Thread: VFDs for Newbies

Brilliant - just brilliant! Many thanks, I'll check it out

Interesting read, even though I have three Phase, my sparky recommended using a VFD because of the control I will have, would have been a lot of mucking around to construct
otherwise.

Originally Posted by China

Interesting read, even though I have three Phase, my sparky recommended using a VFD because of the control I will have, would have been a lot of mucking around to construct otherwise.

YeP I agree, even if I had 3Phase Power in my shed I would still install VFDs on most of my machines.

I have a cousin in Italy who manufactures small electric motors. Many of his motors are 3P with built in VFDs for use in single phase situations. If he can recover from the COVID19 debacle he envisages phasing out single phase motors for all bar a few specialised situations.

So looking at what I have none of these motors are compatible with a VFD. Message from Conon Motors:

Its not right as your motor can only runs at 415V three phase then this single phase VFD is not right for you to use.
You motor should allows you to runs at either 240V/415V then you need change your motor to Delta mode (240V three phase). Then the motor is OK to run with single phase VFD.
Single phase VFD is 240V single phase input and three phase 240V output.

Motor	HP	Phase	Volts	AMPS	RPM	Cycles (Hz)	RATING
Crompton (Crescent Bandsaw)	2.75	3	400/440	5	940	50	CONT
K. L. Electric Co. (McPherson Bandsaw)	3	3	415	4.3	1425	50	CONT
Crompton (L.S. Barker Bandsaw)	5	3	400/440	7.4	1440	50	?

20200407_161426_resized.jpg 20200407_112921_resized.jpg 20200407_112926_resized.jpg

What a bummer - back to the drawing board in getting a Single Phase motor for my bandsaws

Originally Posted by Charlie_6ft

So looking at what I have none of these motors are compatible with a VFD. Message from Conon Motors:

Its not right as your motor can only runs at 415V three phase then this single phase VFD is not right for you to use.
You motor should allows you to runs at either 240V/415V then you need change your motor to Delta mode (240V three phase). Then the motor is OK to run with single phase VFD.
Single phase VFD is 240V single phase input and three phase 240V output.

Motor	HP	Phase	Volts	AMPS	RPM	Cycles (Hz)	RATING
Crompton (Crescent Bandsaw)	2.75	3	400/440	5	940	50	CONT
K. L. Electric Co. (McPherson Bandsaw)	3	3	415	4.3	1425	50	CONT
Crompton (L.S. Barker Bandsaw)	5	3	400/440	7.4	1440	50	?

20200407_161426_resized.jpg 20200407_112921_resized.jpg 20200407_112926_resized.jpg

What a bummer - back to the drawing board in getting a Single Phase motor for my bandsaws

The grey Crompton motor says it is 3Phase 400/440 ∆ so it simple cannot run at full power on 240V 3P and neither will conversion. If it is converted to Y it will need 690V to run at full power
The other two don't say whether they're ∆ or Y. If they're Y it may be possible to converted them to ∆ which will make them 240V 3P motors. This is s jb for a motor rewinder. Just bear in mind that if you take them an old motor they may not be prepared to convert an old motor.

I do not recommend using one VFD to operate two different motors unless they are the same speed and HP, the same performance is required of both motors, and suitable precautions taken using cross over switches etc. The technicalities are explained in that VFD for newbies doc.

As nearly as I can make out, the nameplate of the K.L.Electric motor shows "stator conn" as being star (lower RH corner). If this is the case, you could be in luck.

Chas.

Originally Posted by Chas

As nearly as I can make out, the nameplate of the K.L.Electric motor shows "stator conn" as being star (lower RH corner). If this is the case, you could be in luck.

Chas.

Good eyes chas

Thanks all - I think for the cost and trouble I would go to a ~$200 3HP single phase motor is looking pretty attractive.

Last time I took in a motor for testing (to get specifications as the plate was damaged) it cost me $120 and didn't even end up using it. Rewinding etc as far as my knowledge goes isn't cheap either.

So with none of my motors for the saws I have being compatible with a VFD I am exploring the option of being patient and waiting for an old motors like Crompton Parkinson that are compatible with VFDs to come up on Gumtree/eBay/FB Marketplace. I've found one but transport would make it cost prohibitive. The funny thing is I am sure there is probably 100s of motors suitable within a 150klm radius that are probably in the back of sheds just collecting dust going unused awaiting for eventual scrapping.

Like this one: A.C single phase cap start motor | Other Home & Garden | Gumtree Australia Mitchell Area - Seymour | 1241173157 which would have been perfect!

Screen Shot 2020-04-17 at 11.05.14 am.jpg Screen Shot 2020-04-17 at 11.05.27 am.jpg

Aside from Gumtree/eBay/FB Marketplace would there be any other options where I could find these old donks?

Just Heads up that single phase motors won't work on a VFD, some might run but they won't be very efficient.

Also some really old motors don't play all that well with VFDs. At the mens shed we had a Drill press with a big 1HP motor on it similar to the one in your post above. When I hooked it up to VFD it squealed and whined if i took it above about 60Hz. This has something to do with the magnetic characteristics of older type motors. The other thing is the bearings on these old motors might not be rated for higher speeds.

Originally Posted by Charlie_6ft

Rewinding etc as far as my knowledge goes isn't cheap either.

I got the star point brought out on three motors for a total cost of $80. I pulled the motors apart and just took the stators in.
This was at a random motor rewinders that I looked up and found the closest one to my house at the time.

Bit of a pipe dream trying to stick to old motors by the looks

Well the good thing is I'm not in a hurry as the saw restoration will take me quite some time - the motor being one of the last things I need to worry about.

Originally Posted by NCArcher

I got the star point brought out on three motors for a total cost of $80. I pulled the motors apart and just took the stators in.
This was at a random motor rewinders that I looked up and found the closest one to my house at the time.

Yep I had my 50+ year old motor converted for less than a hundred bucks on my jointer, took them a day. And they were really impressed with how well it ran, said they wouldn't be able to find something made to that calibre these days.

I was given a couple of 3 phase dust extractor units. How do I tell if they are suitable candidates for VFD to run of my single phase power supply?

Or do I need to get them checked by a suitable sparky?

These are the plates on them.

Regards,
Ray


20200422_085756.jpg20200422_085738.jpg