These are all engineering issues that should be addressed. It really seems like yet another case of the controls guy being tasked with compensating for someone's poor engineering.
And as normal, they don't want to spend any money doing it!
These are all engineering issues that should be addressed. It really seems like yet another case of the controls guy being tasked with compensating for someone's poor engineering.
So the good running pump will automatically have many usage hours more that the motor and pump that is being rebuilt. If the good pump has at least as much run time as it will take to get the other pump rebuilt, then alternating the two units makes a lot of sense. That way the current pump will fail first with at least enough assumed time left on the other pump to get the failed unit rebuilt and reinstalled.This is why my immediate need is to slow down the pump. I need a vfd to do that. The idea of using contactors on the outlet of the vfd is a complete secondary. The contactors are already in the panel and will be coming out. Instead of benching them, I though I could put them to use in this way.
So the good running pump will automatically have many usage hours more that the motor and pump that is being rebuilt. If the good pump has at least as much run time as it will take to get the other pump rebuilt, then alternating the two units makes a lot of sense. That way the current pump will fail first with at least enough assumed time left on the other pump to get the failed unit rebuilt and reinstalled.
I'm interested in knowing more about this nanofilter you are using. I'm facing the need to place an isolated cooling loop between a cooling tower and a process heat exchanger that requires super clean water but cannot use deionized water.
Why modify the already packaged system at all? Who knows what other problems you'll introduce by running the system at reduced pressure/flow.
What about adding a surge tank between the utility and the system? 500 gallons is not that large a tank and would provide 3 minutes of volume. Can the system be cycled in this manner?
Again, suggest you look into ABB's Pump/Fan Macro. You get, with the timed rotation option, equal running hours on each pump with continuously variable control with a single VFD.