Can domestic frequency converters achieve a 20% energy savings out of nowhere?
Thread Content
A manufacturer came to promote an energy-saving device (servo energy saver); it’s similar to an inverter, but it doesn’t have PID closed-loop control and operates at a fixed frequency. After using the electricity meter, energy consumption is reduced by 20%-30% (the same holds true for the same frequency and rotational speed); I still can’t understand the principle behind this. After the equipment was put into use, higher levels of harmonics were detected at the transformer’s output, with even-order harmonics present as well. The noise generated by the transformer increased significantly (the transformer has a capacity of 2500 KVA, while the equipment itself has only 30 KW). An imbalance in the three-phase current was observed at the input side of this energy-saving device, and the reactive power value was negative
Such manufacturers might originally come from acrobatic families, or they may have learned from David * Copperfield. Frequency conversion technology can save energy, but it causes the reactive power to become negative (in other words, a certain amount of power must be consumed in order to bring the reactive power to zero) ； In other words, it means that without consuming a certain amount of power, this motor is able to generate electricity out of thin air); the technology is so advanced that we can’t understand it.
Energy conservation means reducing the operating power; a decrease in power leads to a reduction in the output electromagnetic torque, which in turn results in a lower output power on the shaft. Does the motor current also decrease?
Variable-frequency energy-saving technology is generally used in pumps and fans. Taking a traditional fan as an example, the speed of the motor remains constant; any adjustments are made through the damper, and most of the losses occur at the damper； With variable-frequency control, the speed can be adjusted, and at the same time the current can be reduced, thereby decreasing the active power input. Yet the volume of air generated remains the same, which achieves energy-saving effects.
Variable frequency drives are used to control AC motors in order to achieve energy savings； Servo drives are used to control servo motors. The targets and principles of energy-saving services for servo drives are completely different from those of frequency converters, and the two should not be confused.
What was said on the 4th floor is correct – frequency converters generally save energy only in applications with load profiles that follow a quadratic curve, such as fans and water pumps. It is almost impossible to save energy when torque power remains constant (law of conservation of energy).
It’s a lie; I guess there are more capacitors inside, which increases the reactive power: lol
For mixers and motors that originally used hydraulic coupling for speed control, switching to variable-frequency speed control can still achieve a certain degree of energy savings by reducing losses in the mechanical transmission components.
In my opinion, if you think energy savings are possible, it means that your previous equipment was wasting energy: devices such as fans or pumps may not have required such high pressure or flow rates in terms of the system or process requirements; by using variable frequency drives, the appropriate pressure, flow rate, or lift can be achieved, which leads to energy savings. If variable frequency drives are used without making any adjustments to the parameters, then no energy savings will occur
The law of conservation of energy has not been proven to be wrong, at least for now