auto restart in the event of a power failure

[oliver]

Greetings all,

I am looking to make a circuit that will automatically restart an industrial machine
the problem is that there is a safety factor here and we need a siren to sound for at least 120 seconds before it starts the machine up again.

the machines in question has a push to make switch and we can use a relay NO to bridge the switch
we will have 220 v ac available so we can use a transformer to create any voltage we need

I will be extremely great full for your assistance with this project.

Oliver

 

[GreenGiant]

you may need to change a bit of the wiring but you should look into an "Auto Reset Safety Contactor" like an ABB RT6 series, for a way of turning it on once power has returned.

You can wire it so that nothing will turn on if a low voltage switch is not enabled, and you can set it so that when power returns it will automatically reset to the on position.

Now as for a timer, thats fairly simple, there are tons of timers that can do what you want we use this one where I work, not exactly how you want to, but it can certainly do it that way, you can use this in conjunction with this light, this siren, and this base to make a light and siren for anywhere from 10 seconds to 12 hours before it allows power to pass to the safety contacts.

there is a question of how much current are you going to need controlled?

 

[shrtrnd]

Having spent most of my working life in industrial electronics, my input is to stand back
and carefully evaluate what you intend to do.
The fact that you recognize the 'safety factor' here, should give you pause to think.
Defeating the manual restart may sound like a nice idea that makes life simpler for
people. What's the possibility of injury to workers or damage to the equipment if you
auto-restart this thing, without somebody physically looking at it first?
I'll leave it up the the others here to give you tips on how to do this.
My concern, is what happens if you do it, and somebody or something isn't ready for
an automatic restart.

 

[duke37]

What if the siren fails?

 

[GreenGiant]

Oh its definitely not recomended, especially with motors and things, Im just answering the question. We use the autoreset in a remote box that goes through another safety contactor that needs a physical button to be pressed in order to reset everything.

Duke, while I agree with your sentiment, you sometimes need to overlook these things, when entering the world of what-ifs you end up never doing anything, because there is always another what-if that could lead to problems.

 

[davenn]

............Duke, while I agree with your sentiment, you sometimes need to overlook these things, when entering the world of what-ifs you end up never doing anything, because there is always another what-if that could lead to problems.

You have to be kidding!!

NOTHING is more important than worker safety NOTHING

if there is any chance at all that this machine may fire up unexpectedly whilst workers are in the middle of it ... that is totally unacceptable

What is being proposed by the OP could result in a death. NEVER defeat the satety manual power up

Dave

 

[shrtrnd]

I don't think I need to beat a dead-horse here, I just want to share a story.
I was a lifeguard at a public swimming pool during the summers of my youth.
The City hired a handyman to handle the maintenance of the pool, so they wouldn't
have to pay a skilled, licensed city worker to do it (Yeah, it was a few years ago).
I was wandering around the pool one morning before we opened and I heard an "Aaahhh!"
from the opened door to the pump shack next to the pool. I started walking over to the
shack, 10 seconds later I heard another "Aahhhh!" from inside the shack.
I opened the door, the pump-room floor was covered in water, steaming water, when I
heard another "Aahhh!".
The handyman was lying inside the shack on the flooded floor, begging me for help.
I waitied the obvious 10 seconds for the next scream, then quickly (and stupidly, but
I was 16), ran in, grabbed the handyman and pulled him out of the shack.
The handyman had gotten tired resetting the pump control when it tripped, so he rewired the controller
to automatically reset itself 10 seconds after it tripped.
I know it's just trivia, but it's something I remember very well.

 

[GreenGiant]

You have to be kidding!!

NOTHING is more important than worker safety NOTHING

if there is any chance at all that this machine may fire up unexpectedly whilst workers are in the middle of it ... that is totally unacceptable

What is being proposed by the OP could result in a death. NEVER defeat the satety manual power up

Dave

That's not how I meant it, what I meant is even if you rely on a reset button what if someone is standing somewhere that they would be in danger and someone doesnt see that and hits the reset button.

Ok well now lets see, everyone has to give a radio "ok" in order for the guy to hit the reset button, what if there is interference somewhere and it gives a false sound of someone saying ok?

Ok lets see, there is a button outside of the system for each person who would potentially be working on in spaced so that no one person can hit all of them at the same time in order to reset it, what if there is a contracter inside the system that only the boss knows about and they hit the reset?

That's what I meant about the reset button, like at my work we have a system when someone goes inside our unit that they put it in service mode and take the key to switch it and then in order for the system to move they have to press and hold a live man switch, if they dont hit the live man within 30 minutes a timer goes off and the light/siren mentioned before goes off to notify that the person inside may not be conscious/alive, well to duke's point what if that fails? the what-ifs are stupid to a point. THAT was my point. You can spend all day going over what-ifs and end up 6 months behind with a 100 level redundant safety system and still have what-ifs that lead to possible death.


I was under the assumption that the system the OP was talking about was a custom built thing that he was looking to change, not an off the shelf thing.

 

[duke37]

To design a fail safe system will use a lot of what-ifs but this system described is fail to danger.

The machine could be guarded and all operators working inside the guards would have a padlock to isolate the power. Only when the last padlock is removed, could the machine be actuated.

I worked for a time on an X-ray set where the guards were detected with micro-switches. This was rejected as micro-switches can have wrong side failures. Everything should be evaluated.
In another case some special safety relays had been developed and used for many years but then some failures ocurred. This was due to the makers 'improving' the relays by using silicone insulated wire. The siliane vapour coated the contacts with insulating silica. No-one had asked what-if.
Elf and sayfty have often been derided but I would not like to work with the safety systems of one hundred years ago.

 

[davenn]

Ok well now lets see, everyone has to give a radio "ok" in order for the guy to hit the reset button, what if there is interference somewhere and it gives a false sound of someone saying ok?

Ok lets see, there is a button outside of the system for each person who would potentially be working on in spaced so that no one person can hit all of them at the same time in order to reset it, what if there is a contracter inside the system that only the boss knows about and they hit the reset?

OK Im going to put this in bold red cuz its just too important to ignore

You are obviously unaware of safety procedures when working on electrically powered equip

There are things called isolation/lockout tags. These are used BY THE PERSON doing the repair/maintenance work on the gear
ONLY that person has the power to remove the tag from the disabled power circuit

Power CANNOT be restored to the equip UNTIL the person who placed the isolation tag removes said tag

This is to stop other people restoring power. There are huge penalties for anyone removing lockout tags that they didn't place. These and related issues are usually always discussed in company safety meetings to make sure ALL staff are aware of the consequences

I was under the assumption that the system the OP was talking about was a custom built thing that he was looking to change, not an off the shelf thing.

totally irrelevent


Dave

 

[GreenGiant]

OK Im going to put this in bold red cuz its just too important to ignore

You are obviously unaware of safety procedures when working on electrically powered equip

There are things called isolation/lockout tags. These are used BY THE PERSON doing the repair/maintenance work on the gear
ONLY that person has the power to remove the tag from the disabled power circuit

Power CANNOT be restored to the equip UNTIL the person who placed the isolation tag removes said tag

This is to stop other people restoring power. There are huge penalties for anyone removing lockout tags that they didn't place. These and related issues are usually always discussed in company safety meetings to make sure ALL staff are aware of the consequences



totally irrelevent


Dave

See at my work our LOTO is the service mode key, BUT the placement of the safety box (only place it can go) is out of sight of the control PC, and if the person trying to run it doesnt look at the camera's and happens to tell the system to move when the service person it pressing the liveman switch (again another "what-if" which is completely unlikely and will most assuredly never happen) then the service person could get hurt. Also onto the what-ifs again, what if the LOTO tags just randomly fails? double redundant system? What if they both fail? so on and so forth.

We use a live man switch that is Off-On-Off so if you press it too hard it shuts off again, from a what-if scenario if they land on top of it just right as to not push it too far, even if the person is unconscious, they could cause motion.

I understand the need for safety, I really do, but you can't plan off of what-ifs, some yes, but like I said you will just end up wasting time....
What if a plane carrying a huge pallet of something heavy is flying over and the restraints ALL happen to fail, and the plane moves in such a way that causes it to fall out, after which it clips a car just so that it swerves and flips 5 times careening into 3 other cars which hit a couple telephone poles breaking them making them fall into the side of the building you work at breaking through a large window showering glass all over the place which cuts a high pressure hydraulic line spilling the fluid all over the place causing a coworker to slip while carrying a heavy box, which falls onto a table in just a way that it causes a tool to go flying through the air so it hits the shelf on which you store some heavy equipment and dislodges it so that the whole shelf drops its contents onto a grinder and happens to hit the switch to turn it on causing one piece of metal to fly across the room striking you in the chest.

These are the what-ifs I hate... I mean they are endless, but you have to stop somewhere.

Also it is not totally irrelevant, if he designed and built it he has to take the blame if safeties fail, also there is no mention of what the thing is he is trying to turn on is, he could want a fan to come on and that's it. I wouldn't install a system like that in anything that would move or cause harm to someone, ever, I'm not stupid. But when I am testing I will defeat safeties to see how the system responds, but never in the field.

Also look at my signature, I was merely answering the question, not suggesting to do it or not to do it, like I said, in an industrial system if there is a chance to injure/kill someone I would not recommend doing it.

 

[davenn]

I understand the need for safety, I really do, but you can't plan off of what-ifs, some yes, but like I said you will just end up wasting time....

You obviously still dont

SAFETY of workers is NEVER a waste of time. It is the #1 consideration NOTHING else is more important

Also it is not totally irrelevant, if he designed and built it he has to take the blame if safeties fail,

so you dont care if he has the death of a workmate on his consious for the rest of his life
as he sits in jail for manslaughter ??

all I can say is I hope never to work where you do or under a manager with your concepts of worker safety .... its a nitemare and a death waiting to happen



Sorry to sound so harsh mate, but you really do need to understand the importance of this!

Dave

 

[GreenGiant]

You obviously still dont

SAFETY of workers is NEVER a waste of time. It is the #1 consideration NOTHING else is more important



so you dont care if he has the death of a workmate on his consious for the rest of his life
as he sits in jail for manslaughter ??

all I can say is I hope never to work where you do or under a manager with your concepts of worker safety .... its a nitemare and a death waiting to happen



Sorry to sound so harsh mate, but you really do need to understand the importance of this!

Dave

Look at the examples I was giving, to be perfectly honest the safety measures we have here where I work are not enough in my opinion, but it is safe enough that no one will die. Im just saying there is a point at which the what-ifs become stupid. You need to find that line, you could sit around arguing what-ifs about one system until the sun goes out, you have to stop it before it reaches the realm of idiocy. My example of a guy falling unconscious in our system and falling just so that the live man button is pressed between 5-10mm exactly not any more, not any less, is the realm of idiocy.

I said that in haste, I would never condemn someone to that, I was imagining a situation where it was nothing serious. Yes he should plan ahead for safety, and safety is in the top 3 things of consideration (referencing Dirty Jobs there, but he says it honestly with reason and I'm not defending that).



I know you are just being overly enthusiastic about this for the sake of the forum, but honestly, I am all about safety on the job, nothing where I work, that I do, is unsafe beyond acceptable limits (meaning maybe pinching a finger, or pulling a muscle trying to reach something in an awkward spot)

I am not reading this thread anymore so you really can stop replying to my posts... thanks.

 

[davenn]

I know you are just being overly enthusiastic about this for the sake of the forum

no not just for the forum ... over the years in various workplaces including my current one, safety is drummed into us continuously. Every month our company runs a safety meeting where any arising issues are discussed and remedied, be they in the office, workshop areas or out on the field sites.

SAFETY is the #1 consideration, NOTHING else is more important

that is part of what I wrote above and that ^^ is close to word for word what is on huge signs around our workplace.

our field techs have to do a take 5 report for every job on site before they start
Take5 = take 5 minutes to complete look over the worksite, make notes in the Take5 booklet noting any possible hazzards etc. And if anything significant is found, work doesnt start till the hazzard is removed ... no matter how long that takes to do.
Work DOES NOT start too its safe to do so

Dave

 

[KrisBlueNZ]

GreenGiant, I think you need to reconsider your attitude to safety. Where there is a risk of injury or death, one should simply banish any thoughts along the lines of "that couldn't happen", any attempt to justify one's failure to consider any particular possibility, and any sense that the job of maximising safety has been (or can ever be) achieved. Instead, research, experience, thoroughness, thoughtfulness, and imagination are needed, in order to minimise risks.

I know this, and I have very little relevant experience. shrtrnd and davenn obviously have a lot more, and if I was in your position, I would (a) stop trying to justify my naiveté, and (b) shut up, listen carefully, and think hard. "The life you save could be your own"

 

[oliver]

Hello Again KrisBlueNZ

I did not follow all the discussion on safety so wont comment, but here is what I have found.

I rigged a delay on pulse start and a Delay on timer together with a siren ( PCM-01 AND DAP1) .

http://www.myvirtualpaper.com/doc/a...ferrer=http://www.acdc.co.za/cattypenew.php#4

http://www.myvirtualpaper.com/doc/a...errer=http://www.acdc.co.za/cattypenew.php#14

It works great but there is a flaw. when power is applied the pulse start and delay on timer has a 1 second pulse before it goes through its motions.

that means that the machine will start even before the timers start there cycle
no good for safety.

really need some help here


Oliver

 

[KrisBlueNZ]

Sorry Oliver, I don't want to get involved. You should be able to guess why.

If you really didn't follow the discussion on safety, I think you should!

 

[jcurrie]

without getting into the ongoung argument about safety the mine i wouked at had auto restarts on the belt lines but there were all kinds of safety devicies on them , the belts had to start in sequence(you can guess why) the out side started first them about three min later the next belt was on but before it started there was a becon and a klaxton at the drive they sounded for 1 min then the entire belt line was lighted the lights were flashed of and on three times before belt started, there was also a pull cord on the entire belt that killed the drive power, which were to be puller if anyoue was working on belt even if you had shut off the power to the drive , point being if auto equipment is used you need more than one safety lockout, the only true auto start up was the ventlation fans if power failed as soon as power was restored the fans would come back on after asveral warning devices were actavated, but the fan housing only had one access door that had a safety cut out the mine side was blocked by a heavy screen.so if auto start is used you need several failsafe devices

jc

 

[davenn]

thread closed