Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Permanent Magnet Pump Speed Control

  1. Jan 5, 2004 #1

    I have a submerged magnetic water pump that is pushing too much water at 8500L/hr. I know that the propeller rpm depends on the frequency of the AC supply but how can I build a simple circuit to reduce the frequency?

    Thanks :smile:
  2. jcsd
  3. Jan 5, 2004 #2

    Could you brief me about ur device so that I can try to figure out some way of reducing the frequency.? How does your pump work?

  4. Jan 5, 2004 #3
    Its has a magnetic rotor that will spin when switched on, this rotor is connected to a propeller that pushes the water. I need something that can reduce the frequency of the AC supply so that the propeller will spin at a lower rpm. The best solution would be something like a rheostat where I can adjust the speed with a turn of a knob.
  5. Jan 5, 2004 #4
    Do you know the current rating of the motor?

    I found this schematic that you might be able to use.

    http://www.electronics.50g.com/cacspeed.htm [Broken]
    Last edited by a moderator: May 1, 2017
  6. Jan 5, 2004 #5
    Its a small pump, rated at 17watts/230V/50Hz.

    I would need something for 230V

  7. Jan 5, 2004 #6
    Sorry, I shouldn't assume 110/120 V.

    Not much current draw at all. That control circuit is rated at 10 A at 120V. The maximum power it can handle is 1200W. Since your motor is rated at 17 watts, it would have no problem handling the power requirements of your pump at 230V.

    A google search for "AC motor speed control" will yield lots of hits if you want to look for other circuit designs.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook