Elevator (passenger lift) call collective.

Discussion in 'The Projects Forum' started by Jeffnars, Sep 9, 2012.

  1. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    Hello guys. I'm about to start a project to build a duplicate mini of a passenger lift. Just a model to sit in our office.

    The project will consist of a Motor for drive, Floor positioning selector (micro switches) I'll be using 24v dc power supply.

    At this stage there will be no doors. I will add that into the circuit diagram at a later date.

    Ideally I would like to keep it based on relays. I'm open to a logic setup but it's been a while since I've touched logic circuits. Even if I get a complete logic on a diagram it would be hard for me to translate it into the real thing.

    I don't want to use a stepper motor as this is not how a conventional lift works.

    I understand the basics of a lift as I'm a lift engineer. Getting diagrams will not be a problem. However a call collective lift is difficult to come across.

    Call collective as in u can press floors 1 and 2 and it will collect the calls and the lift will stop. Wait, then travel to the next stop.

    I've searched the forum and there's not a lot on here. Yes there's a lot of posts but nothing complete.

    Any comments welcome.
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    this would be easy to accomplish with a microcontroller..... but using basic switch and relay logic may get very confusing!

    But still do-able.....

    Maybe if you had some sort of sensor (IR sensor would work) on the lift itself, and have an IR emitter located on each "floor".... as the lift comes near the floor it will either detect a "Stop" or "Don't stop" signal...... as the user presses the call button on that floor, it will latch a relay to turn on the IR LED (Emitter) for that floor, and also send a "Run" signal to the main lift drive.... of course there would have to be some sort of circuit to delay the lift on each floor for a determined amount of time, you probably don't want it to stop briefly and keep going :)...
     
  3. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    The only thing with a micro processor is I don't know anything about programming them. How much would a basic one cost for this project??

    I was hoping to keep the positioning to limit switches and cams. This is how thy work on an older relay lift.

    My boss worked on lift from the 60's and he assures me I can build a relay based controller. Like you said it may get complicated but I'll cad design it all first :)
     
  4. BMorse

    Senior Member

    Sep 26, 2009
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    How many floors do you have to include in the model?

    It is do-able with relays and switches, but the control panel may end up bigger than the model :).
     
    absf likes this.
  5. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    Yes my only concern was the size of the panel in comparison to the model.

    Ive had a quick look at programming pics but still don't understand how I can implement it into a circuit for a lift. I'm only used to relays.

    I would like a 3 floor lift. Each floor to have one call button. The lift car for the moment doent need to have buttons.

    24v motorat full speed. Then I'll regulate the speed to get a levelling speed into the floor.

    The more I add the more I'm looking im looking into a micro processor. :s
     
  6. BMorse

    Senior Member

    Sep 26, 2009
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    3 floors won't be too bad for relay logic..... I was figuring it was a skyscraper :)

    and if you used PCB mounted relays, they could be small and compact enough not to take up too much time..... The one thing I can't get my mind around right now is how to delay the lift on a floor until it moves to the next one, with just a standard relay without using any IC's or 555 timers.... possibly a delay on make relay???
     
  7. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    Ok 555 timers I can handle.

    I can't handle anything I have to program. At least with a 555 timer I can use it in my cad software.

    I can design a simple 2 floor up down stop no problem.

    Even a two floor two speed lift would be acceptable. Just something harder then a 2 floor up down stop.

    Here in the uk we don't generally have multistory lifts
     
  8. absf

    Senior Member

    Dec 29, 2010
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    I'd really like to see how does a lift control circuit using relays look like. I've been working in an Ericsson telephone ARF Exchange using thousands of relays. These relays are mostly multi-contacts and the armatures are adjustable with special tools.

    Can the lift control model use the commercially available Omron relays which has only 2 or 3 sets of change-over contacts? And how does the schematics look like for a lift controller? Would you be using 12V for the relays and 24V for the motor?

    Allen
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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    absf likes this.
  10. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    On lifts we use 14pin plug in relays.

    Before that it was the older, larger relays with arc shields.

    My boss told me of a building which had 4 lifts running full collective calls. There was 8 controllers all full of relays. He said you couldn't hear the person next to you. No mobile phones to call for a technican if there was a fault. Younjustbhad to fix it all your self. Because health and safety wasn't an issue back then. They used to use 2 wires and a light bulb for a meter. And if the light didn't light up then they would unscrew the bulb and place a penny in the hole and short out that part of the circuit to see if they had a poor contact.

    Nowa days it just read what the processor tells you and go to the fault. Ok some off the lifts arent that great at telling you where the faults are but it's nothing like the good old days where the control panels would like twice the age of these new processor panels.

    I'll have a read on that today Bmorse. I'm in the uk :)

    Thank you
     
  11. absf

    Senior Member

    Dec 29, 2010
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    That very much describes what I am doing nowadays in an Ericsson AXE computer Exchange. The alarm panel will tell us that there is a fault. We then use a PC terminal to diagnose the fault, the result would indicate the "suite", "rack", "magazine", "card" position of the faulty card to be changed. With a command, we can just make the card "out of service", and replace the card with a spare.

    Of course, if the fault falls on the CP, that would be different story. We would have to come back after midnight to clear the fault when the traffic is low.

    Allen
     
  12. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    Oh for a power supply. Can I just use an old 24v laptop power supply??
     
  13. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    If I started to look into the micro processor route what chip would I use?? Does it just use logic to work out the input and output?? Thank you.
     
  14. williamj

    Active Member

    Sep 3, 2009
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    Jeffnars,

    I'm not familiar with "collective call" but I was thinking a latching relay circuit between the call button and the call circuit that could be broken by a limit switch at floor level when the elevator arrived.

    Don't have time right now but will work on something later if you still neeed it.

    williamj
     
  15. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    That would be nice how ever I'm also interested in designing it myself. Yes latch relays are going to solve the problem where I cannot keep the calls active while the lift serves different floors whilst retaining a call. For many of reasons the lift will not move away from floors if the doors are open beause the saftey circuit will maybe have a relay at the end which will stop any forward circuit to the directional relays.

    Hopefully u guys understand I want to keep everything lift related. If it's a relay controller I would like limit switches at micro switches. If I went processor is have optical switches to stop the lift. Optical switches were not readily available when relay controllers where about. Instead as the lift passes the floors it would send a pulse to a selector which turned and made different positions in the controller to replicate what it was doing in the lift shaft/hoist way. :)
     
  16. NFA Fabrication

    Member

    Aug 12, 2012
    104
    3
    Does this have to be replicated as a full size at some point? One thing I have been doing to control things along these lines is to disassemble RC servo's, take out the gears, solder two wires onto the motor connections from the board (Take the motor itself out ideally, but not needed). Now you can add an external motor, and drive it from those wires (Or use those wires to control relays if the motor draws too many amps for the servo's board). And then add a long arm to the original servo output the makes a full sweep with your elevator from top floor to bottom floor. Now you essentially have an elevator that can be controlled with a basic servo controller (Maybe 3 555 timers set up for the 3 ms pulses needed for each floor?) through the servo's original input lead. That may sound more complicated than it actually is. It is not a complete solution for your entire project, but I think it is where I would start to get the motor/level system basically in place.
     
  17. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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  18. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    I got a chance to revisit a site which has a 4 storey call collective full relay based controller. Take it from me. I can see why it hasn't been covered.

    I'm going to lower my ambitions a little.

    I would like to now do a up Single call collective. On a two storey lift. With two speeds. Like the one in the above video.

    Suggestions welcome.
     
  19. DMahalko

    Senior Member

    Oct 5, 2008
    175
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    I am not familiar with what a call collective is, but in general I know elevators tend to keep moving up or down from floor to floor until all calls are handled in one direction or the other.

    • Keep going up until all those are handled. Switch to "down" mode.
    • Keep going down until all those are handled. Switch to "up" mode.
    • No calls active.


    The most direct mechanical route would be a rotary selector switch with step advance/reverse solenoids. (As a young child someone gave me some 1950's avionics with these inside which I disassembled to figure out how it worked.)

    If you have ten floors then you have a 10 pole rotary switch and 10 call relays, with ratcheting rotary solenoids on both ends of the rotary switch.

    • To rotate the switch forward, you send a pulse to the ratcheting solenoid on one end.
    • To rotate the switch backward, send pulse to the other ratcheting solenoid on the other end.


    The call relay for each floor has a couple of switch poles:

    • Self-hold, keep the relay coil powered when triggered by user, has another N/C relay in this self-hold loop so the control can disconnect the call relay when servicing is done
    • Call active, output tied common with all other call relays, tells the controller to keep running until all calls are completed
    • Floor active, single output to one of the ten rotary selector switch poles


    To set direction of travel you have an "Up/down relay group" of two relays, if both relays are off then no direction specified. If one turns on it locks out power to the other relay until the controller direction is reversed.

    The name for this two-relay group would be a "flip-flop".

    Initially figuring out which direction to go from the current position can be handled by additional contact rings on the rotary switch, and using a bridging contact ring that joins floor poles together when the rotary switch moves:

    Current rotary position is #4

    • Contact 1, 2, 3 connected together - the "down" initiator
    • Contact 5, 6, 7, 8, 9, 10 connected together - the "up" initiator
    A call comes in on #8 call relay, that is UP direction relative to current rotary position, so UP relay is triggered and held on by the common "call active" from the call relay.

    If a call is already active and a direction is already selected, input from these rings are ignored if more call relays are activated.



    The rotary stepper steps rotary switch forward, checking for active calls in the selected direction. When the rotary end-stop is reached, if calls are still active, then the servicing direction is reversed and the rotary stepper now moves back the other way.

    When all calls are handled, then all call relays are turned off, and the direction selection relays also turn off.



    While it is probably possible to do this with all relays, it is way more complicated to wire. Though I suppose the idea there might be to eliminate parts. If you can "virtualize" a rotary stepper as a group of relays, that's one less complex part you have to stock.
     
    Last edited: Sep 11, 2012
  20. Jeffnars

    Thread Starter New Member

    Sep 9, 2012
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    That's exactly what they used on lifts from the 60' 70' and 80's. My only problem is finding out what they are called in the uk and buying one. It's to precise for me to build with tensiion springs pulling the arms that move the stepper back and forth.

    In the lift industry we call them Floor Level Selectors.

    Hummm. I'm now going to browse the Internet. ;)
     
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