Actual Elevator Question

[bamatki]

I have searched but did not find anything on this question.

Do they actually use PLC's for elevator control or do they use some sort of other related device ?

I was on an elevator this weekend and although the button for floor two was pressed once and lit, someone began to press it again, I said that I didn't think that it would make the elevator go to floor two any quicker, "pressing it again and again to make the doors close faster". They informed me that oh yes there were certain elevator controls which responded to the number of times that a particular floor number "input" was pressed.

It just doesn't seem to be right somehow, once an input is pressed and confirmed with a light, that should be it.

 

[Angus]

Ive used Mitsubishi and Omron plc's on elevators.
I do know that some elevators are pc controlled but this is not the prefered route

 

[TimothyMoulder]

Elevmike is best qualified to answer this one, but I always thought they were based on the current floor and the direction requested, ie if you are on floor 5, get on a down-bound elevator, and press 2 and 4, it will go to 4 and 2, in that order. If somebody on 3 is pressing the down call, it will stop there to get them as well, 4,3,2.

If the guy who gets on at 3 starts pumping the 6 button, he gets to hang out until the elevator reaches 2 (maybe even 1, if somebody has a call in to there). Any number of presses he wants to make to make himself feel better is irrelevant to what the elevator will do.

At least, that's my understanding. How about it Mike, do I get an "A"?
TM

 

[Fritz_frederix]

Hello,

I've been asked by a friend to help building an elevator in his house. It's an 1 floor elevator. Does anyone has an elektrical drawing of such an elevator?
I just need it to see what kind of security controls are implemented. I will write the plc program by myself.
Also a guide of the strenght of the motor & reductor would be nice (4 person elevator) would be nice.

Rudi

 

[elevmike]

Yes PLCs are used on many elevators. I would guestimate that about 1/3 of all new elevator controls installed are PLC based. More educated owners are spec-ing PLCs to avoid getting stuck with propriatory equipment that will be obsoleted in a few years, and are gennerally less robust then PLCs.

In reguards to pushing the button; just once will do it. Once the button is lit, it wont help pushing it again. The reason is obivious. All it would take would be one idiot to screw up the entire dispacth.

 

[Rick Densing]

Hello,

It's an 1 floor elevator. Rudi

Should be easy. I would expect it gets more difficult when you try for 2.

 

[Fritz_frederix]

Rick,

I shouldn't be that hard but I'm just looking for some guidelines. Such as there are - elektical brake on the reductors side. - Doubbel low level switches - double high level switches but what are the other security controls necessary?

Rudi

 

[elevmike]

Rudi,

If it's a short elevator (two floors), I would suggest going with a hydraulic unit. Much easer to install. Additionally for safety's sake get a copy of the local elevator code BEFORE you and your friend start doing anything. Elevators are a lot more complex then you might initatially realize.

If you post more details about the configuration, I might be able to steer you some.

 

[Rod]

Isn't a one floor elevator called a closet?

Sorry, I couldn't resist.

Rod

 

[Rick Densing]

Isn't a one floor elevator called a closet?

Maybe it is this one. I know there is a vid on the net somewhere.

 

[CaseyK]

I do know that some elevators are pc controlled but this is not the prefered route

Seems like a whole new meaning to the blue screen of death...

regards.....casey

 

[jolio ST]

Hmmmmm.....

Interesting topic. I do have some questions on it though. I tried to reason it out myself but I do not believe what I theorized.

The apartment where I stayed just had the lifts upgraded after almost 15 years in service. The new ones are faster, and able to carry a heavier load. It travels from the ground level to the 14th storey. I once tried to press every level starting from the 2nd onwards, but it just resets itself after i pressed the 12th level.(Don't ask me why, just my itchy hands trying to have fun)
I thought maybe it's because it has calculated a sum showing the number of people in the lift exceeded the maximum number allowable. But I'm only one person, and the calculated mass compared to the total mass is only a fraction.
So is it right to say the piority is set first for maximum number of passenger allowable, and disregard the total calculated weight?

Another question: the old lifts only travels between ground level, 5th level, 10th level, and the top floor. so it makes only 4 selection buttons. If a mistake was made while selection of any 2 levels for example, I am able to reset the selection by pressing all the 4 buttons. but it will travel to the nearest selected level to allow people to leave (in this case, open for airing only). I wonder why.

My last question is: If elevators nowadays are PLC-based, what aboutt olden elevators? The ones where there is a lever and doors you have to open them yourself.

I'm just curious, and I'm glad I did not damage the lift in anyway.

regards
Sherine T.

 

[elevmike]

Casey,

PLCs are very safe in elevators. The code (AMSE A17.1) provides for strict guidlines regarding controller design. Even if the PLC wanted to run in an unsafe manner, the hardwire circuit would prevent it.

Sherine,

What you expireanced was the anti-nusiance feature. The elevator could be counting passengers as they walked through the door, or weighing the load. If the amount of calls exceed what would normally be expected, all the calls are canceled. This is very common.

Older elevator are/were all hardwire relays, counters & timers. The PLC just replaces the logic of the hardwire relays. When I did my first PLC elevator, I simply copied the hardwire drawing into my ladder logic.

 

[Rod]

Mike,
I'm curious as to the average amount of IO in, say, a 4 level cable lift.

And do they actually measure mass?

When six 3 foot wide people step on and I see the car floor lower than the door sill - I be heading for the stairs!

Rod

 

[wildswing]

...They informed me that oh yes there were certain elevator controls which responded to the number of times that a particular floor number "input" was pressed.

Oh yes, it's absolutely true! There's even a word for it...

Elecelleration: The mistaken belief that repeatedly pressing the elevator button will make it go faster

More HERE