Opening degree of variable-frequency pump
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Is a variable-frequency pump still more energy-efficient than a fixed-frequency pump even when its operation level is at 100%?
The principle of energy savings with variable-frequency pumps is that they can operate at different frequencies depending on the requirements, thereby avoiding the situation where a powerful pump is used for tasks that require a less powerful pump. If a variable-frequency pump operates at a fixed frequency, it will not be more energy-efficient than a pump that operates at the standard frequency.
When the frequency is increased to 80 or above, it becomes the same as the power frequency.
The energy savings offered by variable-frequency pumps come from using frequency changes to meet varying flow requirements; if a variable-frequency pump operates at 100% capacity for an extended period, it is advisable to switch to a conventional frequency pump for greater reliability
During this period, the unit has been operating at full capacity; in addition, some external gases have entered the unit, which has resulted in a high load on the stabilization systems. The frequency of operation of the liquefied gas pump is around 98%
Even when it is set to 100%, the speed of the motor on-site is still lower than that at the power frequency – isn’t this a waste of energy?
High load and low speed are not conducive to motor cooling; in fact, it’s not good! Moreover, the low-load operation of variable-frequency motors is generally not less than 20%!
This post was last edited by longziyun on 2018-9-10 at 23:20. Variable frequency drives are most suitable for applications where energy savings are important; they become useful in situations with significant variations. If it’s just the motor that’s larger and the operating conditions remain unchanged, then replacing it with a smaller motor would surely result in energy savings. As for the situation where everything is already running at over 90% capacity, there’s no point in trying to save electricity any more; in fact, the high load may even cause shutdowns, which would be counterproductive.
Variable frequency is used to facilitate flow regulation and reduce energy consumption. The frequency conversion should not be too high. When the frequency conversion is too high and there are fluctuations in the pump, the current also fluctuates, which can easily lead to failures in the frequency converter.
No energy savings: originally we had two reciprocating compressors, one with variable frequency and one with fixed frequency. As the workload increased, the variable frequency compressor was operated at 90%, but in the end it turned out that the compressor with fixed frequency used less energy than the one operating at 90% frequency.