A great video that can be understood by the layman. They would have saved a fortune if dual coil flip flop relays existed back then. You have a good method of explaining simple logic circuits.
harleybadger1 Thanks for your comment. This video is one of my favourite video tutorials because I took my time and it took 3 months to complete (in my spare time). So it was only uploaded when I was happy with everything. I love trying to explaining things from a beginner's point of view and glad you enjoyed it. Did you see this one yet...THE MASSIVELY INFORMATIVE LIFT/ELEVATOR VIDEO (p1)
mrmattandmrchay I just watched both parts, and I can say very well done indeed. The Allen-Bradley controller is familiar to me, I have seen it used in other scenarios here in the US. Your video editing, as well as your always-informative animation, make it very easy to understand.
Thank you SO much, I have one of these old Otis lifts on my maintenance route and you just answered more questions then I even thought of. Very clear and easy to understand with your visuals. Thank you!!!
no problems, glad you found it interesting. It's worth pointing out that this is just to give people an idea of how it works. The ACTUAL carriage can have loads more contacts on it - seperate ones for UHS, DHS (up hall stop, down hall stop) and so on. watch?v=Bc2F9DfDAiQ @6:40. Also see watch?v=wbvIXYZDdlI as I've labelled the contacts at @5:48. Thanks.
+titony54 Hi! I'm not actually a lift engineer but Ive had a life long interest in them and I know a few people from within the industry, mainly through youtube. It really Facinates me how people designed these systems from prototypes to working models that have stood the test of time. My career is electronic security so we do work with lift engineers from time to time with CCTV and Lift Access Control. At my company if you want to do something with a relay, I'm your man! Love messing around with relays timers and circuits. I have several elevator parts including selectors that I may connect up sometime but it's difficult finding the time. Thanks for your comment
this was my simplistic description, it's actually FAR more complicated as there are more brushes and contacts on the real device. + all those relays!!! :)
11:54 _"If the lift is not at a floor, the contacts join together"_ In case i press the stop button between floors - Then the elevator stops, obviously - Then the elevator is not at any floor - Then all contacts join together and the line is not seperated up/down anywhere. There is connection through all of the line Then in case i press a new floor button to restart the elevator - Because the line is not seperated..._"The voltage just goes both ways and the lift is requested to go up and down at the same time... absolutely no use"_ - Then i should be stuck in the elevator But old relay-controlled elevators simply don't behave like that. It's alwats possible to restart - after pushing stop button - from any position in the shaft. I think the _select direction_ logic works a bit different that you have illustrated. With the system you have illustrated, one - and *only* one - floor contact at a time must always be open, regardless of the car position in the shaft . Because if none are open (all joined together) the voltage will reach both directions which is of no use... and if both contacts around the car/carriage position are open, it would be "isolated" and the voltage will not reach any of the two directions. But is is impossible to always have only one contact open at a time. Because there will always be that split second where the car is precisely between two floors, and in that moment, either both contacts around the car could be open at the same time - or none of them A little side story: I've only been stuck once in my hole life in a relay-controlled elevator... even after 1000's of rides and thorough tests of all safety stop systems. It was in an 80's hydraulic DEVE where the _select direction_ logic got horrible confused and the elevator started to descend from the lowest floor, which meant that we crashed in the bottom of the shaft. I got it on video aswell STUCK in the elevator! To compare, i've been stuck in at least 10 digitally controlled elevators. Relay is best!
Heritage Elevators ELEVATORMUSEUM This is very interesting about using the stop button, then entering a new call with the line NOT broken (as the carriage doesn't break it all of the time). It's not something that I'd thought of, and what I'd love to do is an experiment to see what happens. Unfortunately i'm not in the position to do such a thing. I heard what ELEVATORMUSEUM are saying, but, what happens in a power-cut when all the relays are reset and the lift is between floors? This topic has helped me with the next video about the Express design. See 14:41 onwards - you see the LINE on the left. This line is never broken, either one or two switches are activated whilst travelling. Well HERITAGE ELEVATORS must be right here, and Express had the solution! Very interesting stuff and it's got me thinking! :)
Matt, I will look at the selectors again. I thought about the problem and I think this might be the answer: Actually, there is no issue with two contacts being opened at the same time other than that there are two floors at the same time that can't be selected. Again, I will carefully check the selectors - but when I was examinating them at night, it appeared like the opening of contacts has an overlap. That would mean that in case you would stop between floors, you couldn't select the nearest floors above and below the car but would be able to enter any other command for all other floors. Even tough the system might work differently in reality - it could work like I said. Will let you know. BTW: there are systems (some older Hauushahn) that indeed loose their position when pressing the emergency-stop. These lifts go down automatically to the next floor at slow speed after re-setting the toggle. (In Germany, mostly toggle-switches are used for emergency-stop.)
ELEVATORMUSEUM Hi, Cool, thanks. There must be provision to be able to select a floor even when the lift is between floors and line is not broken. One thing to mention is, Otis do not have any relays connected directly to the selector. Express do - each turn of the selector triggers a relay with many contacts available. So what I'm getting at is, everything you see on the carriage is ALL that's available. The only answer has to be - When the system is reset between floors (such as a power failure), there must be a logic circuit that says "when line is formed, elevator is not moving, ANY car call sends the lift to the ground floor regardless". This might even be initiated without a call present after a power cut. I like the Express lift's method of the line NEVER being cut. Take a look at watch?v=W5Wcj9EJ5Ao @8:38- the normally closed switches on the left form "the line", you'll see that a switch is activated before one is released so the line is never broken.
ELEVATORMUSEUM _"That would mean that in case you would stop between floors, you couldn't select the nearest floors above and below the car but would be able to enter any other command for all other floors"_ What if the elevator only has two floors?
Heritage Elevators After the STOP button, how did you try both up and down selections afterwards to confirm that the UP/DOWN logic is still working even when between floors? I wonder if the carriage was making 'any' connections to the floor bars at the time or whether it was 'completely clear' of any connections.
muy bueno amigo, no me imagino a los ingenieros de esos tiempos realizando los diseños de la conexiones de todos esos relés para hacer un circuito lógico de control para que el ascensor funcionara de forma correcta, tanto para que el ascensor supiera cuando subir, cuando bajar, cuando a llegado a la posición de la puerta de llamada seleccionada, cuando abrir las puertas, cuando activar el freno, como hacer para que el mismo pueda atender a las llamadas de las personas, creo que el peor trabajo era en de la persona que tuviera que realizar una reparación caso de una falla
Lovely video. I am building a model lift, but using microcontroller logic. This video helps a-lot with understanding how the relay-logic works, which will help me to convert that to code. I thing you guys call the industrial electronic controllers PLU's(Programmable Logic Unit?) - something like that anyway.
+VauxhallViva1975 Sorry, I missed this comment. Relay logic works in this way, serves down (and car calls) then up calls after. Some return to the terminal floor (normally ground floor) after a short duration. When you have a computer involved then two lifts or more become much easier to program. How many lifts and floors in your model lift?
+mrmattandmrchay Hi. Keeping things very simple for now. Single shaft, up to 10 floors on the controller, but the model only has 8 floors(6 floors, ground and basement). Your video was very useful to help me understand the basics of the relay-controllers(which lets be honest, are a thing of beauty). Perhaps I should make my model a relay-logic one!!!! (but I won't. PWM motor control etc are all built into the likes of the Micromite controller, so 90% of the hard work is done for you)
+VauxhallViva1975 After watching all these videos, I also am of a mind to build a scale model lift out of foamboard and balsa wood, but using real icecube relays, timer relays, limit switches, and an old 3 speed bi-directional box fan motor, lol. I see that one can buy packages of 120VAC DPDT 8-pin relays/bases for a few buckazoids, and 14-pin relays for not much more. RC airplane hobby sites also sell useful servos and sensors as well, but they're not rated for 120VAC. Yes, it could be done much cheaper with an Arduino or Raspberry PI, but these old relay systems are just so beautiful.
Yes, those DIL relays are a dine-a-dozen on eBay, and would certainly be one way of doing things. Relay logic is a beautiful thing, but complex. I think some of the relays used in the relay-logic controllers used special arrangements of contacts, and probably not all of them were standard contact arrangements, but perhaps I am wrong. IF I am right, some of those special contact arrangement could be difficult to reproduce with standard relays. I would love to be proved wrong on that though! ;)
Hi Matt, it's superb watching your excellent animated demo about OTIS pie plate style selectors. I'm kind of trying to convert this relay logic into an animated lift simulator app as a part of a programming course I am doing. A purely digital approach would be a lot easier (ie having a 'floor' variable that stores the floor number (0-3 in my sim) instead of a mechanical (ie animated interactive objectives that interact with each other) selector but these selectors are the accompanying control cabinet are of great fascination to me. Deciding which direction the lift needs to go to pick up calls has always been a bit of a mystery to me. Even more so, changing direction. In your animation, you have an 'Up calls available' and 'Down calls available' box at the top/bottom of your direction 'line' but where do these come from? Am I right in assuming that these come from the far (right) side of the slowdown relay (in your controller)? That would make sense to me.
There is an extra optimization to be made. If, at the very end of the video, a bloke was on "G" pressing an UP call, the elevator would hit the UP request at 1 and switch to UP mode without reaching floor "G". It's better for the elevator to go to the furthest UP call, not the closest.
Well, I was explaining using that battery just to point out that the motor direction changes using relays. This video was explaining more about the floor selector than the motor direction. But firstly, it depends if the motor is DC and AC. What actually happens with an AC MOTOR, this uses 3 PHASE mains power. I'll call them phase A, B and C and try and explain as simply as I can. On the lift motor there will be 3 electromagnets, I'll call them 1, 2 and 3. So on one cycle of the AC, each phase has it's own "peak" of maximum power. This goes from Phase A to B to C to A to B to C, etc. This can be used to attract the motor on a circular journey. If I connect Phase A to electromagnet 1, Phase B to 2, Phase C to 3 - the motor will turn in one direction. Then when I disconnect the power and apply the brake, the lift stops. To go the other way, relays switch different phases to different magnets. So now, Phase A to electromagnet 3, Phase B to 2, Phase C to 1. Now the motor goes the other way. For a DC MOTOR, things are different. Check out this video as this explains it perfectly... ua-cam.com/video/-qS85aIvleQ/v-deo.html Hope that helps?
Thanks very interesting! Would a simple lift serving only 2 floors, ground and first have a moving selector? I know all you'd have is on ground floor a DHC and on First an UHC. The car would only have a G and 1 switch with a floor indicator and door motor activator.
Good question! The carriage was developed to prevent having to take "wires down to switches" in the lift shaft - imagine trying to find a fault with a levelling switch 'somewhere' in the lift shaft! But when you are dealing with low rise building of 2 (or possible 3) landings, it's not such a big deal. So it is then cheaper to go back with 'installing switches in the lift shaft' rather than constructing a carriage system, which would also increase maintenance of the unit. So in a building with only G and 1, no - I would not expect to see a moving selector. Thanks for the question.
Question: If the position of the rails determine when power is cut to the motor at the precise instant to make the carriage stop level with the floor, won't the characteristics of the motor change over time causing the carriage to go out of level over time? Or if the line voltage should fluctuate, changing the speed and/or torque of the motor, which would change the distance it takes from cutting power to the motor and when the carriage stops, causing it not to be level? Or relative humidity changes over time would change the resistance in the wiring, affecting the voltage drop and changing the line voltage ever slightly, etc., etc. I assume this is a problem for these older relay lifts?
None of the conditions you have mentioned would alter the stopping position of the lift. When the micro-switch is broken at each floor level the contactors de-energise and the Brake is applied. On a single speed lift the levelling accuracy permitted was + or - 1" or 25mm on 2 speed or polechanger lifts this was reduced to 10mm. Gearless DC drive lifts had to stop within 3mm under all load conditions.
I have a request. I don't know if you even know this, but in the future could you make a video of the logic that decides which elevator to send on an elevator system with multiple elevators on the same controller?
I certainly can. An interesting request and it's on the list of things to do. I had to work out how to route lifts in my liftsim program. See.. watch?v=JnBga8rbH98 See about 0:50 you can see the status of each lift on the right. I'd like to send you the 'handyguide.pdf' that shows you some of the icons and meaning of what each lift is doing, so PM me with your email and i'll send it. This gives you a rough idea, but I will make a video to explain it further. Not sure exactly when it'll be up, but as before, it's on the list!
mrmattandmrchay I have the handy guide, but this info is referring to a relay controlled elevator, not a digital controller, right? Because I was talking about relay logic.
upanddownadventures Ah I see. I do have a basic theory about this, but to make a video that shows my theory in an easy to understand movie could be a challenge! I'll have a think!
mrmattandmrchay I would expect there to be a number of different systems out there (as with the floor leveling systems) made by different manufacturers and for the scale of system needed. The most basic system would send the call to all the lifts in the system, canceling the call when it is answered. This would have the disadvantage that all the idle lifts would start moving when a call is made (your ding-dong Premier Inn lifts seem to do this). This would be an improvement over having individual call buttons at each floor as a lift would not stop if the call had already been answered before it reaches the appropriate switch in the carriage. A more advanced system would need to compare the position of the call with the locations (and other calls) on the car. Compromises would have to be made between efficiency (as few lift movements as possible) and customer satisfaction (having a lift arrive as quickly as possible). I saw a bank of three lifts onboard a 1980s ferry that seemed to be setup for maximum efficiency. If, for example, two of the lifts were on deck 5 (idle) and one was on deck 4 going down (with a car call for deck 2). An up call made on deck 4 would not be answered by one of the idle lifts on deck 5, instead it would be answered by the remaining lift once it had visited deck 2. The result of this was crowded lifts (as they were usually full) and long waits.
Isn't it simpler to place all these switches and contacts directly in the shaft? Russian elevators have them in the shaft, the floor switches can be mechanical or inductive, the slowdown and stop switches are usually inductive.
Алексей Рукин I can answer this question for you .It is far easier to troubleshoot components that are physically in the machine room than the shaft.Otis has a type of elevator with floor switches in the shaft .He is just showing one of the many different Otis installations.Well all the ones with selectors anyway.BTW it looks like an 6850 selector.i think he did a marvellous job.
exactly! But back in 1970s, this is what was available LOL!!... www.google.co.uk/search?q=computer+from+1970&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjW7M2qr5LZAhXRCuwKHfizBBMQsAQILw&biw=1018&bih=746
this is VERY informative! THANKS for sharingthis!
WHY NO SPACE
Relay logic is one of those things that's simple to understand but daunting to implement.
Yes, which is why I love it!!
A great video that can be understood by the layman. They would have saved a fortune if dual coil flip flop relays existed back then. You have a good method of explaining simple logic circuits.
Absolutely brilliant. You explain everything very well, your animations are easy to understand, and I learned a lot. Thanks!
harleybadger1 Thanks for your comment. This video is one of my favourite video tutorials because I took my time and it took 3 months to complete (in my spare time). So it was only uploaded when I was happy with everything. I love trying to explaining things from a beginner's point of view and glad you enjoyed it. Did you see this one yet...THE MASSIVELY INFORMATIVE LIFT/ELEVATOR VIDEO (p1)
mrmattandmrchay I just watched both parts, and I can say very well done indeed. The Allen-Bradley controller is familiar to me, I have seen it used in other scenarios here in the US. Your video editing, as well as your always-informative animation, make it very easy to understand.
+mrmattandmrchay thankyou for making this viedo it is so helpfull and i understand everthing .THANK YOU
+mrmattandmrchay i bet u carnt do a dedacated video to broadmoor sirens & how tey work h
Thank you SO much, I have one of these old Otis lifts on my maintenance route and you just answered more questions then I even thought of. Very clear and easy to understand with your visuals. Thank you!!!
no problems, glad you found it interesting. It's worth pointing out that this is just to give people an idea of how it works. The ACTUAL carriage can have loads more contacts on it - seperate ones for UHS, DHS (up hall stop, down hall stop) and so on. watch?v=Bc2F9DfDAiQ @6:40.
Also see watch?v=wbvIXYZDdlI as I've labelled the contacts at @5:48.
Thanks.
Awesome! It's amazing how much thought has gone to that.
my favourite lift device :)
Very well educative! I like this video! Can´t wait for the express logic explanation!
thanks for your comment :)
THANK you so much for your time in creating this video!
no probs :)
I'm a lift mechanic from OTIS, are you too? Absolutely brillant you explain that!
+titony54 Hi! I'm not actually a lift engineer but Ive had a life long interest in them and I know a few people from within the industry, mainly through youtube.
It really Facinates me how people designed these systems from prototypes to working models that have stood the test of time.
My career is electronic security so we do work with lift engineers from time to time with CCTV and Lift Access Control. At my company if you want to do something with a relay, I'm your man! Love messing around with relays timers and circuits.
I have several elevator parts including selectors that I may connect up sometime but it's difficult finding the time.
Thanks for your comment
Amazing! I have work in OTIS 5 years, I can't explain this elevators like you:)
Very nice explanation and animation. I'm amazed, who thought this system out. It's hard to understand, but to invent that system...wow!
this was my simplistic description, it's actually FAR more complicated as there are more brushes and contacts on the real device. + all those relays!!! :)
This is so, so well done + interesting! Thank you!
Now I wish I'd seen this before, thanks for sharing!
11:54 _"If the lift is not at a floor, the contacts join together"_
In case i press the stop button between floors
- Then the elevator stops, obviously
- Then the elevator is not at any floor
- Then all contacts join together and the line is not seperated up/down anywhere. There is connection through all of the line
Then in case i press a new floor button to restart the elevator
- Because the line is not seperated..._"The voltage just goes both ways and the lift is requested to go up and down at the same time... absolutely no use"_
- Then i should be stuck in the elevator
But old relay-controlled elevators simply don't behave like that. It's alwats possible to restart - after pushing stop button - from any position in the shaft. I think the _select direction_ logic works a bit different that you have illustrated.
With the system you have illustrated, one - and *only* one - floor contact at a time must always be open, regardless of the car position in the shaft .
Because if none are open (all joined together) the voltage will reach both directions which is of no use...
and if both contacts around the car/carriage position are open, it would be "isolated" and the voltage will not reach any of the two directions.
But is is impossible to always have only one contact open at a time.
Because there will always be that split second where the car is precisely between two floors, and in that moment, either both contacts around the car could be open at the same time - or none of them
A little side story:
I've only been stuck once in my hole life in a relay-controlled elevator... even after 1000's of rides and thorough tests of all safety stop systems. It was in an 80's hydraulic DEVE where the _select direction_ logic got horrible confused and the elevator started to descend from the lowest floor, which meant that we crashed in the bottom of the shaft. I got it on video aswell STUCK in the elevator!
To compare, i've been stuck in at least 10 digitally controlled elevators. Relay is best!
Heritage Elevators ELEVATORMUSEUM This is very interesting about using the stop button, then entering a new call with the line NOT broken (as the carriage doesn't break it all of the time). It's not something that I'd thought of, and what I'd love to do is an experiment to see what happens. Unfortunately i'm not in the position to do such a thing.
I heard what ELEVATORMUSEUM are saying, but, what happens in a power-cut when all the relays are reset and the lift is between floors?
This topic has helped me with the next video about the Express design. See 14:41 onwards - you see the LINE on the left. This line is never broken, either one or two switches are activated whilst travelling. Well HERITAGE ELEVATORS must be right here, and Express had the solution!
Very interesting stuff and it's got me thinking! :)
Matt,
I will look at the selectors again. I thought about the problem and I think this might be the answer: Actually, there is no issue with two contacts being opened at the same time other than that there are two floors at the same time that can't be selected. Again, I will carefully check the selectors - but when I was examinating them at night, it appeared like the opening of contacts has an overlap. That would mean that in case you would stop between floors, you couldn't select the nearest floors above and below the car but would be able to enter any other command for all other floors. Even tough the system might work differently in reality - it could work like I said. Will let you know.
BTW: there are systems (some older Hauushahn) that indeed loose their position when pressing the emergency-stop. These lifts go down automatically to the next floor at slow speed after re-setting the toggle. (In Germany, mostly toggle-switches are used for emergency-stop.)
ELEVATORMUSEUM Hi, Cool, thanks.
There must be provision to be able to select a floor even when the lift is between floors and line is not broken.
One thing to mention is, Otis do not have any relays connected directly to the selector. Express do - each turn of the selector triggers a relay with many contacts available. So what I'm getting at is, everything you see on the carriage is ALL that's available.
The only answer has to be - When the system is reset between floors (such as a power failure), there must be a logic circuit that says "when line is formed, elevator is not moving, ANY car call sends the lift to the ground floor regardless". This might even be initiated without a call present after a power cut.
I like the Express lift's method of the line NEVER being cut. Take a look at watch?v=W5Wcj9EJ5Ao @8:38- the normally closed switches on the left form "the line", you'll see that a switch is activated before one is released so the line is never broken.
ELEVATORMUSEUM
_"That would mean that in case you would stop between floors, you couldn't select the nearest floors above and below the car but would be able to enter any other command for all other floors"_
What if the elevator only has two floors?
Heritage Elevators After the STOP button, how did you try both up and down selections afterwards to confirm that the UP/DOWN logic is still working even when between floors?
I wonder if the carriage was making 'any' connections to the floor bars at the time or whether it was 'completely clear' of any connections.
Well done!
I enjoy your sens(c)e of humo(u)r, too.
This was AWESOME. Had a blast understanding it. Now just need to understand how the motor changes directions electrically 😏
See here ua-cam.com/video/wwONptWo8P4/v-deo.html as part of this video goes through it :)
@@mrmattandmrchay Oh wow, thank you so much!
muy bueno amigo, no me imagino a los ingenieros de esos tiempos realizando los diseños de la conexiones de todos esos relés para hacer un circuito lógico de control para que el ascensor funcionara de forma correcta, tanto para que el ascensor supiera cuando subir, cuando bajar, cuando a llegado a la posición de la puerta de llamada seleccionada, cuando abrir las puertas, cuando activar el freno, como hacer para que el mismo pueda atender a las llamadas de las personas, creo que el peor trabajo era en de la persona que tuviera que realizar una reparación caso de una falla
This remind# me of the mechanical rotary stepping switches of 1950’s telephone switching equipment.
Brilliant video.
Excellent video. Thank you!
thanks :)
10000 views spot on. Congrats. And great vid :-)
Lovely video. I am building a model lift, but using microcontroller logic. This video helps a-lot with understanding how the relay-logic works, which will help me to convert that to code. I thing you guys call the industrial electronic controllers PLU's(Programmable Logic Unit?) - something like that anyway.
+VauxhallViva1975 Sorry, I missed this comment. Relay logic works in this way, serves down (and car calls) then up calls after. Some return to the terminal floor (normally ground floor) after a short duration. When you have a computer involved then two lifts or more become much easier to program. How many lifts and floors in your model lift?
+mrmattandmrchay Hi. Keeping things very simple for now. Single shaft, up to 10 floors on the controller, but the model only has 8 floors(6 floors, ground and basement). Your video was very useful to help me understand the basics of the relay-controllers(which lets be honest, are a thing of beauty). Perhaps I should make my model a relay-logic one!!!! (but I won't. PWM motor control etc are all built into the likes of the Micromite controller, so 90% of the hard work is done for you)
+VauxhallViva1975 After watching all these videos, I also am of a mind to build a scale model lift out of foamboard and balsa wood, but using real icecube relays, timer relays, limit switches, and an old 3 speed bi-directional box fan motor, lol.
I see that one can buy packages of 120VAC DPDT 8-pin relays/bases for a few buckazoids, and 14-pin relays for not much more. RC airplane hobby sites also sell useful servos and sensors as well, but they're not rated for 120VAC.
Yes, it could be done much cheaper with an Arduino or Raspberry PI, but these old relay systems are just so beautiful.
Yes, those DIL relays are a dine-a-dozen on eBay, and would certainly be one way of doing things. Relay logic is a beautiful thing, but complex. I think some of the relays used in the relay-logic controllers used special arrangements of contacts, and probably not all of them were standard contact arrangements, but perhaps I am wrong. IF I am right, some of those special contact arrangement could be difficult to reproduce with standard relays. I would love to be proved wrong on that though! ;)
Hi Matt, it's superb watching your excellent animated demo about OTIS pie plate style selectors. I'm kind of trying to convert this relay logic into an animated lift simulator app as a part of a programming course I am doing. A purely digital approach would be a lot easier (ie having a 'floor' variable that stores the floor number (0-3 in my sim) instead of a mechanical (ie animated interactive objectives that interact with each other) selector but these selectors are the accompanying control cabinet are of great fascination to me.
Deciding which direction the lift needs to go to pick up calls has always been a bit of a mystery to me. Even more so, changing direction.
In your animation, you have an 'Up calls available' and 'Down calls available' box at the top/bottom of your direction 'line' but where do these come from? Am I right in assuming that these come from the far (right) side of the slowdown relay (in your controller)? That would make sense to me.
There is an extra optimization to be made. If, at the very end of the video, a bloke was on "G" pressing an UP call, the elevator would hit the UP request at 1 and switch to UP mode without reaching floor "G". It's better for the elevator to go to the furthest UP call, not the closest.
Great Video. Can you further elaborate on how the motor polarity changes to move up and down. did'nt quite get that part.
Well, I was explaining using that battery just to point out that the motor direction changes using relays. This video was explaining more about the floor selector than the motor direction. But firstly, it depends if the motor is DC and AC.
What actually happens with an AC MOTOR, this uses 3 PHASE mains power. I'll call them phase A, B and C and try and explain as simply as I can. On the lift motor there will be 3 electromagnets, I'll call them 1, 2 and 3.
So on one cycle of the AC, each phase has it's own "peak" of maximum power. This goes from Phase A to B to C to A to B to C, etc. This can be used to attract the motor on a circular journey. If I connect Phase A to electromagnet 1, Phase B to 2, Phase C to 3 - the motor will turn in one direction. Then when I disconnect the power and apply the brake, the lift stops.
To go the other way, relays switch different phases to different magnets. So now, Phase A to electromagnet 3, Phase B to 2, Phase C to 1. Now the motor goes the other way.
For a DC MOTOR, things are different. Check out this video as this explains it perfectly...
ua-cam.com/video/-qS85aIvleQ/v-deo.html
Hope that helps?
Tough life of an engineer before PLCs
+Eugene Zagidullin Yes indeed but far more interesting to watch ;)
love it , thank you
Thanks :)
Thanks very interesting! Would a simple lift serving only 2 floors, ground and first have a moving selector?
I know all you'd have is on ground floor a DHC and on First an UHC. The car would only have a G and 1 switch with a floor indicator and door motor activator.
Good question! The carriage was developed to prevent having to take "wires down to switches" in the lift shaft - imagine trying to find a fault with a levelling switch 'somewhere' in the lift shaft!
But when you are dealing with low rise building of 2 (or possible 3) landings, it's not such a big deal. So it is then cheaper to go back with 'installing switches in the lift shaft' rather than constructing a carriage system, which would also increase maintenance of the unit.
So in a building with only G and 1, no - I would not expect to see a moving selector.
Thanks for the question.
Question: If the position of the rails determine when power is cut to the motor at the precise instant to make the carriage stop level with the floor, won't the characteristics of the motor change over time causing the carriage to go out of level over time?
Or if the line voltage should fluctuate, changing the speed and/or torque of the motor, which would change the distance it takes from cutting power to the motor and when the carriage stops, causing it not to be level?
Or relative humidity changes over time would change the resistance in the wiring, affecting the voltage drop and changing the line voltage ever slightly, etc., etc.
I assume this is a problem for these older relay lifts?
None of the conditions you have mentioned would alter the stopping position of the lift. When the micro-switch is broken at each floor level the contactors de-energise and the Brake is applied. On a single speed lift the levelling accuracy permitted was + or - 1" or 25mm on 2 speed or polechanger lifts this was reduced to 10mm. Gearless DC drive lifts had to stop within 3mm under all load conditions.
I have a request. I don't know if you even know this, but in the future could you make a video of the logic that decides which elevator to send on an elevator system with multiple elevators on the same controller?
I certainly can. An interesting request and it's on the list of things to do. I had to work out how to route lifts in my liftsim program. See..
watch?v=JnBga8rbH98 See about 0:50 you can see the status of each lift on the right.
I'd like to send you the 'handyguide.pdf' that shows you some of the icons and meaning of what each lift is doing, so PM me with your email and i'll send it. This gives you a rough idea, but I will make a video to explain it further.
Not sure exactly when it'll be up, but as before, it's on the list!
mrmattandmrchay I have the handy guide, but this info is referring to a relay controlled elevator, not a digital controller, right? Because I was talking about relay logic.
upanddownadventures Ah I see. I do have a basic theory about this, but to make a video that shows my theory in an easy to understand movie could be a challenge! I'll have a think!
mrmattandmrchay I would expect there to be a number of different systems out there (as with the floor leveling systems) made by different manufacturers and for the scale of system needed.
The most basic system would send the call to all the lifts in the system, canceling the call when it is answered. This would have the disadvantage that all the idle lifts would start moving when a call is made (your ding-dong Premier Inn lifts seem to do this). This would be an improvement over having individual call buttons at each floor as a lift would not stop if the call had already been answered before it reaches the appropriate switch in the carriage.
A more advanced system would need to compare the position of the call with the locations (and other calls) on the car. Compromises would have to be made between efficiency (as few lift movements as possible) and customer satisfaction (having a lift arrive as quickly as possible).
I saw a bank of three lifts onboard a 1980s ferry that seemed to be setup for maximum efficiency. If, for example, two of the lifts were on deck 5 (idle) and one was on deck 4 going down (with a car call for deck 2). An up call made on deck 4 would not be answered by one of the idle lifts on deck 5, instead it would be answered by the remaining lift once it had visited deck 2. The result of this was crowded lifts (as they were usually full) and long waits.
If I pressed the down button on the call and pressed the Up on the Car, does this cancel out any programmed events?
What about if there was 2-x amount of cars liked together? like 3 cars? What would the system have to do then.
Wow! I can't imagine the complexity of a bank of elevators in a tall building using relays! That would be insanely complex!
Hungry Guy wtc twin towers had this Otis relays system and there was 110 floors...
Is it ever possible for a lift to shoot past the top floor and crash into the top of the lift shaft due to an electronic failure?
ELPaso1990TX yes it is.Not very often but it has happened.
Now it can be done with a micro and resolver.
good
thanks
14:37 onwards is totally me xD
Awesome video though!
It's still on my never ending list of videos to complete ;)
Geico?
Isn't it simpler to place all these switches and contacts directly in the shaft? Russian elevators have them in the shaft, the floor switches can be mechanical or inductive, the slowdown and stop switches are usually inductive.
Алексей Рукин I can answer this question for you .It is far easier to troubleshoot components that are physically in the machine room than the shaft.Otis has a type of elevator with floor switches in the shaft .He is just showing one of the many different Otis installations.Well all the ones with selectors anyway.BTW it looks like an 6850 selector.i think he did a marvellous job.
the lift is going to fast to stop instantly on the next floor if the call switch is on, There is several things missing from this
I'm sure there are many things missing, but it's just the principle that I'm teaching here so that 'anyone' can understand (hopefully!)
The link in the description does not work in the mobile client (youtube.com… missing). Can you fix that? :)
Many thanks for noticing, I've updated the description.
why so complicated.....an arduino with encoder do the job
..ok maybe they did not have one at this time....:)
interesting Video....
exactly! But back in 1970s, this is what was available LOL!!... www.google.co.uk/search?q=computer+from+1970&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjW7M2qr5LZAhXRCuwKHfizBBMQsAQILw&biw=1018&bih=746