Thanks: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 16 to 20 of 20
-
28th Nov 2013, 10:57 AM #16
I think you are right.
Hi Ueee,
I still have the sheet somewhere, as my unit had a specific name.
Yes, I believe that is what it is, but had to look up vfd.
Look, I could not be happier with this Unit. It sits on 3000 RPM. most times I use The Lathe, It also has a Fan, & on a warmish day it will cut in, & just keeps going.
Had some initial probs after the Leccie had wired it up, as it made all kinds of noises.
I rang SEW in Tullamarine, spent about ˝Hr. pushing Buttons, & then all of sudden away it went.
So I get 3006 RPM from it,& stops in approx. 3 Secs.
What more could one want, besides a bit more power, but one gets used to what one has.Regards,
issatree.
Have Lathe, Wood Travel.
-
28th Nov 2013, 11:41 PM #17Diamond Member
- Join Date
- Oct 2008
- Location
- N.W.Tasmania
- Posts
- 1,407
Hi Chris, thanks for setting me straight here, although I was reasonably confident that a small motor like that of a coolant pump would probably cause no problem for a VFD running a much larger motor driving a lathe spindle for example, I did not realise that it was possible to run machines such as lathes, grinders and bandsaws from the one VFD with random switching of the various machines. Everything that I have read on the subject gave me the opposite impression. It just seemed that a random switching on or off of another significant load on the VFD would trigger a fault indicator, which would shut the whole lot down. If I understand you correctly, it would probably still detect the event, but you can program out its ability to use that input to shut down. That certainly makes the argument for the VFD pretty compelling. One remaining advantage the RPC would have is that machines like lathes and mills with their own inbuilt electrical controls, could be left as is, and would not need rewiring to make the switching on the machines work as inputs to the VFD.
How does the separate motor protection system work? I am familiar with the old technology contactors with heaters, which if they got hot because of excess current draw from the load, would activate a bimetal mounted contact to cut the power, but now we need a control input to the VFD, and not simply opening the circuit between the VFD and the load. I presume that there are adjustable current sensors to do this but I have not come across them at all, or is there some other clever method to give motor protection? Thanks again for the knowledge update,
Rob.
-
29th Nov 2013, 09:13 AM #18Cba
- Join Date
- Aug 2007
- Location
- Melbourne
- Age
- 68
- Posts
- 1,410
Rob
Here an introductory article from a VFD maker about running multiple motors from one VFD:
VFDs Can Control Multiple Motors
You will find many more documents if you do a Google search for "VFD multiple motors".
> .... I did not realise that it was possible to run machines such as lathes, grinders and bandsaws from the one VFD with random switching of the various machines......
If random switching is required, you must oversize the VFD by at least a factor of 1.1, better a little more. Example: if you had two 1HP motor and one 2HP motor, the tolat being 4HP, you would choose the next size up VFD of 5HP. Thius is so, because there will be quite an inrush current when adding a 2HP motor to two already running 1HP motors, and the VFD cannot slowly ramp up the added 2HP motor.
> ...... One remaining advantage the RPC would have is that machines like lathes and mills with their own inbuilt electrical controls, could be left as is, and would not need rewiring to make the switching on the machines work as inputs to the VFD.......
That is correct. Because in this case you are NOT controlling the VFD, you are just adding or removing loads from the running VFD.
>........ How does the separate motor protection system work? I am familiar with the old technology contactors with heaters, which if they got hot because of excess current draw from the load......
Individual motor protection is exactly as is used to be in the times before VFD. Just the same as if using a phase converter.
Rob, it is not that I think running several machine tools from one VFD that it is a particularly smart thing to do. I jst wanted to point out that it is perfectly feasible. And it is done in industry. Probably not to run machine tools, more like to run fans and pumps. For machine tools, I strongly recommend individual VFD's, if only for the invaluable advantages of induvidual variable speed, ramp up/down, braking.
But if someone really wants to go the old fashioned way, it is good to know that there are not only phase converters or rotary converters - a single VFD can perfectly serve as well for this purpose. And may nowdays be even cheaper. Chris
-
29th Nov 2013, 05:18 PM #19
I may be mistaken, but it looks like a simple static phase converter. I run all my 3 phase machinery off a similar system (and at 480V at that) and I can assure you that the dire consequences have not eventuated. The only rider I would put on it is that all of the motors are decent brands, and not cheap chinese ones.
I run a 5+1HP panel saw, 3HP dust extractor (together) and a 3HP metal lathe.Cheers.
Vernon.
__________________________________________________
Bite off more than you can chew and then chew like crazy.
-
30th Nov 2013, 05:39 PM #20Pink 10EE owner
- Join Date
- Aug 2008
- Location
- near Rockhampton
- Posts
- 6,216
Similar Threads
-
SOLD: 3 Phase 240V/415 0.75KW motor
By Ch4iS in forum METALWORK - Machinery, Equipment, MARKETReplies: 6Last Post: 14th Jun 2012, 05:51 PM -
VFD for 240V single phase motor
By neksmerj in forum METALWORK GENERALReplies: 2Last Post: 25th Feb 2011, 07:13 PM