For devices driven by variable-frequency motors, are there any special requirements for the selection of couplings?
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There are eight variable-frequency pumps here, and the couplings are particularly heavy – is there any reason for that?
There are no special requirements; it depends on the type of pump, mainly on how the load and torque change with speed – whether it is a constant power or constant torque system Constant torque is a bit more troublesome, as the coupling becomes quite heavy
It depends on what kind of pump it is, as well as the level of coupling configuration; it has nothing to do with whether the drive is variable frequency or not.
The coupling of the centrifugal pump has nothing to do with variable frequency drive; it is likely that the cheapest cast-iron elastic sleeve pin coupling was used, which is why its size is so large
I didn’t say it all; it’s a diaphragm coupling with an intermediate shaft
Can it be determined on-site whether it is constant power or constant torque?
Diaphragm couplings are considered a high-end option, and they have nothing to do with variable frequency drives.
Constant power above the power frequency (50Hz), constant torque below the power frequency.
Oh, it’s a centrifugal pump. The thick coupling is due to the design choices made by the coupling manufacturer; standards are followed in such cases, and it’s common to use larger couplings instead of smaller ones. There may be other considerations as well, but there’s nothing to question