Driven by an inverter; please offer some advice, experts
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The Hollyland MACSV5.25B DCS system is equipped with 3 ABB frequency converters connected to 3 water pumps. The outlets of these 3 pumps are all connected to a main pipe; at the outlet of this main pipe there is one pressure transmitter and one flow transmitter, with one unit in use and two as spares. The design intended to use pressure or flow values to automatically control the frequency output of the frequency converters. However, during actual testing on site, it was found that even when one pump operated at full capacity, the flow rate was not sufficient for practical use – it was necessary to start both pumps simultaneously to meet the requirements. Now the question is: how can we achieve automatic control of the frequency output of these 2 frequency converters? Should the frequency output signal be divided by 2? There is also the issue of distributing the signals to the frequency converters. I’m thinking of using the start signal from the frequency converter to determine which one should receive the frequency signal – that is, when a start signal is received for a particular frequency converter, that converter is supplied with the frequency signal. Is this a viable approach? I hope the experts here can give some advice; thanks in advance.
If the signal is divided by 2, another issue that arises is how to ensure that a water pump operates at full capacity
I think the poster should follow this procedure for low-load control: first, one pump must operate at full load, and that pump should be controlled manually, while the controller selects an inverter with a lower load capacity. Of course, it refers to the operating pump; the standby pump is not taken into consideration in the selection. The automatic timer controller then performs output limiting to ensure that the outputs of the two frequency converters do not both reach their maximum value at the same time.
I haven’t used the Shili system, so I don’t understand it. However, the Yokogawa CS3000 has a cascade signal distribution function (FOUT) that allows for even frequency distribution across two inverters; I believe you use this feature as well. Actually, the original poster could change their approach: since one unit isn’t sufficient when operating at full capacity, that unit can be used at the standard frequency without any need for frequency control; it’s sufficient to control the frequency of the other unit in order to maintain stable flow and pressure
Is it possible for one unit to operate at the mains frequency without variable frequency control, while the other unit is controlled via variable frequency? Of course, the frequency cannot be too low, as that would affect the motor~~
Thank you. I also plan to have one water pump operated manually at a fixed frequency of 40Hz, while the other pump will be under automatic control, with a frequency range of 20Hz to 40Hz, which should meet the operational requirements.
Thank you. I also plan to have one water pump operated manually at a fixed frequency of 40Hz, while the other pump will be under automatic control, with a frequency range of 20Hz to 40Hz, which should meet the operational requirements.
Thank you. I also plan to have one water pump operated manually at a fixed frequency of 40Hz, while the other pump will be under automatic control, with a frequency range of 20Hz to 40Hz, which should meet the operational requirements.
The operating frequency at normal conditions should be 50Hz, right? If 40Hz is set, will the water pump’s output be less than 2/3?
One operates at a fixed frequency, while the other operates with frequency modulation
Yes, that’s better. Only one water pump is operating at variable frequency, which simplifies the issue.