Thread: VFD Circuit Diagram Question

Originally Posted by Oldneweng

Joe's SPL stop switch is momentary. It would be released as soon as you take your finger off the button. The VFD will then automatically reset when it reaches zero Hz. Remember I deliberately tested this action this afternoon.

Thanks Dean,
I haven't used any 3 wire setup.
This fixes Joes braking issues correct?

I think we are getting the odd crossed wire between what Joe wants and what you.

Stuart

Originally Posted by jhovel

Just to report that I have edited my previous post. The diagram labels have changed a little and have headings.

The circuit was fine as it was.

I sent the question about different decleration and DC braking settings for the 04 & 13 parameter assignments to a new contact at Hyuria, one of the main manufacturers in China. Let's see if that person can find out.... There are 4 different settings possible - No.1 is 'normal' behaviour related to RUN commands, No.4 is related to JOG commands. As far as I can make out, No.2 and 3 are accessible only via RS485... maybe not.

Gotcha.

The circuit was fine as it was.

Except for Pd047 and Pd047.

I have a working setup. I am not about to change it in a hurry. I will have a play one day, but I have spent a lot of time on this recently and I need to devote some time to other jobs. I would like to actually use this lathe. It runs so smooth and quiet. The first job will probably be rollers for machine skates. I have not had access to a working lathe for many months.

Stuart. I did not assume you used a VFD. Now I know. I still don't understand why you say you don't use E/Stop circuits, but you still have a "Normal Off" ("Normally Open"?) switch for the foot brake pedal / E/Stop. This is what cba is talking about. A "Normally On" ("Normally Closed") switch is a fail safe. As cba stated, any fault and the entire system won't work. The switch for a fail safe circuit is "Normally Closed". Nomenclature mix up?

Dean

Originally Posted by Oldneweng

but you still have a "Normal Off" ("Normally Open"?) switch for the foot brake pedal / E/Stop.

lol ok I think we got there this time.
No not "normally open".
"normal off" i.e. the way I turn the lathe off normally........ I wasn't all the happy with the wording.... seems I was right to worry. Sorry about the confusion.
So on my lathe, I normally use the brake pedal(which is how I plan on turning it off in an emergency).. On my mill I normally use the E/stop button which turns off the powerfeed as well but does not use the NO circuit of the VSD.

Hope I've cleared up my mess.

Stuart

Originally Posted by Stustoys

lol ok I think we got there this time.
No not "normally open".
"normal off" i.e. the way I turn the lathe off normally........ I wasn't all the happy with the wording.... seems I was right to worry. Sorry about the confusion.
So on my lathe, I normally use the brake pedal(which is how I plan on turning it off in an emergency).. On my mill I normally use the E/stop button which turns off the powerfeed as well but does not use the NO circuit of the VSD.

Hope I've cleared up my mess.

Stuart

Ok. So you were talking about actions, not switch types. All clear now.

I have made so many changes in the last few days, I keep wondering if I have screwed up again. The lathe works perfectly. All is good. I can't wait to get some time to play with it. It is still sitting up on timbers about 200mm above the floor. Maybe I could stand on pallets or something like that. This will be the first good lathe I have had to play with in over 20 years.

Dean

Hi guys

I hate to interrupt but have come to the conclusion i need to get on board with a 2.2 kw unit and as you blokes seem to have a handle on it can you please recommend a supplier ???

My De Valliere 140 needs to be up and running and i just cannot afford the 4k quoted to get the 3 phase on i will be starting my own thread latter on the conversion.

My braking can still be done by the original brake on the motor as its 24 volt etc and run off a transfomer

Thanks Gents Bruce

Look, the Chinese HY here:
http://www.ebay.com.au/itm/111007644616
is as good as any at this end of the market - but this one comes with a Quality assurance certificate for a medical steam sterilizer! SO it must be good....

The next level up would be a Delta VFD like this: http://www.ebay.com.au/itm/221224559980
They are made in Taiwan and have a certain amount of quality control applied in design and manufacture.... at about double to cost.
This one is actually in Turkey, but you can get them anywhere.
or another Taiwanese brand one from Melbourne http://www.ebay.com.au/itm/281044149461 with a remote! (they also have one without a little cheaper....

Next up the food chain might be a Teco or a Eurotherm at about double that again. e.g. http://www.ebay.com.au/itm/110965795747 (you would be able to negotiate a better shipping rate).

Thn there are the Siemens, Telemecanique etc of the world of industrial control electronics - about double again.

My personal view is that in a hobby shop where you can afford a little down time - if the thing fails - you can buy 8 HYs before you hit the price of a Siemens....

thank you so much for the update Joe

Order is in for a China HY

Bruce

Originally Posted by jhovel

.............My personal view is that in a hobby shop where you can afford a little down time - if the thing fails - you can buy 8 HYs before you hit the price of a Siemens....

Fair enough. I would be more worried about the hobby shop burning down than about the downtime .

For me, I rather go with a "New Old Stock" brand name VFD. Or a lightly used brand name VFD.


From time to time, I fall in the trap and buy Chinese because it is soo much cheaper. The last purchase was a brand new diesel generator. I did read that with some tender loving care they can last 1 or 2000 hours...... It lasted just 45 minutes, I was gently running it in at 20% load.... then the stator winding shorted out. Bad luck, it probably only happens to one in ten. Grrr.... the warranty is parts only, exchange at depot. Care for a pic?

1.jpg2.jpg3.jpg

Originally Posted by cba_melbourne

Fair enough. I would be more worried about the hobby shop burning down than about the downtime .

My fire risk assessment of using chinese VFDs would be to put them at about the same level as all other chinese machinery and chinese power tools, especially as they are usually not used as unattended devices.

As far as I'm concerned there are far more significant fire risks in hobby sheds that folks should be worried about than the quality of machinery.

Some of you may have seen this poll
https://www.woodworkforums.com/f54/fire-safety-sheds-182251

Note that I did not include "consider buying equipment from reputable source" as worthy of consideration as a significant fire preventative measure.

The stat that only 28% of respondents have a shed structure that is designed to suit the risk of a fire is something to worry about.

Ha I'm more worried about the oxy acetylene set / 5 motorcycle tanks of petrol and 10,000 and 1 tins of aerosol in my shed than an attended piece of computer gear on my lathe that will let out magic smoke if it goes pear shaped

Thanks all Bruce

I was talking to one of the sparkies at work yesterday. I was asking him about switch spacing for the VFD. I commented on the "Normally Open" switch requirement for the E/Stop. His reply was that it is normal practice with all PLC's to use that convention.

In regards to a similar matter, we have a problem with remote switches sometimes, when they are mounted in portable housings which have been dropped. The stop switch can pop off the back of the button section (probably other switches too) with the result that the pump will not switch off. I have had the situation where I had to turn off the power at the socket. A normally closed switch does not help in this situation.

Dean

Originally Posted by Oldneweng

I was talking to one of the sparkies at work yesterday. I was asking him about switch spacing for the VFD. I commented on the "Normally Open" switch requirement for the E/Stop. His reply was that it is normal practice with all PLC's to use that convention. .................

Emergency and safety circuits should always be wired to the PLC using normally closed switches. This is to make sure that if a wire breaks or otherwise comes out of its contact, the circuit will be active (or fail safe). In a PLC it does not matter if you use a NO or a NC contact, the program does not care. You do not even think about NO or NC, you rather think of an input being "true if high" or "true if low". Besides, I believe it is regarded as bad practice to wire safety circuits directly into a PLC.

One should not use NO contacts for safety circuits, with one exception. There are situations, where even a safety circuit made with NC contacts in series is not regarded as sufficiently failsafe. This is when the possibility exists, that the wires of the safety circuit may be shortened together. In this case you would wire both NO and NC contacts and have the PLC compare both signals.


In your particular case at hand, where the VFD apparently only has a "true if high" emergency stop that cannot be reprogrammed, you could consider two things to invert the logic and still use NC safety contacts.
- use a relay in between the input and the NC contact
or
- wire the e-stop input with a pull-up resistor to the common + supply, as well as to the NC contact.

Originally Posted by Oldneweng

I was talking to one of the sparkies at work yesterday. I was asking him about switch spacing for the VFD. I commented on the "Normally Open" switch requirement for the E/Stop. His reply was that it is normal practice with all PLC's to use that convention.

In regards to a similar matter, we have a problem with remote switches sometimes, when they are mounted in portable housings which have been dropped. The stop switch can pop off the back of the button section (probably other switches too) with the result that the pump will not switch off. I have had the situation where I had to turn off the power at the socket. A normally closed switch does not help in this situation.

Dean

No. normally e-stops and safety interlocks are wired in a loop so that any break in the loop will stop the machine. Maybe he misunderstood the question? Also, resetting after an e-stop must require two seperate actions, not just resetting the e-stop, usually, it's reset the e-stop, and then press a reset or power on button, the machine shouldn't restart when just the e-stop is reset. Most systems go one step further and have series latching contactors on a second e-stop loop.

As far as the remote switches, sounds like they are using the wrong type of switch. If the switch pops off the stack it should open and stop the pump.

Ray

EDIT: I see Chris and I posted at the same time... with similar comments..

Originally Posted by cba_melbourne

Emergency and safety circuits should always be wired to the PLC using normally closed switches. This is to make sure that if a wire breaks or otherwise comes out of its contact, the circuit will be active (or fail safe). In a PLC it does not matter if you use a NO or a NC contact, the program does not care. You do not even think about NO or NC, you rather think of an input being "true if high" or "true if low". Besides, I believe it is regarded as bad practice to wire safety circuits directly into a PLC.

One should not use NO contacts for safety circuits, with one exception. There are situations, where even a safety circuit made with NC contacts in series is not regarded as sufficiently failsafe. This is when the possibility exists, that the wires of the safety circuit may be shortened together. In this case you would wire both NO and NC contacts and have the PLC compare both signals.


In your particular case at hand, where the VFD apparently only has a "true if high" emergency stop that cannot be reprogrammed, you could consider two things to invert the logic and still use NC safety contacts.
- use a relay in between the input and the NC contact
or
- wire the e-stop input with a pull-up resistor to the common + supply, as well as to the NC contact.

I am waiting to hear from Joe to see if swapping the Stop and E Stop connectors works ok.

No. normally e-stops and safety interlocks are wired in a loop so that any break in the loop will stop the machine. Maybe he misunderstood the question?

I don't think he misunderstood, and please don't shoot the messenger.

My VFD and Joe's VFD both use

"Normally Open" switch requirement for the E/Stop.

So there must be some truth in this.

Maybe I should have said "it is normal practice for all PLC's to use that convention". It was 2:30am when I wrote this. He was talking about what the PLC does, not how it is connected. I guess what I am saying is that this convention is accepted as far as he is concerned. He is also required to follow the rules and regs, and accepted practice for the workplace. This may be different from Best Practice.

How the rest of the equipment is connected up is going to be a different kettle of fish I guess. The majority of VSD's are only connected to pumps, which do not represent a big safety issue in comparison to big rotating machines, all of which are protected with every safety device known. These machines also have reset switches which must be pressed for the machine to restart.

As far as the remote switches, sounds like they are using the wrong type of switch. If the switch pops off the stack it should open and stop the pump.

Maybe that is so. They are only stopping pumps. The power switch/socket is close by. I am by no means an expert in this matter. The E Stop switch I have came off the lathe. It was used with contactors. There are 2 pieces. The button which is attached to the housing with a threaded locking ring. The electrical switch which clips/screws onto the button piece. This is activated by a pointed plastic bit which just pushes on the switch pin. The stop switch I bought is the same except it is not latching. This is the only type of switch I have seen. You are saying that a Stop switch should lock into the button part?

Obviously the lathe is a machine that requires the best E Stops available. I am hoping Joe will report soon.

Dean