Hi guys , I have a 3 phase 415v 5.5kw compressor wired Dela that I wish to run on 240v single phase .From my understanding I have to change to motor wiring from Delta to WYE ? and do I need any other wiring apart from 240 in (R T and Earth ) and then run wires from U V W and earth to the motor? Please see my colour coded diagram to make sure I have it correct .In Australia Brown is Active ,Blue is neutral

 

Hi,
first of all, open the motor junction box and found a connection diagram. Or, check if motor winding is connected in WYE . If so, reconnect it to Delta. If winding is connected in Delta , you can't power up it from a 240V source.
Take account, current from the mains will exceed 25 Amps or so. Check also, if your frequency converter can be powered from a single phase

 

Hi,
first of all, open the motor junction box and found a connection diagram. Or, check if motor winding is connected in WYE . If so, reconnect it to Delta. If winding is connected in Delta , you can't power up it from a 240V source.
Take account, current from the mains will exceed 25 Amps or so. Check also, if your frequency converter can be powered from a single phase

This is Delta ? so I don't need to change it to WYE ? and yes it is a 7.5kw single to 3 phase vfd

 

 

This is Delta ? so I don't need to change it to WYE ?

It appears that way, but there should be a data plate on the motor that could provide confirmation.

and yes it is a 7.5kw single to 3 phase vfd

Are you sure about that? 7.5kW/10HP is larger than what is typically offered for single-to-3ph VFDs. Usually those only go up to around 3-5HP and if you need more HP in a single-to-3ph application you have to buy a much larger 3ph VFD, disable the input phase loss detection, and de-rate the VFD. what is manufacturer and model # of the VFD?

Take account, current from the mains will exceed 25 Amps or so.

That is technically true, it will exceed 25A. But I think you may be considering 3ph mains load when the application is single phase mains. Australia is 220-240V and 7500W/220V = 34A. To provide 150% capacity (usually allowed by VFD for up to 60s and probably necessary for compressor application) I would suggest sizing mains wiring and breaker at 50A.

 

It appears that way, but there should be a data plate on the motor that could provide confirmation.

Are you sure about that? 7.5kW/10HP is larger than what is typically offered for single-to-3ph VFDs. Usually those only go up to around 3-5HP and if you need more HP in a single-to-3ph application you have to buy a much larger 3ph VFD, disable the input phase loss detection, and de-rate the VFD. what is manufacturer and model # of the VFD?


That is technically true, it will exceed 25A. But I think you may be considering 3ph mains load when the application is single phase mains. Australia is 220-240V and 7500W/220V = 34A. To provide 150% capacity (usually allowed by VFD for up to 60s and probably necessary for compressor application) I would suggest sizing mains wiring and breaker at 50A.

The VFD IS A VEVOR A2-8075 7.5kw https://www.vevor.com.au/variable-f...sd-converter-single-to-3-phase-p_010337363762

 

The motor is 5.5kw so I purchaced what I thought would be a bit of an over kill being 7.5 kw

 

The motor is 5.5kw so I purchaced what I thought would be a bit of an over kill being 7.5 kw

Good call. Compressor applications are hard on VFDs. I did not catch the 5.5kW motor part. In that case I would size mains wiring and breaker for 40A.

The VFD IS A VEVOR A2-8075 7.5kw https://www.vevor.com.au/variable-f...sd-converter-single-to-3-phase-p_010337363762

Well, that's cool. Let us know how it turns out. If that VFD isn't a turd then I will bookmark it for future use.

 

On the photo motor is connected in Delta. So, you can't supply that motor from 240V . If reconnected to WYE, it should be powered from 720V. Two alternatives available for the motor- 415V or 720V

 

On the photo motor is connected in Delta. So, you can't supply that motor from 240V . If reconnected to WYE, it should be powered from 720V. Two alternatives available for the motor- 415V or 720V

Why not ? the motor can be configured to either star or delta (see pic from the motor) and the VFD takes in 240v single phase and outputs 3 phase

 

On the photo motor is connected in Delta. So, you can't supply that motor from 240V . If reconnected to WYE, it should be powered from 720V. Two alternatives available for the motor- 415V or 720V

Is 720V a valid mains nominal anywhere in the world? I've never heard of it. It seems much more likely 240D/415Y (or 220D/380Y) and already connected in delta, so already set up to run on 240V. But still would like to see the motor data plate for confirmation.

 

But still would like to see the motor data plate for confirmation.

I took these yesterday hard to read need to clean it up; some ...what's it telling you?

 

The plate does not appear to show the details for the Delta connection?
The plate in #10 does show the Star/Delta options though.
Generally VFD's do not go that high a HP for 1ph supply versions.
Also shows to be a 2 pole motor.

 

If I'm reading this correctly, it is rated 415V in delta:



If that's the case, then @Pyrex would be correct about the 720V thing, but you could still power it with a VFD but you wouldn't be able to go up to rated speed. You could follow the V/Hz line from 0V/0Hz up to 240V/33Hz and that would be the new max speed. You might have issues with motor cooling at 57% speed though. Worth a try if you're strapped for cash, but otherwise I suggest a new motor (one rated 240V).

 

The plate does not appear to show the details for the Delta connection?
The plate in #10 does show the Star/Delta options though.
Generally VFD's do not go that high a HP for 1ph supply versions.
Also shows to be a 2 pole motor.

 

If I'm reading this correctly, it is rated 415V in delta:

View attachment 295375

If that's the case, then @Pyrex would be correct about the 720V thing, but you could still power it with a VFD but you wouldn't be able to go up to rated speed. You could follow the V/Hz line from 0V/0Hz up to 240V/33Hz and that would be the new max speed. You might have issues with motor cooling at 57% speed though. Worth a try if you're strapped for cash, but otherwise I suggest a new motor (one rated 240V).
[ almost purchased this motor (see link) + freight it would work out to nearly double the vfd price, should have bit the bullet lol we shall see tomoz Anyway can you confirm that my initial drawing of the wiring is correct https://www.ebay.com.au/itm/1818468...RNe5laF/+FY6C7q5IPwqRU5bw=|tkp:Bk9SR8CctKOOYg

 

will give it a go tomoz ,can you confirm that my drawing of where the wires go is correct ? Assuming that it is a dual voltage motor

 

I see the company has been in business since 1936!
It might be worth a shot to send the an email question! They have a web site & contact request
https://www.cccme.cn/shop/cccme1205/contact.aspx

 

almost purchased this motor (see link) + freight it would work out to nearly double the vfd price, should have bit the bullet lol we shall see tomoz https://www.ebay.com.au/itm/1818468...RNe5laF/+FY6C7q5IPwqRU5bw=|tkp:Bk9SR8CctKOOYg

That is a single phase motor. If your goal is to not use a VFD, then yes, that will work directly with single phase mains but it will not work with the VFD. If you want to use the VFD then you need a 3 phase motor.

Honestly, the single phase motor will be simpler to implement and you might as well go that route. But if you want to use the VFD, let me know and I will address this:

Anyway can you confirm that my initial drawing of the wiring is correct

 

Мaximal voltage for this motor is 415 V
See PDF, page 12: