Thread: VFD for 1.1kW Coldsaw

Hi Guys,

Looking for some help selecting a VFD for a 3 phase coldsaw.
It seems to be driven by a 1.1kW single speed 3 phase motor.
I plan on powering it via a standard 20amp 240v single phase input.
Can someone please suggest a VFD capable of this achieving this task (on a budget).
I am assuming it can be a 240v single phase in 240v 3 phase out unit, given rewiring of the motor?

Here is a pic of the motor.
Motor2.jpg

Look forward to your responses,
THanks

A 1.5kW single phase to 3 phase VFD will connect straight to that motor. You just have to re-configure the terminals on the motor to connect it in Delta.
http://www.ebay.com.au/itm/PROFESSIO...27939814&rt=nc
http://www.ebay.com.au/itm/1-5KW-2HP...item3f3e496fe6
A quick search on eBay found these two but hunt around for a better price.

Originally Posted by bwah

Hi Guys,

Looking for some help selecting a VFD for a 3 phase coldsaw.
It seems to be driven by a 1.1kW single speed 3 phase motor.
I plan on powering it via a standard 20amp 240v single phase input.
Can someone please suggest a VFD capable of this achieving this task (on a budget).
I am assuming it can be a 240v single phase in 240v 3 phase out unit, given rewiring of the motor?

Correct - you will just need to switch around a few connectors inside the connection box and all should work.

VFD wise I would suggest a 2HP, 1.5kW would work on that motor quite nicely.
Does it have multiple speeds/gears?
Smaller units typically have 2 speeds 25 and 50 RPM.
If you left it in the slow gear you might not have to change the gear to get it to run at the higher speed - i.e. just run it at 100Hz?

Thanks for the speedy reply,
there are some cheapies on ebay such as
http://www.ebay.com.au/itm/1-5KW-2HP...item5d532d243b
just wasn't sure of the quality etc

single speed switch as far as im aware
would be nice to have ability to vary speed based on material im cutting
havn't looked to far into the capabilities of vfd's yet
just want to get it running first

Originally Posted by bwah

Thanks for the speedy reply,
there are some cheapies on ebay such as
http://www.ebay.com.au/itm/1-5KW-2HP...item5d532d243b
just wasn't sure of the quality etc

These look relatively new and are supposed to be vector drives,
This doesn't have much application to what you are doing but I am interested to know how good they are.

I was reading the info on those VFd's. It states that it supports open loop vector control. I'm confused, I thought the whole purpose of vector control is to have closed loop as in a feedback circuit to monitor it's speed?

Simon

Originally Posted by simonl

I was reading the info on those VFd's. It states that it supports open loop vector control. I'm confused, I thought the whole purpose of vector control is to have closed loop as in a feedback circuit to monitor it's speed?
Simon

There are two type of vector control Open and Closed.

Have a read of this for the broad details
http://machinedesign.com/motorsdrive...ol-method-vfds

The Wikipedia page on Vector control provides a dense/technical but interesting perspective.
According to that page the Algorithm used in Vector control is based on something discovered in 1929 called the Park Transformation which has been rated the second most important power engineering publication in the 20th century.

Can someone please confirm how the motor should be wired for 240v 3 phase output
Attached are pics of the wiring + switch front and back
Thanks

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Wiring.jpgSwitch.jpg

Originally Posted by bwah

Can someone please confirm how the motor should be wired for 240v 3 phase output
Attached are pics of the wiring + switch front and back
Thanks

Unless someone is familiar with that particular motor it's very difficult to just look at a junction box alike that and decide by photograph how to wire it up.
Usually the connection alternatives printed/stamped/cast on the back of the junction box lid.

I usually do all mine from first principles using an ohm meter - if R is the resistance of one coil, then a Y connected motor has a resistance between coils of 2R wheres a ∆ motor has a resistance between coils of 2/3R.

Hopefully someone will come along who has seen that particular motor before and can be more specific.

Don't just wing it, get further confirmation before connecting up

BTW the different coloured leads at the top look a bit dodgy to me - I would definitely get that checked out - Meggering the motor is also worth while.

Did you end up buying that VFD? If so did you get a manual and how easy is it to read?

Thanks for the quick reply

I ended up getting a huanyang 1.5kW, the manual isn't the best.. but there seems to be a fair bit of info on the net about parameters etc.
Not sure what parameters apply to my application yet, being a coldsaw i think it would be quite basic?

The dif coloured leads at the top of the photo are the original 3 phase input wires
from left to right: L1, L2, L3

Closer inspection of the photo shows the ∆ and Y symbols on the connection plate itself - see photo

The middle set of terminals looks like the common point that has conductive bridges between all 3.

Usually these metal bridges are reoriented by connection with their respective upper paired terminal and then the red wires (if they indeed the wires from the motor) are removed from the lower set of terminals and connected to the middle 3 terminals .

BUT stupidly it could also be the other way around - look under the lid of the connection box.

DO NOT RELY ON MY ADVICE ALONE - get further conformation before proceeding.
I cannot stress this enough.

Originally Posted by bwah

Thanks for the quick reply

I ended up getting a huanyang 1.5kW, the manual isn't the best.. but there seems to be a fair bit of info on the net about parameters etc.
Not sure what parameters apply to my application yet, being a coldsaw i think it would be quite basic?

Yeah in the first instance I would just get it running and slowly change things to suit your need.

The think you need to be careful with those HY VFD is to never trust the factory setting - some have max frequency set to 50Hz and others have it set to 400 Hz. The frightened the shyte out of me when it first happened. So make sure the max frequency is set to 50 Hz before you press the start button.

The dif coloured leads at the top of the photo are the original 3 phase input wires
from left to right: L1, L2, L3

They look like they have been pinched between the cover and motor housing - I would look at replacing those

how deceiving a photo can be..
i got the dslr out for closer inspection
what appeared to be a delta symbol was nothing and what appeared to be a star symbol was an X

Wiring2a.JPG

That is the main switch not the motor terminals. You need to see where the wires from that switch go too. It should then have other terminals you can connect to.
You do not want to connect the vfd output to that switch.