electromagnets of deduction

[Andrea O]

Good morning, everyone!
for a degree thesis I am following a project in which, for safety reasons, it is necessary to install an electromagnet that, in case of anomaly ( lack of current/tension), must be able to release a system of levers that guarantee the implementation of a safety condition.
the real question I wanted to ask you is as follows: in case I used an electromagnet that without power keeps me the system blocked (as a permanent magnet) and that instead powered releases the system (disactivation of the magnetic field), there is a system (electrical or electronic) that is able at the time when I have the battery pack to provide me a minimum current (also residual, minimal) able to disable the electromagnet and activate the safety system?
Thank you in advance.

 

[MassiVonWeizen]

search for inductive endings. for example baluff, omron, sick....

in certain applications are used both mechanical and magnetic ends

 

[Andrea O]

search for inductive endings. for example baluff, omron, sick....

in certain applications are used both mechanical and magnetic ends

correct me if I'm wrong, but aren't these sensors just able to detect a position?

 

[exxon]

you need a temporary power source.

due to the energy required, these sources can be (in order of increasing energy)
- non-polarized capacitors
- electrolytic capacitors
- supercap (type of electrolytic capacitors)
- rechargeable batteries

you should consider well the choice you have in mind, because not as reliable and not always acceptable from the regulatory point of view.

 

[Andrea O]

you need a temporary power source.

due to the energy required, these sources can be (in order of increasing energy)
- non-polarized capacitors
- electrolytic capacitors
- supercap (type of electrolytic capacitors)
- rechargeable batteries

you should consider well the choice you have in mind, because not as reliable and not always acceptable from the regulatory point of view.

for the application it is necessary a safety element that either an electromagnet or a solenoid. for the electromagnets I had thought of this configuration, therefore avoiding the constantly powered seal electromagnets, for problems of absorption and overheating.
Do you think there might be alternative solutions? I have seen that the capacitors, for the field of application in which I have to go to act, are generally avoided.

 

[meccanicamg]

the only system is the permanent magnet with mechanical lever drive. to understand it is a disc with many sectors of calamity oriented. There's another set of magnets in the middle. There is a lever mechanism that removes or sums the magnetic field.are the traditional equipment of small and economic rectifications like lapidelli.

you would need to electromechanize the knob with an electric actuator plus a spring, so that it is monostable.

You're the one allego a catalog with many solutions.
contact the company as well and you will see that a solution find it....maybe a customized magnet.

 

[francescodue]

I would like to point out a detail: we are talking about safety condition following anomaly.
in practice while the system is in operation the lock levers remain firm; in case of failure these are free to act.
the initial idea is that the system is normally blocked, in case of failure it is activated to unlock.
seems to me a little sensible: over time many things can happen that prevent activation; also only the oxygen of contacts.
It seems to me that in the alarms we use closed contacts, with current circulation in the perimeter, precisely to avoid this risk.

 

[exxon]

for the application it is necessary a safety element that either an electromagnet or a solenoid.

It is a sensible request: they are systems that guarantee security just because they release the movement only when they are powered. servomotor brakes work just like this, what you are asked is to implement a similar security level.

for the electromagnets I had thought of this configuration, therefore avoiding the constantly powered seal electromagnets, for problems of absorption and overheating.

As I told you, the first verification is to see if such a system is accepted or not. I personally believe it with a lower degree of security than that with the solenoid fed in the active phase.

the problem of overheating is there, and it is known. in the servomotors I mentioned before, sometimes the heating given by the brake solenoid is higher than that of the engine itself. is the price to pay for intrinsic security that offers this type of solution.

Do you think there might be alternative solutions? I have seen that the capacitors, for the field of application in which I have to go to act, are generally avoided.

to accumulate energy, the systems are those (if we don't go looking for destroyed solutions like fuel cells or other solutions outside the common world). as I told you, it is not a solution that I like and that I would only use if forced (and I would not go to sleep quietly).

If the problem of energy consumption and overheating is of primary importance, one can act on the mechanical side. you use a smaller solenoid and then with a snap and rearmament system you manage the part that requires greater forces (similar to stecher and trigger in firearms). These systems are used in large power safety switches. In fact, these systems also reduce safety, introducing mechanical parts that could fail in their action, but if well designed is a sufficiently reliable system.

 

[welcome to the machine]

in fact the hypothesis of post 7 is not in norm.
the system, if it has to be a security system, must act in the absence of current so the problem of keeping the magnets activated permanently cannot avoid it. At best you can try to make a mechanically almost monostable system, but you can't rely on buffer batteries, capacitors or anything. not because they would not be reliable, indeed, but only because the norm prescribes that the system is active, or rather disactive, without energy. any device that you attach this aspect could surely work (a condenser is very reliable) but those who adopt it should certify that it corresponds to the norm, and it is not a simple job. If this device is not the key point of the project, I suggest you put a good electromagnet always activated, with its manufacturer certification and maybe insert it into a check system that redundantly controls its positions, activation and deactivation and what else.

 

[welcome to the machine]

I had not read the answers of my friend exxon, who I find with pleasure. as often happens what I presume finds confirmation in what he explains much better than me.

 

[Fulvio Romano]

Hi.
Let's look at your question better. to say that a system is or is not "standard" does not mean anything if we do not understand what norm it is. What world are you talking about? Machine directive? standard toys? Building? nautical? each area has a different approach to security with specific regulations.

for safety reasons, it is necessary to install an electromagnet that, in case of anomaly (the lack of current/tension), must be able to release a system of levers that guarantee the implementation of a safety condition.

explains this concept better. a condition is not implemented. at most you are located or you can carry in a condition.
Moreover the fact that in case of anomaly a system does something active to carry out in a safety condition is a method deprecated by many norms. Can you come down in more detail?

in case I used an electromagnet that without power keeps me the system blocked (as a permanent magnet) and that instead powered releases the system (disactivation of the magnetic field), there is a system (electrical or electronic) that is able at the time when I have the battery pack to provide me a minimum current (also residual, minimal) able to disable the electromagnet and activate the safety system?

There are several ways, but if I can afford, those listed in the answers above I do not like. what proposes mechanicalmg can work, but it is not a safety device. the technique proposed by exxon exists, it is used and responds adequately to your question. but in my personal opinion he answers a wrong question.

a permanent magnet can have a winding that if fed neutralizes the magnetic field. If you cut the energy you have an active magnetic field without the need for accumulators.

a selectable mechanical system can be activated and deactivated by electromagnets without the safety condition needing energy storage.

a single-stable system inserted by a spring and disengaged by an electromagnet stores mechanical energy (molla) instead of electric. It is useless to say that in order to say one to the uni en iso 13849/2 we like more springs than the accumulators.

but the real question is, if you realize a security component, then can you use it? the rules they say?

 

[welcome to the machine]

that you are not talking about toys or nautical seemed obvious to me, but I would still like to understand if the security system of which the op speaks, where to protect the machinery (e.g. to stop an uncontrolled inertia that could damage it) or should protect the operator? between the two cases there is a huge difference.
I have assumed that the operator's safety was concerned, so I control the accesses after the destruction of the residual energies of the machinery. if we talk about this, below some of my evaluation.
If we speak instead of the first case, to express oneself it would be necessary a greater knowledge of the system of which, rather abstract, we speak. As a result, what I wrote below... has nothing to do with it.

l'op in post 7 wrote " the system is normally blocked, in case of failure it is activated to unlock. " no system (of levers, in this case) that must Attivarsi in case di fault It's normal. there is a contradiction in terms between the failure of a system and the activation of a part of it. unacceptable contradiction in the field of safety regulations on an industrial machinery.
"a selectable mechanical system can be activated and disabled by electromagnets without the safety condition needing energy storage. " What does that mean? If you check, ,p.e., a door, in case of failure would remain stable closed because the electorate will not have the energy to switch from the stable position of closed to the open one? so the system is safe, but does not meet the obvious need to be able to access the machine without having to reactivate, at least, the power to the electromagnet. If it were instead an internal block of the machine (e.g. an ancient system or blocking a part in rotation), it would be admissible that it cannot be restored and therefore make the machine free again, if not when it can be fed again.

a condition really allowed and practicable, is that the system has preliminarly accumulated an energy that, released in case of failure, safely put the system, eliminating, not mitigating, the risk that any residual energies of the machinery can cause damage to the operator.

the activation of the system which releases the energy necessary to release the security system in turn, must take place through certified methodologies.

In fact, the problem is not the purely technical aspect of the system, but la certificazione of the same. Who does it? risk analysis, calculations, test methodologies, validation of prototypes through documented tests etc. etc. ... never come out if it's not your job.

But, I repeat, all this makes sense only if we talk about operator safety, so referring to the infamous machine directive. if you just want to prevent a machine from running away when the current is missing, so long as this does not cause any risk to the operator you can do as you like, following the advice of more qualified friends who intervene in this community.

 

[francescodue]

@ welcome to the machine.
I'm sorry my intervention wasn't clear.
in post #7 I wrote what I understood about the initial request.
In fact in the next line I wrote that it seemed unsatisfied (unusing to put a device that activates a safety unlock in case of failure.
regardless of certification it seems to me that you must always prefer a solution "to fault test": in the sense that it is preferable a false activation rather than a failure, always in the interest to protect the operator.
the problem of absorption (and therefore of overheating) could be overcome by carefully studying the mechanical system that is released. appropriately studied can suffice a minimum force to keep it "in pause": Perhaps it is enough to block a single element that, when freeing, lets move everything else by pure gravity. (of course this is just an idea; who knows more can give the best suggestions.

 

[exxon]

As you have been asked, it would be better to specify whether the whole is subject to a particular directive (such as the machine directive) or whether it should be built in accordance with specific product standards.

another point on which you have to be careful is that one thing is to prevent the start of the machine, when the kinetic energy is still nothing, but something quite different is to stop a machine already started, when the moving organs can have accumulated a very intense energy that, willing or harmful, it is necessary to dissipate, or to transfer, to be able to stop it.

 

[welcome to the machine]

There's nothing you need to be sorry about. We'd miss it. I'm the one who messed up because I confused you with the op...
I wanted to understand if we were talking about security for the organs of the machine or .. for the operators!.
What you write is technically shared, but I don't think we can ignore the certification, unless it is an academic exercise or a prototype that cannot be conducted except by those who take responsibility and not in an industrial environment.
I do not know what the machine does and who should use it, but in Europe it takes certification, or even self-certification, and it must be done according to the norms. Even so, in the event of an accident, it is the objective responsibility of the builder and all the documentation that led you to declare that what you have done is in accordance with the norms, you must bring it to the judge within 24 h.... and the company administrator is responsible penally, even if he does not know that it is an electromagnet and thinks that inertia is a kind of salad.
but if I read my posts calmly, distinguishing you from gorea0, maybe I make less mess.....

 

[Fulvio Romano]

that you are not talking about toys or nauticals seemed obvious to me

You're obviously smarter than me. to me still now is not evident at all. and I would like the op, if he's reading, to try to clarify the situation better.

no system (of levers, in this case) that must Attivarsi in case di fault è the standard

some examples of type c rules that prescribe systems that should be activated in case of failure (or accident) for the protection of persons:
- the insertion of moderation bars into a nuclear reactor in the event of a process escape (nuclear/reactor)
- the safety evacuation of a paniera in case of overflow of the ingot (continuous/breakfast)
- the safety rotation of the turntable in case of failure to the drawer (continuous/cold)
- scrap shears in case of incarceration (desurg/laminator)

are dozens (centinaia in the case of the turret) of sensors and actuators who begin to work when igniting the emergency fungus.

a selectable mechanical system can be activated and deactivated by electromagnets without the safety condition needing energy storage. What does that mean? If you check, ,p.e., a door, in case of failure would remain stable closed because the electorate will not have the energy to switch from the stable position of closed to the open one? so the system is safe, but does not meet the obvious need to be able to access the machine without having to reactivate, at least, the power to the electromagnet. If it were instead an internal block of the machine (e.g. an ancient system or blocking a part in rotation), it would be admissible that it cannot be restored and therefore make the machine free again, if not when it can be fed again.

Why? a non-powered bistable system remains in place, but this does not mean that a mechanical lever cannot allow manual unlocking.
An example? a trivial safety electrosting. It's monostable normally closed but the concept is the same. if powered is unlocked; if disused and closed, it is blocked. However, it has the escaped lever so if one remains locked inside can go out and in doing so it also blocks the machine.

 

[welcome to the machine]

I'm sorry but you wrote "a selectable mechanical system can be activated and disabled by electromagnets without the safety condition need energy storage "I don't understand the mechanical lever now. . .

 

[welcome to the machine]

However compared to the other points you explained to me in the #16, thank you, I wasn't aware of it. They are very far from the type of machines I take care of and I obviously had a limited vision.

I'm convinced that the type of car he's talking about goes0 is not adhering to the cases you mentioned, but it's just my impression, not because he thinks I'm more or less awake than you. maybe overestimated who deals with the "'insertion of moderation rods in a nuclear reactor in case of process escape' . I strongly hope that you will not come to look for solutions in a forum.... But you never know. If so, I entrust it to your competence.

nb: the first two rows are absolutely sincere. from "I'm convinced ..etc" instead, I'm kidding. That is why I have been given the opportunity to express my views on this subject.

 

[Fulvio Romano]

I'm sorry but you wrote "a selectable mechanical system can be activated and disabled by electromagnets without the safety condition need energy storage "I don't understand the mechanical lever now. . .

are two different safety functions (ref. uni en iso 13849-1) present on the same component.
a selectable mechanical system can be "activated" with an impulse and "disactivated" with another pulse. when it is activated however it does not need energy to keep it active. This is the first function.
At this point, however, the fact that a security function is inserted mitigates a risk (e.g. an operator cannot enter and get hurt), but could generate another (an operator who is inside remains trapped). a second security function is inserted to remedy this condition, for example a lever accessible only from the inside that can "disable" the locking system.
I don't know if I've been clear enough.
below find an example. I repeat, however, the safety electrosting is not bistable.

I'm convinced that the type of car he's talking about goes0 is not adhering to the cases you mentioned, but it's just my impression, not because he thinks I'm more or less awake than you. maybe overestimated who deals with the "'insertion of moderation rods in a nuclear reactor in case of process escape' . I strongly hope that you will not come to look for solutions in a forum.... But you never know. If so, I entrust it to your competence.

He's doing a project for the thesis. Do you see it so unlikely that the professor gave him to solve the scenario of three mile island and he is trying to make it enveloping electric wire on a piece of metal?
We've seen worse on these pages.

 

[francescodue]

I was convinced otherwise about nuclear reactors.
That is, in money, that the security system kept on bars until everything is okay; but in case of failure those fall alone.
In other words, the safety system is always active, but is hindered by the proper operation of the system.