Suppliers of energy feedback devices for frequency converters remind you that energy saving of frequency converters is mainly reflected in the application of fans and water pumps. In order to ensure production reliability, various production machinery are designed with a certain margin of power drive. When the motor cannot operate at full load, in addition to meeting the power drive requirements, the excess torque increases the active power consumption, resulting in the waste of electrical energy. The traditional speed regulation method for equipment such as fans and pumps is to adjust the air and water supply volume by adjusting the opening of the inlet or outlet baffles and valves. This method has a high input power and consumes a large amount of energy during the blocking process of the baffles and valves. When using variable frequency speed regulation, if the flow rate requirement is reduced, it can be met by reducing the pump or fan speed.
According to fluid mechanics, P (power)=Q (flow rate) × H (pressure), the flow rate Q is proportional to the power of the rotational speed N, the pressure H is proportional to the square of the rotational speed N, and the power P is proportional to the cube of the rotational speed N. If the efficiency of the water pump is constant, when the required flow rate decreases, the rotational speed N can decrease proportionally, and at this time, the shaft output power P decreases in a cubic relationship. The power consumption of the water pump motor is approximately proportional to the rotational speed. When the required flow rate Q decreases, the output frequency of the Delta inverter can be adjusted to proportionally reduce the motor speed n. At this point, the power P of the electric motor will decrease significantly according to a cubic relationship, saving 40% to 50% of energy compared to adjusting baffles and valves, thus achieving the goal of energy conservation.
For example, when designing and installing water pumps, the maximum usage is considered and a certain margin is left. However, in practical work applications, it is difficult to achieve the maximum usage, which leads to the phenomenon of "a big horse pulling a small car". Traditional methods of regulating flow are achieved by controlling the opening of valves. As a result, the operating efficiency of the water pump is only 30% -60%, which not only incurs high costs but also wastes valuable electrical energy.
Variable frequency drive regulation technology:
Due to the fact that water pump loads belong to square torque loads, their flow rate (Q), head (H), power (P), and motor speed (n) are related as follows
Q1/Q0=n1/n0 H1/H0=(n1/n2)^2 P1/P0=(n1/n2)^3
Q0, H0, P0, n0 are the quantities under rated operating conditions.
Q1, H1, P1, and n1 are the quantities in actual operating conditions.
Therefore, by changing its speed to control its flow rate to achieve practical goals, frequency converter technology changes the motor speed by changing the frequency of the power supply, and the power changes proportionally with the third power of the speed, saving energy very significantly. Moreover, it has the characteristics of simple operation, convenient maintenance, stable operation, and wide speed range, making it widely used in the field of water pumps.