Emergency stop and VFD

[Trextr7monkey]

Hi I acquired a lathe with a VFD wired direct to the single phase motor which works fine. It completely by passes the original switch gear so I thought I could fit a mushroom head emergency stop in place of original switch but I’d read that running VFD with no load could damage it so I would like to check that the emergency stop should be fitted upstream of the VFD so that it stops everything. I don’t really want to get into lots of complications and disturb some thing that works fine at the moment but would very much welcome advice on this
Thanks

Pics show original switch which was on off and reverse and the VFD in question

 

[Myfordman]

Download the manual here
https://www.sdsdrives.com/download-...xEkH0CB99E15mocZc5TMkzs1rDZSPCJXDMKFS66vTnzmi

And that should help. The control inputs to the inverter should accommodate Estop nc contacts. Otherwise fit it in series with the stop button.
Never disconnect the motor from the inverter when is running

 

[ChaiLatte]

Never disconnect the motor from the inverter when [it] is running

For the sake of clarity, I am not sure if that is intended as general advice or if you think this might be something suggested in the above post.

The actual words are "fitted upstream of the VFD". Upstream of the VFD is on its input side. Hitting an emergency stop thus placed is no different to a power cut occurring.

You are correct that the preferred (best) place for an E-stop is on the VFD control circuitry, but we should have no potential misunderstanding concerning the OP's proposal.

 

[Trextr7monkey]

Thanks very much for the prompt replies I have a lot of reading to do

 

[Katomi woodsmith]

Don’t know if this will help
I use a foot switch in my work shop, it can be wired two ways
1 press down … power on all the time pressed down
2 power on all the time, press the foot switch and power is interrupted untill realised

 

[Myfordman]

What I wrote about motor disconnection is correct in virtually all situations. This is NOT the same as would occur under power cut situation when the inverter will manage the shut down of the motor safely.

 

[Katomi woodsmith]

Foot Switch, 10A Foot Operated Pedal Controller Switch,IP62 Aluminum Heavy Duty Electric Pedal Momentary Pedal Switch,Silver Alloy Contacts Nonslip Self-reset Foot Controller​

 

[ChaiLatte]

What I wrote about motor disconnection is correct in virtually all situations.

Writing something that is relevant and answers the question being asked is rather a different matter to writing something that is merely correct.

 

[Katomi woodsmith]

Me? Sorry.
I just posted another method that I thought would be a simple solution to OP’s question

 

[Fitzroy]

Fitting an emergency stop in the power supply to the inverter will likely be less effective at stopping the lathe than witting the e-stop to the inverter controller stop function. Inverters have large capacitors and although turning the power off to the inverter will result in the machine stopping you would need to look at the inverter manual to understand how fast etc.

 

[Spectric]

You are calling it an E-Stop but in reality this is just another Stop Button because it is diectly switching the operational system whereas an E-Stop should work through a safety relay that would have force guided contacts.

The E-Stop is also not a safety device, it offers no protection against any hazzard and is operated after the event often by a third party . So what is your reasoning for needing one because if something goes wrong, ie the workpiece departs the lathe it will happen much faster than you could operate the E-Stop and unless the machine is fitted with a brake then it will not stop rotating very quickly.

What I wrote about motor disconnection is correct in virtually all situations. This is NOT the same as would occur under power cut situation when the inverter will manage the shut down of the motor safely.

With a VFD it has to be connected to the load without any interconnects or switches otherwise with a VFD powered up and no load the output bridge can be destroyed, but in the event of a power cut the VFD no longer functions and cannot perform any control functions.

 

[Katomi woodsmith]

I put my switch peddle between my 2kw inverter and the lathe or the dust extraction. Lift my foot off and no power, the inverter is still on but no power to lathe

 

[Woodenhead]

To add further on the subject of motors and emergency stops, in a previous (industrial) life, it was common to see DC injection used to bring AC motors to a quick stop in an emergency situation.
With a typical AC motor, if you remove power it will continue to spin under inertia, which is where DC injection comes in. This has the effect of very quickly bringing a motor to a stop, over the gradual reduction of inertia plus any impact from body parts, tools lodged in workpieces, etc.

It could be that the VFD/VSD has this functionality incorporated within it, and needs an activation method? Otherwise further, more complex integration will be required.

More here: DC injection braking

If your lathe has a DC motor then, well, I'll get me coat!

Hope this is useful for general food for thought, etc

 

[Sideways]

Read the manual won't you all !
As @Myfordman, @Fergie 307 and others have said, when using a VFD you control it through it's own control inputs. You don't put an e-stop or a foot switch in the power supply to the inverter or between the inverter and the motor.

It shows that you don't know what you are doing.
It isn't anything that the manufacturer would recommend.
It might shorten the life of the VFD - @ChaiLatte and I had an argument about this in a previous previous thread.
(https://www.ukworkshop.co.uk/threads/hello-and-startrite.149523/post-1763405)
It deprives you of any active braking that your VFD is programmed to do.

Amateurs !

 

[Myfordman]

Read the manual won't you all !
As @Myfordman, @Fergie 307 and others have said, when using a VFD you control it through it's own control inputs. You don't put an e-stop or a foot switch in the power supply to the inverter or between the inverter and the motor.

It shows that you don't know what you are doing.
It isn't anything that the manufacturer would recommend.
It might shorten the life of the VFD - @ChaiLatte and I had an argument about this in a previous previous thread.
(https://www.ukworkshop.co.uk/threads/hello-and-startrite.149523/post-1763405)
It deprives you of any active braking that your VFD is programmed to do.

Amateurs !

I think the biblical quote that comes to mind is something like "Do not give what is holy to the dogs; nor cast your pearls before swine, lest they trample them under their feet, and turn and tear you in pieces."

 

[deema]

If you arnt competent with electrics, DO NOT touch them, don’t mess with them and don’t think that uTube of some forum will adequate prepare or teach you enough to be sufficiently competent to do anything with main electrics. IT WILL KILL YOU. Electrics doesn’t take any prisoners, it doesn’t have a smell like a gas leak, or have to reach a certain concentration like gas to become a hazard, it’s a lethal entity all the time. Why when nobody who isn’t registered messes with gas does everyone thing they can mess with electrics. The latter is far more likely to kill you.

 

[Fergie 307]

Read the manual won't you all !
As @Myfordman, @Fergie 307 and others have said, when using a VFD you control it through it's own control inputs. You don't put an e-stop or a foot switch in the power supply to the inverter or between the inverter and the motor.

It shows that you don't know what you are doing.
It isn't anything that the manufacturer would recommend.
It might shorten the life of the VFD - @ChaiLatte and I had an argument about this in a previous previous thread.
(https://www.ukworkshop.co.uk/threads/hello-and-startrite.149523/post-1763405)
It deprives you of any active braking that your VFD is programmed to do.

Amateurs !

Putting a stop in the power supply to the inverter would be a waste of time as any kind of safety feature. Cut the power and the vfd will continue to work for some time as it shuts down.
I use a Huan Yang inverter on my metal lathe. I can't recall without going out and looking at it what it's capacity is, but did overspec it at the time so it is designed to drive a bigger motor than my 3hp. Without any additional braking capacity added, as it came out of the box it will bring the machine to a stop in 3-4 seconds, depending on the speed and size of chuck. A ten inch chuck running at 100rpm stops almost immediately. 6inch at 1000rpm a few seconds.
At the end of the day the only way you are going to get an instant stop is by using the very powerful electro magnetic brakes you see on modern industrial machines.

 

[AutoDoc Williams]

Writing something that is relevant and answers the question being asked is rather a different matter to writing something that is merely correct.

 

[AutoDoc Williams]

Old steel mill controls guy here. E-stops are for electrical disconnects. They keep the poor user from being electrocuted. To protect against the mechanical gear killing the operator , a fast-stop (F-Stop) is what you're after when there's a VFD in the circuit. An F-Stop is an input to the VFD that tells it to go into a rapid deceleration to stop our lathe as fast as possible. In the old, non VFD days, all we had were e-stops and normally open brakes to grab rotational gear when power was lost. In our lathe situation here, we want an F-Stop wired into the drive with the proper parameters to stop that thing quick when the switch is actuated. To the OP, post up the make and model of the VFD and maybe me, or someone else here can sort it for you.