Inverter Remote Stop button.

Hello all, just fitted an inverter to a lathe, a Jaguar Cub 2.2kw unit. I want to fit just an emergency stop button near to the old switches ( all now redundant ), but not a complete pendant. My understanding is that to use a remote pendantyou have to re-programme the inverter to be able to do this, so that control passes to the pendant, or can you still use the buttons on the inverter as well ?. Would I have to "re-programme" the inverter to just fit a Stop button ? I realise, that after hitting the said button and releasing it so too speak, the motor will start back up, which Im not to worried about, I just want to be able to hit the remote button in an emergency.

l realise I could just fit a complete remote pendant with reverse/forward, jog, potentiometer etc, but I cant really use them on this lathe.

Many thanks, Roger.

Hi Roger,
If you can post information from the manual on the instructions to connect a remote pendant and the schematic (If possible) of the pendant myself and others may be able to help you. I assume the pendant has a stop button, a start button and a speed control pot. Is this assumption correct ?

Les.

Roger,

I have a Siemens 420 inverter for my lathe, we use these inverters on equipment at work, if you program the unit to work with a remote my inverter switches off the buttons on itself mainly to stop incorrect use of the wrong buttons.

Martin P

My emergency stop button is on the mains power line into my inverter. Works a treat, no need to mess around with the inverter programming.

But after you have hit it don't forget to unlock it again afterwards .

Jo

Roger

Jo has just reminded me that the EM stop must be inserted in the incoming supply but not directly, its needs to operate a contactor which carries the supply to the inverter so that if the stop is pressed it cannot just reset incase the inverter starts the motor immediately it needs a switch to reinstate the contactor once the problem is sorted, you can use another pair of contacts on the EM stop to inform the inverter the stop has been pressed.

Martin P

Thanks all, ive got a remote pendant diagram that Brian O'Connor kindly sent me so I will try and post it, which might be unsuccessful !. So it seems that either method, ie, remote button on the inverter control side or in the power feed to the inverter, via a contactor,does roughly the same thing. Theres no braking facility in the inverter.Im leaning towards Jo's method !. Sounds a good idea. Again, many thanks.

PS, it must be my tiny brain, ive tried to upload a photo from my computer, but all I seem to get, is " select one from your album", so ive tried to upload it into my "album", to no avail. However, it may emerge as my Avatar !

Deleted

Geoff - Posting before thinking! 

Edited By OuBallie on 18/02/2014 14:30:55

Mine just has a twist lock stop switch in the power line that are about £5 on Fleabay.

An inverter should never start up immediatley that mains power is applied to it under any conditions: it should have internal contactors to prevent this and any power loss will force you to hit the start button again.

Jo

Les Jones 1, heres the diagram, I hope.

Edited By Roger Williams 2 on 18/02/2014 15:33:08

Any e-stop that breaks the supply must be in the 240V supply, as breaking the 3-phase connections can damage the inverter.

There are lots of ways to wire up the jaguar Cub, I've come up with a scheme that doesn't use any relays and provides a normal stop (gentle ramp down) on a small red button and a coast to stop (stops the inverter like an e-stop) on athe big red mushroom button.

I have almost written this up for MEW but was waiting until I had moved it into the old control housing for my mini lathe (together with a 0-100% power meter).

As I ought to make space for others in MEW I'll put it up as a thread in this forum and update it when I finally change from pendant to control box.

Neil

Hi Roger,
I was hoping that you also had the instructions for connecting the pendant box and that they suggested removing a link which would then be connected to the pendant stop button. The fact that the pendant box also contains the relay means it does not work in the way I expected. It sounds like Neil has already worked out how it works so I suggest waiting for the solution from him.

Les.

Hello Les, Ive downloaded the official manual, theres no mention of seperate E stop buttons, only complete pendants, and then, no real instruction for those either.However, Transwave sell pendants, and also give free instructions for their fitting, but I dont want all the remote functions, just one big red button ! So I will wait for Neil to come up with his methods. Regards, Roger.

Hi Roger if you want just one big red button then as said previously in needs to go in the 240v feed to the inverter, and only used in a emergency to cut the power to the inverter.

H

This kink may help http://www.as-uk.co.uk/downloads/manuals/imo_cub_cm.pdf 

Edited By Harry Wilkes on 18/02/2014 22:06:38

Harry, thanks for the link, its the same as one I have. The Transwave pendant instructions give the details on all the connections, and then state, " if there is a requirement to fit additional stop buttons, connect them in series to interrupt the pink 24dc + supply wire. " But it seems I need a complete pendant to be able to do that !!! Or it does to me anyway. Regards, Roger.

Roger I think you will find those instructions are refering to additional stop button/buttons ! A stop button is not the same as a emergency stop button, the difference being a stop button will stop the drive in thev proper manner e, g allowvthevdrive to run down and stop the emergency stop will cut power to the inverter and should only be used in a emergency. So is it an additional stop button you want to fit or e/stop ?

H

I'm not 100% sure but I thought that most inverter drives do not like having their supply cut off abruptly while running. Mine certainly says that there should not be any disconnection device between it and it's supply.

There is usually a way to setup the 'pendant' or 'multi-input' controls for a variety of functions, run, stop, em.stop, etc. These can then be used with simple pushbuttons to make or break the appropriate circuits across them.

There are four ways of 'stopping' an inverter powered motor.

1 An e-stop button before the inverter. This makes the motor coast to a stop and kills all power. It can damage the inverter, but is 100% guareanteed to cut all power.

2 Use the coast to stop function of the inverter. This works exactly as an e-stop but leave the inverter live. It can be wired to work from a 'break' switch so existing e-stop buttons can be used as well as limit switches etc. I have impemented this and it works. The stop is very sudden with my setup.

3 Fit a resistive brake to the inverter. This will more or less short the motor and it will stop dead. This is MUCH faster than with an e-stop, especially for machines with a lot of rotational inertia. It will leave the inverter itself live. This can be wired to be operated by e-stop and limit switches. I have not implemented this.

4 Use normal soft-stop buttons. This causes the motor to slow down gently to a stop over a preset period.

My approach is to use 4 for normal working as gentle stop/start helps avoid motor overheating and is less fraught. I use approach 2 for e-stop as it is very fast with my machine. The cautious would take approach 1 and in indiustry i'm sure they would use number 4 - active braking - to get the fastest stop possible.

Neil

Neil,

Option 3 should never be used with a lathe that has screw-on chucks such as Myford because instantly stopping the spindle could make the chuck spin off in a very dangerous manner.

Resistive braking is mandatory on certain industrial wood working machines that cannot be totally guarded due to the work they have to do. Circular saws, spindle moulders are obvious examples.

All that has to be done is to break into the wire from the start switch to the inverter board and insert a normally closed emergency stop into the circuit , thus the E stop will be in series with the normal stop switch. In this way the drive to the motor will be stopped in the way the maker of the inverter intended.

Eric

I'v just dug out an electrical drawing of one of my employers Industrial washing machines, we use a Siemens 420 inverter to drive a 7.5Kw pump, the reason we use an inverter is so that we dont expect the pump to go from 0 bar to 4 bar in one instance, we ramp the pump up slowly plus depending whatever the customer wants we can reduce the working pressure by slowing the pump down. We also have an extractor fan than runs at various speeds so we use a 420 .75Kw inverter to run that. The EM stop's is powered by 24 volts DC through a safety relay which when the relay is activated pulls in a contactor on the incoming supply, if an EM stop is actived the relay drops out disengaging the supply to the inverter. The safety relay also supplies a signal to the machine PLC so that an alarm can be generated.

Martin P

Helo again, the type of " e stop" I want, is the type that Rob c described, i.e, on the 24 v control side. It would just mimic the stop button on the inverter. I dont expect it to stop the motor dead. Just a switch near to the old off switch, which would have had a similar effect in stopping the motor.With this original stop button, the motor took a few seconds to coast to a standstill anyway.

I would have bought a pendant, but for £70, seems a bit steep when I will only use one button!. So I could obviously make a little unit myself, but I havent a clue how to wire just that to the control circuit.Just something to give me half a chance if anything went wrong !.Ive looked at the Newton Tesla and the Transwave pendants, and neither have a decent red knob to "hit".Cheers.