Please Help - 3 water pumps running in parallel

[Tony1mail]

Hey Guys
I am based in China and have 3 identical 60 meter 220v 1500 w water pumps supplying water up a hill of height about 120 meters and distance about 260 meters. They are currently connected in parallel but the problem is that they are all running at different speeds hence the water is not being supplied as one pump is just running too slow. The rise in height is not the same for each pump, could this be the problem? Any suggestions how these can all be balanced to work at the same speed. Is it easiest just to run separate cables to each putting them on an independent feed but operated from just the 1 switch?
Many thanks.
Tony

 

[Darkwood]

Where is the motor protection if the're all in parallel then, their are numerous ways to give equal flow but not really enough info to suggest any particular solutions but if you run seperate supplies to the 3 motors and run these motors off an inverter then have the inverter been controlled by local flow rate sensors then the 3 inverters can be linked to one start stop system and the motors will self adjust to give equal flow once set up right. Its not a cheap solution but it gives motor control and protection in one. Their is a few other ways but what are the limitations, and is the pipe one continuous run or is the water pumped into sump wells in stages?

 

[Tony1mail]

Thanks darkwood for your reply.

Yes there are holding tanks at each stage. We will change the set up using flow rate rate sensors and I will keep you posted.

Many thanks
Tony

 

[Darkwood]

Thanks darkwood for your reply.

Yes there are holding tanks at each stage. We will change the set up using flow rate rate sensors and I will keep you posted.

Many thanks
Tony

A cheaper solution if you have holding tanks is to use float switches to bring on the motors on and put progressively more powerful pumps on as you rise so the tanks dont breach an high level sensor unless their is a fault with the motor, its not the best solution but its a cheaper alternative, this way you can have a control board at each pump station and use the existing cable as a permanent supply to the 3 control boards.
The high level sensor should sound an alarm in case the motor fails or the pump level float switch fails and the holding tank fills too high, it you link all 3 control stations you could use the high level as an e-stop circuit shutting all 3 down.

 

[Tony1mail]

Thanks again. Yep float switches sounds like a simpler idea. Is parallel the best way to run them ?

Cheers
Tony

 

[Darkwood]

Thanks again. Yep float switches sounds like a simpler idea. Is parallel the best way to run them ?

Cheers
Tony

Turn the loop cable running the motors into a supply cable to each motor control station then transform down to a safe voltage to control the contactor via the float switch in each control, at the first motor run the power through a contactor which is only dropped out if any of the high level floats are triggered thus cutting all power.
the motors should be progressively more powerful so the water well cannot be overfilled by a lower motor before it can be pumped back out.
Note you are increasing 2 motors to larger sizes so make sure your supply and cable are still big enough and the above is an old crude methed but cheapest for your application you need to adapt it to suit your situation as im only getting limited info so its a guide rathe than a solution.