Thread: VFD questions from an electrical idiot

Originally Posted by rtyuiop

Deciding factor might be if I can find a sparky who knows something about VFDs and will work for a reasonable rate.

Any sparky will be able to do wiring and connections for your VFD when they are installing the 15A outlet. The programming and understanding the requirements of the motor windings needing to be in a delta config as Bob has stated is where I reckon most residential sparkies may be found lacking due to little or no experience with motor control.
If you can program and configure the unit yourself, you will save yourself some dollars and once you get the motor, post a pic of the internals of the terminal box.

Originally Posted by maxxsinner

Any sparky will be able to do wiring and connections for your VFD when they are installing the 15A outlet.

Unfortunately that has not been my experience.
There's no doubt some sparkles already know how or are more than savvy enough to read the manuals and work it out for themselves.
However,
The young (30ish) sparky I bought my used 3P compressor from had not even heard of VFDs.
When the next door neighbour sparky came for a shed tour he said he had heard of VFDs but he would not know how to wire one up. When I offered to show him how, he said don't bother as he would just call in a more experienced sparky to do it.
At my mens shed I had to show our very experienced (50 years) shed sparky how to wire up a VFD.
When I recommend men's sheds get a 3Phase motor and VFD for their dust extractors I often get a call from their sparky asking questions about VFD that tells me they know little or nothing about them. Most work it out but I have still had to go and show a couple of sheds how to program their VFD.

Originally Posted by rtyuiop

Looks like he is in the US? That gives me pause...

Jack's a carpenter/joiner in Canada. He decided to equip his workshop(s) with mostly older British machinery (mostly Wadkin) and jokingly calls one shop the "Wadkin Temple". He's well known for having done the the greatest Wadkin PK (dimension saw) upgrade ever. He's a member here. Each year he holds an open day - the Rustfest:

Rustfest 2019 at the Wadkin Temple Canada

Cheers, Vann.

You are right Bob. Seven or so years ago when I wanted to have a 3Ph Rotary Converter I found most sparkies did not have a clue even with as much information as I had gathered. A Forumite 70 miles away volunteered to put all the bits together for me. One fellow I asked, told me it would not last very long and would probably result in a fire. His answer was to buy a petrol powered generator to get 3Ph.

My set up with the rotary is running trouble free and can deliver enough grunt when the machine is loaded up and working hard.

There are no doubt many sparkies in OZ that know all about VFDs but it's unlikely you will find them undertaking domestic wiring . The most likely places sparkies with VFD knowledge will be working are in industry but they are unlikely to be interested in wiring up a VFD for a single customer.. One of my relatives is a mechanical engineer specialising in mining equipment and he knows about them (on paper) as he stipulates them in many mining designs and apps. He's never had to wire one up but would be savvy enough to follow a VFD manual. He has an extensive home workshop but has never had any interest in installing one for himself.

Despite this sparkies are very useful (even essential in any electrical install) because the usually should the regs and therefore what can or cannot be done, so what they say does need to be taken very seriously

Question for the brains trust - talking to a sparky today who says he works with VFDs a lot (and he didn't say anything that was so obviously wrong that I could detect it!)... He says that motor is 415v only (unusual according to him) and won't run off the 3 phase 240v which is output from a single-to-3-phase VFD. Any thoughts?

Not a complete disaster if he is correct, I can just connect to 3 phase - I'll just lose the ability to move it around the shop between GPOs.

Originally Posted by rtyuiop

Question for the brains trust - talking to a sparky today who says he works with VFDs a lot (and he didn't say anything that was so obviously wrong that I could detect it!)... He says that motor is 415v only (unusual according to him) and won't run off the 3 phase 240v which is output from a single-to-3-phase VFD. Any thoughts?

Not a complete disaster if he is correct, I can just connect to 3 phase - I'll just lose the ability to move it around the shop between GPOs.

In that case its probably a 3Phase 415V ∆, one of those that cannot be converted without a complete motor rewind. It would be interesting to see the name plate on the motor to confirm this.

I'll take some photos (and open up the connection box) tonight.

Thanks Bob!

Originally Posted by rtyuiop

...He says that motor is 415v only (unusual according to him) and won't run off the 3 phase 240v which is output from a single-to-3-phase VFD. Any thoughts?...

You can get VFDs that transform 240v to 400v and convert to 3-phase - but they're more expensive (considerably more I believe).

Originally Posted by rtyuiop

...I'll just lose the ability to move it around the shop between GPOs.

Why not get more 3-phase outlets installed (or like me, run a 3-phase extension cord)?

Cheers, Vann.

Originally Posted by Vann

You can get VFDs that transform 240v to 400v and convert to 3-phase - but they're more expensive (considerably more I believe).

Why not get more 3-phase outlets installed (or like me, run a 3-phase extension cord)?

Cheers, Vann.

The sander and my dust extractor are the only three phase machines I have - and the dusty is outside and doesn't move! And 3 phase outlets and gear aren't all that cheap...

Photos:

Either your sparky doesn't want to get involved or doesn't know much about VFDs but that is definitely a convertible motor (I have a similar WEG 3kW motor on my DC but mine isa 2850 rpm - 2 pole motor).
Your motor is wired as a Y and it's just a matter of rearranging the brass connections between the terminals to convert it toe 240V ∆.

It's a matter of rearranging the brass strips (there will be 3 of them) marked by the red marks and connecting them .
Please don't attempt this yourself and get your sparky to do it.
VFDMotor.jpg

These WEG motors are very common and widely used on water Pumps and fans with VFDs.

I also notice your motor is 1430 rpm motor. In that case a VFD is really worth having so the speed can be boosted to 150 or 175% for belt work.
Does the machine have a disc as well as a belt?
Although you will have to be a bit more careful about not overheating the wood you'll find its MUCH faster with a fresh sanding belt than running at 1430.

For shaping work I sometime run my 3HP sander up to 3200 rpm using zirconia belts - makes a lot of dust but fair rips things into shape.

Originally Posted by rtyuiop

The sander and my dust extractor are the only three phase machines I have - and the dusty is outside and doesn't move! And 3 phase outlets and gear aren't all that cheap...

Check on Ebay, I think you will be surprised at how cheap they can be even for known brands such as Clipsal.

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