Author Topic: PUMP SPEED  (Read 864 times)

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Burnrate

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PUMP SPEED
« on: January 27, 2005, 03:14:10 PM »
I have a 120volt 360watt 3.2amp 3600gph submersible pump that I would like to change the output on. I know that I can use valves to dial the flow down. Is there a better way to slow the pump. Less voltage to the pump? What would I need to make it work.

Eric
« Last Edit: January 27, 2005, 03:14:10 PM by (unknown) »

Opera House

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Re: PUMP SPEED
« Reply #1 on: January 27, 2005, 10:17:13 AM »
Reducing the voltage on induction motors can reduce the speed slightly by increasing the rotor slip.  This causes excessive motor heating and trouble starting.  In indusrial pumps, you can often buy different impellers to change the head and flow rate.  If you have the ability, you can cut down the present impeller and try to balance it after.  That leaves you with the option of bypassing flow or going with another pump.
« Last Edit: January 27, 2005, 10:17:13 AM by (unknown) »

wooferhound

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Re: PUMP SPEED
« Reply #2 on: January 27, 2005, 11:51:11 AM »
I would suggest a variable transformer, also known as a Variac.


 I use them on fans around the house here . . .

« Last Edit: January 27, 2005, 11:51:11 AM by (unknown) »

Drives

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Re: PUMP SPEED
« Reply #3 on: January 27, 2005, 06:05:47 PM »
Change the motor to a 1/2 hp, 208-230 vac, 3 phase motor, and purchase a 208-230vac variable frequency drive.  You will need your household 208-240vac power to power the VFD.  You can feed most small VFD's with single phase in to get 3 phase out.  If the drive does not specifically say it is rated for single phase input, then you will need to purchase a 1 HP, 3 phase rated VFD to handle the higher single phase current input.

You would be surpried by how cheap the motor, and VFD are on ebay.  Just be sure the motor is the same frame size, and RPM rating.

The way to efficently change the RPM of an induction motor is to change the frequency of the power feeding to it.  
« Last Edit: January 27, 2005, 06:05:47 PM by (unknown) »

drdongle

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Re: PUMP SPEED
« Reply #4 on: January 28, 2005, 06:56:15 AM »
Bad idea, as stated by opera house this will cause problems, induction motors are not designed to be controlled by variable voltage like a DC, series or shunt wound motors. With the pump in a bore hole when it goes bad it's a bear to fix. A VF motor drive would be a better solution but admittedly a very expensive one.

The best solution would be to replace the current pump with a DC unit ( like a solar jack) and the use the appropriate voltage for the amount of water you need.
« Last Edit: January 28, 2005, 06:56:15 AM by (unknown) »