Author Topic: 240v Single Phase VFD (diagram wanted please)  (Read 653 times)

0 Members and 1 Guest are viewing this topic.

Offline SvenIronhandTopic starter

  • Newbie
  • Posts: 2
  • Country: za
240v Single Phase VFD (diagram wanted please)
« on: January 29, 2020, 11:26:23 am »
So I have a problem. I need to build a VFD to run a pool pump motor. It's a 1.1kw/1.5HP motor (single phase). I have lots of all sorts of components at home. Also I'm in South Africa where we have 240v supply.
So the question is does anyone know of a place where I can find a circuit diagram for a DIY 1.5kW/2HP VFD. I've looked but haven't really found anything. I don't have much money so I need a free or very cheap less than AU$15 diagram.
 

Offline GerryR

  • Frequent Contributor
  • **
  • Posts: 256
  • Country: us
Re: 240v Single Phase VFD (diagram wanted please)
« Reply #1 on: January 29, 2020, 11:46:04 pm »
Single phase motors are synchronous; VFD's are used to drive 3-phase motors.  VFD's can run off of single phase power (input), but they output 3-phase to the motor.  So, you need to get a VFD and a 3-Phase motor.
Still learning; good judgment comes from experience, which comes from bad judgment!!
 

Offline Ground_Loop

  • Frequent Contributor
  • **
  • Posts: 674
  • Country: us
Re: 240v Single Phase VFD (diagram wanted please)
« Reply #2 on: January 30, 2020, 02:44:22 am »
Many problems here. First off a standard single phase induction motor is not synchronous. It develops torque through slip just like a three phase motor. However, most single phase induction motors have switched start capacitors and possibly a run capacitor as well to start and maintain a rotating field.  These need to be dealt with.  I have never seen a VFD that was compatible with a single phase motor and I have literally installed about 10000 of them. In fact I have three operating in my home shop and four spares on my shelf.

Single phase sourcing VFDs is common practice, but attempting to drive single phase motors with most VFDs will cause a phase imbalance fault.

In addition if you are trying to control flow in a centrifugal pump with a vfd it will be difficult due to the flow characteristics of centrifugal pumps. If you are trying to save energy cost, a simple throttle valve at the outlet will work. The pump draws less power as it does less work on the fluid.  Avoid throttling on the inlet because it can cause cavitation and pump inlet erosion .

I don’t see a VFD as a viable option in your situation.
« Last Edit: January 30, 2020, 03:30:14 pm by Ground_Loop »
There's no point getting old if you don't have stories.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf