is the proportionality factor. If the rotating speed is lowered, the lift-flux characteristics will be changed into S2, the resistance characteristics of pipe network is still R1 and the operating point of water pump is M2. At that time, the lift can be lowered more and the consumed power of motor can be greatly reduced: P3=K H2 Q2; wherein, K is the proportionality factor. Clearly from the diagram on the right, under the same flow Q2, t he lift H2 when lowering the rotating speed is much smaller than the lift H3 when turning down the valve, so the con sumed power of motor can be greatly reduced. This is the simple principle on energy saving of water pump by speed regulation.
Relationship Between Rotating Speed and Shaft Power of Fans (Water Pumps)
(Based on the Input Power P Base of the Motor in 100% Rotating Speed)
Rotating Speed 100% Nn 90% Nn 80% Nn 70% Nn 60% Nn
Motor Power 100%P Base 72%P Base 51%P Base 34%P Base 21%P Base
Note:
1. The Table above takes the full-opening baffle plate of fan and no change on other states of load when changing the rotating speed of motor as the condition;
2. When the number of revolutions is changed, the self-efficiency of fan shall not be reckoned.
Energy Saving Analysis
The energy saving amount of water pumps or fans depends on the peakchange of the operating condition. According t o the operating report on measurement of speed regulating device manufactured by our company for years in actual operation on site as well as self-measurement conducted by customers, the average minimum energy-saving rate is more than 30-50%, which is an energy-saving speed regulating device with less investment and quick returns.
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