Ramp Up Time

[macardoso]

I agree with @Ulma Doctor a VFD seems like the way to go and you get many other features to boot. I haven't used a 1-phase-1phase VFD but assume similarity to 1-phase-3-phase unit.
Aaron

Single phase VFDs do exist but cannot be used with 99% of single phase motors. There are special single phase motors without the centrifugal switch for this application.

VFDs, more or less, dictate the use of a 3 phase motor. They can usually be found quite cheaply.

 

[AGCB97]

I learned something new. Not that I would ever go that way anyway.
Thanks @macardoso

 

[Happycamper]

I learned something new. Not that I would ever go that way anyway.
Thanks @macardoso

I’ve been looking at the single phase to single phase vfd. The wiring schematic shows that they can be used with or without the capacitors. Anyone have personal knowledge of these?

 

[Ulma Doctor]

Here's one that looks interesting: Only 50 bucks

Single-phase Motor Soft Starter Module 220V Controller 2KW4KW6KW8KW Starting Fan | eBay

Single-phase 220V soft start module use range (220V + 0V = single-phase 220V, AC). 220V. (50Hz, 60Hz). (220V + 220V = two-phase 380V--400V, AC). Single phase motor compared to starter module. our soft start is universal for the motor, regardless of whether the motor has a capacitor or not.

www.ebay.com

the problem with the less expensive starter is there is no provision for capacitance
there will be need to compensate somehow if the intended motor has start or run capacitors

 

[RJSakowski]

I’ve been looking at the single phase to single phase vfd. The wiring schematic shows that they can be used with or without the capacitors. Anyone have personal knowledge of these?

From what I have read, the problem seems to be the centrifugal switch in the starter circuit. When you slow the motor down,with the vfd, the start circuit is energized. The start circuit is only intended to be energized for a dew seconds. Anything longer can overheat the winding and destroy the motor. There are some workarounds though.

In theory a vfd should be able to work with a single phase motor, once running. The motor rpm is proportional to the energizing frequency. On fact, many motors can run on either 50 or 60 hz. A 1720 rpm motor at 60 hz will run at at 1430 rpm on 50 hz. Presumably, running at in 40 hz will drop the rpm even further.

Something else that should be considered if looking for a vfd for a single phase motor is that most of those that I have seen are intended to be used on fan motors which will have a smaller load on startup than a drive motor for a lathe or mill.

 

[markba633csi]

I have found that making the start capacitor a smaller value will slow the startup somewhat. Obviously, you can only reduce it so far- maybe by 40% of the full value. So for example on a 200 uF cap you could try around 125. This might not be a viable option on something with a high startup load like a compressor, or a permanent split cap motor that needs the cap while running
-Mark