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LIM vs LSM

jolash

Member
I can't get all official on ya cause I'm no expert, but here's what I do know.

LIM- Magnet on the track is not always charged, requires a electrical charge. The magnet is charged up during loading/unloading. This type of motor is only capable of providing positive acceleration, and a separate braking systems are required. Requires extreme amounts of power (anyone who's been inside a Mr Freeze station during launch will know)

LSM- Magnet on the track IS always charged. It is a natural magnet, and can be used as a fail safe brake. Requires the careful synchronization of hundreds of computers to create a launch.

So it brings up the question "why use one or the other?" I can't honestly answer that. LIM coasters are getting few and far between the last few years though, so take that for what it's worth.

Lets also remember that LIMs need an extra brake system and require a lot more power, but I do believe are capable of reaching much greater speeds in a shorter time. I remember hearing that it was being considered retrofitting aircraft carriers with LIMs to launch jets.
 

Hobbes

Member
Interesting, thanks for the response.

You said that LIM launches require extreme amounts of power. Do LSM launches require significantly less?
 

jolash

Member
Hobbes said:
Interesting, thanks for the response.

You said that LIM launches require extreme amounts of power. Do LSM launches require significantly less?
You know, we'd have to ask someone who knows better.

If you take Maverick vs Wicked Twister, for example, I know they both demand so much power that they each have their own independent power supplies, which are used for those rides and those rides only and aren't tapped into by anything else in the park.

As for which requires more, I have to admit I truly don't know for certain, but I've always been under the impression that LIMs consume much more.

Making an educated guess, but I would say this because an LSM system is just a series of computers that are quickly reversing the polarity of each magnet as the train pulls through a launch. A LIM system on the other hand requires charging magnets with enough electricity to catapult a train.
 

Hixee

Flojector
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OK, I'm going to elaborate slightly as I think the real difference has been missed.

LIM stands for Linear Induction Motor. The name is already giving an indication as to the way these work. Basically you have a series of electromagnet plates placed along the track, attached to an AC current source. As the magnetic field is induced in these plates they generate an opposing magnetic field in the fins attached to the train (via eddy currents - basically the alternating magnetic field causes a current to be generated in the plate on the train, which then itself creates a magnetic field) and Lenz's Law states that opposing magnetic forces will repel each other - thus pushing the train along. Basically you control the speed of the train down the track by alternating how fast you change the frequency of the AC current.

LSM stands for Linear Synchronous Motor. This means that the fin attached to the train is a permanent magnet, and so is affected by the generated magnet field directly. All you have to do it charge one of the electromagnet plates behind the train to be the same as the back end of the fin (the front end is charged the opposite - like all dipole magnets). This then pushes the train along. In reality, they also charge the electromagnet plates in front of the train to simultaneously pull and push the train along. All you have to do is keep the pulse just ahead/behind the train all the way down the track.

So, what's the practical difference?

LIMs are simpler (that meaning the hardware to increase the frequency of an AC current isn't that complicated).
LSMs are more complicated (you have to have a clever control system to monitor the exact position of the train to ensure that the magnetic field is in the right place).

BUT

LIMs are generating currents inside the fins on the train, which causes heat to build up.
LSMs are capable of braking the train on the way back without any power. As the permanent magnet fins pass the plates in the launch track, they induce currents in the plates and (with eddy currents again) this generates an opposing magnetic force which slows the train down. You can't do this with LIMs because without any current flowing in the plates, it would just be two sets of metal plates passing each other. LSMs work in braking just like normal magnetic brakes on a coaster do. It's worth nothing that this effect is a fuction of several things; magnetic flux, distance between plates, etc, but crucially - speed. This is why you can't ever stop a train directly using static magnets. The train can slow down greatly, but you'll always notice some sort of friction device to actually bring the train to a stop*.

FINALLY on the topic of power consumption, I don't know this for sure but this is my educated guess. LIMs are activating the magnets down the whole launch track at the same time, which takes a lot of power. LSMs are only generating magnetic fields in the vicinity of the trains, and so don't require as much power (I don't imagine the more complicated control system uses up more than the difference), so that might be another factor which means LIMs are becoming less popular these days when compared to LSMs.

I think that just about covers it, I might have missed something, or messed up a detail or two, but that's about right.

*The topic talking about the Inverted Impulse coasters seems to suggest that they just run the LIMs in reverse for a very short amount of time to bring the train to a halt - but I've no confirmation of that just yet.
 

BBH

Active Member
A linear synchronous motor is a permanent magnet and can be used as reversible failsafe brakes, but as stated they take hugely sophisticated computer operating systems to manage.

Linear induction motors, on the other hand, are far simpler but take up vastly greater amounts of energy, because they run specifically on temporary electromagnetism on a three-phase power source.
 

_koppen

Active Member
I remember Sandor Kernacs said in an inerview years ago that LIM's used less power than LSM's, but that he thought that LSM's would be the more dominant one in the future, thanks to them also acting as brakes, making them less complicated. Turns out, he was right, I can't even remember the last LIM ride that was built.
 

bmac

Active Member
_koppen said:
I remember Sandor Kernacs said in an inerview years ago that LIM's used less power than LSM's, but that he thought that LSM's would be the more dominant one in the future, thanks to them also acting as brakes, making them less complicated. Turns out, he was right, I can't even remember the last LIM ride that was built.
Revenge of the Mummy in Universal Studios Singapore was built in 2010 and uses LIMs. But other than that their last LIM installations were the Backlot Stunt Coasters in 2005-06.
 
_koppen said:
I remember Sandor Kernacs said in an inerview years ago that LIM's used less power than LSM's, but that he thought that LSM's would be the more dominant one in the future, thanks to them also acting as brakes, making them less complicated. Turns out, he was right, I can't even remember the last LIM ride that was built.
It's the other way around, LSM units have better efficiency compared to LIM.
A LIM unit have an efficiency of between 30-70%, where as a LSM unit will do 60-90%.
LIM systems are much simpler than LSM systems, which is why they were more used in the past. The big advantage is that you don't need any extra brake system if the ride require an anti-rollback system, since the powerless LSM units works just as well as a normal brake-fin.
The next thing to be developed for LSM systems is to use them to reclaim the power of the moving train as it hits the brakes, Freishütz have this feature, but there are still some problems to solve before it will become a standard feature for every LSM launch coaster out there.

Source for the LSM/LIM efficiency, is an article on Coastersandmore.de: http://www.coastersandmore.de/rides/lim/lim_lsm.shtml
 

_koppen

Active Member
Yes, that is completely correct, I found the quote and i remembered it wrong.

Quote by IntaRide president Sandor Kernacs:

“Each has its advantages and disadvantages,” explains Kernacs. “The LSM coaster is a more complex design and requires more sensitive sensors, but it produces twice the force as the LIM for the same amount of energy, and you don’t need brakes because the LSM system acts as the brakes. The LIM is easier to design and maintain, but it only produces half the torque, and you must have an anti-rollback system because the LIMs will not brake. Eventually, I believe the LSM coasters will be favored over LIM coasters because of their higher efficiency.” *** Edited 9/16/2006 3:43:06 AM UTC by halltd***

And I agree with the ride at Bayern Park having problems, I've been spited by it two times already.
 

gavin

Administrator
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^ You haven't missed much; it's kind of a disappointing ride.
 

andrus

Active Member
Does anyone know the difference in power consumption between an LSM launch and a hydraulic cable launch (and maybe even a pneumatic one)?

I remeber that the reason to why Intamin introduced the hydraulic launch was because of the lower power consumption compared to LIM coasters (as well as being more powerful). And I remember reading somewhere that a hydraulic launch do not consume more energy than a regular lift hill ride would need to propell the train at the same speed. Since the introduction of LSM's however the hydraulic launch technology have more or less died. A cable launch obviously has more moving parts and should in theory be less prone to break downs. However I've experienced quite some issues with LSM rides as well. So I would be intrigued to hear the difference in power consumptions between the two technologies as well.
 

jolash

Member
andrus said:
Does anyone know the difference in power consumption between an LSM launch and a hydraulic cable launch (and maybe even a pneumatic one)?

I remeber that the reason to why Intamin introduced the hydraulic launch was because of the lower power consumption compared to LIM coasters (as well as being more powerful). And I remember reading somewhere that a hydraulic launch do not consume more energy than a regular lift hill ride would need to propell the train at the same speed. Since the introduction of LSM's however the hydraulic launch technology have more or less died. A cable launch obviously has more moving parts and should in theory be less prone to break downs. However I've experienced quite some issues with LSM rides as well. So I would be intrigued to hear the difference in power consumptions between the two technologies as well.
I'm no engineer but a hydraulic launch has got to be far less power consuming. LIMs/LSMs use electricity, obviously, while the power in a hydraulic motor is, well, from hydraulics. It's a mechanical motor vs an electric motor.
 

MouseAT

Active Member
I think the hydraulic launches are losing popularity due to their complexity, and the fact that they have a lot of mechanical parts that are constantly under strain and require maintenance.

As for the power consumption, I'd think that on average the hydraulic and LSM launches require similar amounts of power. If I remember rightly, the main difference is in peak power consumption, rather than average. Hydraulic coasters drain small amounts of power constantly when they pump the hydraulic oil into the accumulators, and use the accumulators as an energy storage system. LSM launches are electrically powered, so draw much larger amounts of power during the launch but very little at other times.

jolash said:
The power in a hydraulic motor is, well, from hydraulics. It's a mechanical motor.
Well yes, but there's more to it than that. The oil for the hydraulic motor has to be pumped into high pressure accumulators first, and that takes power.
 

_koppen

Active Member
andrus said:
Does anyone know the difference in power consumption between an LSM launch and a hydraulic cable launch (and maybe even a pneumatic one)?

I remeber that the reason to why Intamin introduced the hydraulic launch was because of the lower power consumption compared to LIM coasters (as well as being more powerful). And I remember reading somewhere that a hydraulic launch do not consume more energy than a regular lift hill ride would need to propell the train at the same speed. Since the introduction of LSM's however the hydraulic launch technology have more or less died. A cable launch obviously has more moving parts and should in theory be less prone to break downs. However I've experienced quite some issues with LSM rides as well. So I would be intrigued to hear the difference in power consumptions between the two technologies as well.
The main reason they developed the hydraulic launch was that they wanted a more powerful feel in the launch. With LIM/LSM coasters, you have the initial acceleration that is very intense, but then there is a major drop off in G's after the initial push. They wanted to change that with the hydraulic system, you will start with around a 2.2G launch and at the end of the launch still hitting around 1.9-2.0G's. There is very little drop of in power, and this can not be achieved using magnets, at least not 10 years ago, and I doubt somebody can build you a system that could be as powerful.

While i can believe that the hydraulic launches use less power than a magnetic one I seriously doubt that they would be similar to a regular lift hill in power consumption. Another big reason for going with the hydraulic launch at the time when they were introduced was that they were much more affordable. A magnetic launch would have putted almost a million dollar more on the tab. This has changed in recent years though.

Also as you say they are much more likely to break down, compared to a magnetic launch, but this is most often a soft ware issue, rather than a mechanical one (the moving parts do require some maintenance after hours). There are so many moving parts than needs to line up perfectly with a pretty complicated ride system.

I personally prefer the hydraulic launch by far, but as you said then are of a dying breed. Any park buying one now, that is not supposed to go 120km/h+ would be mad not to choose the LSM system, with almost no moving parts, and a pretty high durability.

gavin said:
^ You haven't missed much; it's kind of a disappointing ride.
Very good news!
 
andrus said:
Does anyone know the difference in power consumption between an LSM launch and a hydraulic cable launch (and maybe even a pneumatic one)?
If you assume that you use a similar train for each launch type and accelerate it in a similar fashion to a fixed top speed, then the train would require a certain power to get to that speed. Then you just divide the power required with the efficiency of the launch system. By doing that you will get the power consumption/launch for each launch system.
To be able to compare them you will need to know this efficiency number but almost all of them are unknown, but I would assume that a LSM and a Hydraulic system would be pretty much the same for the given case.
So mean power would be pretty much the same, a few systems might have higher consumption, like LIM.

But as koppen said, some systems work better than others depending on what you are looking for when designing a launch coaster.
LSM/LIM, "gentle launch" about 1 g, no moving parts.
Hydraulic, powerful 1-2.5 g's, pretty complex system
Pneumatic, "normal" to insane power, up towards 4 g's

But I assume that you ask about peak power, not mean. Then it's completely different.
A hydraulic/pneumatic system have a pump/compressor that builds up pressure into "shot tanks" over a long time, and then all that built up energy is released in a few short seconds. Since the compressor can work for about a minute to build up the required pressure between the launches means that you can use a less powerful unit, and you don't get any spikes in the power grid.
Older LIM/LSM (and The Hulk) units were connected directly onto the power grid, which meant that you draw all the power you need for the launch as you launch the train, this means massive spikes in the power system. To avoid this you can fit the system with a energy storage unit to smooth out the way the rides need power and make them kinder to the power grid. You could use flywheels, hydraulic systems (same as the Accelerator coaster system but with a generator instead of the winch drum), super capacitors (like Freishütz), etc. between the power grid and the LSM/LIM units. You charge these between the launches and they will deliver the burst of energy needed to launch the trains. By using these then you will get a similar power draw as any other accelerator coaster, and I'm pretty sure that this is the way most LSM/LIM launch coasters today work.

One thing I wonder though.
Since fine tuned LSM system is nearly as efficient as an electric motor, when will rides with lift-hills use LSM units instead of a lift hill motor and chains/cables. In theory then they should use more or less the same power to pull a train up the hill at the same speed. Is this the future of coasters with lifts? Or will we still see traditional lifts for a long time ahead?
 

jolash

Member
bergochdalbana said:
One thing I wonder though.
Since fine tuned LSM system is nearly as efficient as an electric motor, when will rides with lift-hills use LSM units instead of a lift hill motor and chains/cables. In theory then they should use more or less the same power to pull a train up the hill at the same speed. Is this the future of coasters with lifts? Or will we still see traditional lifts for a long time ahead?
I would say no. Maverick has a LSM lift and we haven't seen any since, not that I can recall. While this may theoretically use the same amount of power as a traditional lift, the reliability is abysmal. A regular old chain and motor is old, but well refined technology.
 
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