Here's a layman's explanation of what is going on: This motor is designed to run at constant RPM (Hence it is a synchronous motor) but when it is off it takes a lot of energy to get it spinning because its magnets aren't in sync yet. To make it easier to start, the housing of the motor is left free spinning at first and electricity is put in, which makes the housing spin up to full speed. When that happens, the guy with the big wheel starts putting a brake on the housing, which brings the motor out of full speed, and the rotor inside starts to spin to compensate. By slowly putting the brake on, the motor can be made to start up whatever the load is, until finally the motor housing stops spinning altogether and the rotor is driving the load at speed. Its a really brilliant way of making something work for a relatively co
K. Meinzer *its a really brilliant way of making a motor work for a relatively constant load without requiring more horsepower for the startup condition.
+K. Meinzer Why didn't you just edit your original posting instead? Anyway, wow, that seems like a weird way to have to start something that's just electric. I'm glad we don't have to do that with much newer equipment. It kind of reminds me of starting old big diesel engines with small engines -- "pony motors" or pony engines -- except that this doesn't have a smaller motor hooked to it.
An interesting thing is that 60 Hz was also a parralell standard in Europe as well during that period. (Not sure if it came from US or if it always been that way). (At least in my country.)
William Sheppard THAT OLD?? WOW!! Still running strong!! Must be quality! And synchronous motors are efficient, so I guess it won't need to be replaced anytime soon!
Some CEILING FANS use motors like that, BTW, but they use a spring to self-start. They're the ones that are really small and lightweight, and typically have a cord and plug. They're probably not common in the USA, but they are common in the Philippines, and other parts of Asia. They're known as "mini ceiling fans".
love these motors they will go for 300 years I pulled a 2 hp century american repulsion motor out of a field - it had a damn rats next in it - cleaned it up vacuumed etc - oil bath bearings - went first go and runs like a sowing machine - these machinist engineers made things to last.
@@markflierl1624 I have to agree picked a massive 90 year old century motor made in the usa - been in rain in a field and had a rat living in it (found the nest) cleaned it up and it fired and works like a sowing machine 1st go - if you saw the photos you would not believe it.
90 year old syncro motor/ almost brand new switch gear. We had these at a steel rolling mill in Cleveland untill just a few years ago. They ran large 250 volt DC generators that provided power to slitters and narrow line pinch mills. The syncro motors helped correct the power factor for the plant.
I had a similar synchronous motor with 220Vdc generator. The MCC cabinets were made about 1928. They were wood and concrete and looked like 10 ft tall kitchen cabinets.
Thanks for the bit of history. I took a machines class back in the 1970s whose lab looked a bit like the set from the Frankenstein movie. The synchronous motor was pretty neat. It was about 10 HP or so. It is pretty cool that with a little tweaking, you can make either leading or lagging phase. I never had to use that in actual practice. The facility where I worked was mostly office equipment and lighting, so a capacitor bank was all that was necessary to correct the power factor.
@@zinckensteel I took Machines at a University which had a positively ancient lab, but at least the principles were sound. I worked in an office for most of my work life. Some of my relatives worked in a steel mill. I never got the chance to tour because I was under 18 at the time, and mill policy was no one under 18 allowed in.
I love this! My dad was one of the fathers of solid-state motor control but he loved old tech, whether it was steam, early diesel, or olde-tyme electric, and I wish to God he was still alive to see this! He'd love it even more than *I* do!
@@versedbridge4007 yeah does sound like my 35 plus year old Kenmore. Keeps on going though! Get something new and see if your Samsung will run that long. Awe yea and I'll get a text when the spin cycle is done on my washing machine.
I think I get how it works - it's like the predecessor to modern soft start technology using mechanical means, letting the motor housing to rotate initially then gradual braking to get the housing to slow down, the magnetic field counter force starts the rotor spinning the opposite direction and the slow braking effect brings the load on gradually reducing inrush current, clever and simple, I love it!
+deezelfairy It's because of a lack of starting torque. Synchronous motors of this size usually don't even start under their own power because line frequency is too fast for them and they just sit there and hum. You can see in the video when it is starting up that the rotor doesn't even budge but after the thing gets going it can actually make enough torque to start rotating the line off the inertia of the stator.
I though sync motors needed a pony motor to get started. I guess this is what deez is suggesting, the outer stator is a rotor, but to get that amount of mass spinning I would think still needs a good lump of power, maybe that's why it hummed so much on start.
They start the stator into rotation, by a secondary small asynchronous motor, thats attached with a belt or chain of some sort, I can't tell by picture, because it's behind the stator. Once it comes into step with synchronous speed they start applying the brakes on the housing, of the stator.
@@victordubowski1276 The motor doesn't use a start motor at all. The motor housing is energized and spins due to repulsion with the run rotor. As the brake is applied, the rotor starts to spin in the opposite direction until the housing fully stops and the rotor is up to operational speed. An elegant design.
I used to motivate myself watching this while I was preparing for one of the toughest competitive exams for engineers in India. Today I have got a job of class one executive Electrical Engineer. Now looking at this video has made me nostalgic...
@@abdulazizhawsah9884 Joining is getting delayed due to corona virus condition. Let's see how does it look like.. in india, jobs are classified in descending order as group A, group B, group C etc. Group A jobs are also called Class 1 jobs or sometimes Executive job..
Ive seen a lot of synchronous motors (worked in a paper mill) but never one that had a "soft start" like that before. Really great to see that category of motor running. Looks about 240 rpms.
Great! Have not seen a super-synchronous motor in quite a while these were often used in cotton mills and for driving large compressors. This one will run forever THANKS for the treat...Dave S.IEEE
The inventor Lawrence Hammond used very small synchronous motors of his own invention first in his electric clocks and then in his famous electric organs. The motors' ability to run at one continuous speed for an indefinite period of time would, of course, be necessary for accuracy (in the clocks) and for sustaining a constant musical pitch (in the organs).
The old engineers knew what they were doing. Not possible: Impossible. Instead of VFDs and all other sorts of complex solutions, just use the most simple mechanical solution possible, which can not randomly fail btw. and call it a day. Lovely.
Steel alloy synchronous motors are like asteroids: their only terminal velocity is what has yet broken them. What a mighty beast and oh how great luck I am to witness such magnificence.
I would say that inside the casing between the stator and the large gear there IS a planetary gear set. You can see the large gear if you look through the stator to just beyond the poles.
Synchronous motors like this have very little starting torque but are extremely efficient. Complex electrical gear is required to protect the motor in cases of overheat or loss of line frequency synchronizaion.
They sure don't build them like that anymore and it's comical how they underrated motors back then. I bet she has the capacity to pull 1000 HP. Great video, glad to see that machine still functioning.
+fla playa Yeah in contrast with today where you buy power tools and vacuum cleaners and they use this bullshit "x hp 'developed' " rating! you might see a bandsaw or something with a dinky little power cord and the label might say " 2 hp developed" and the motor is like the size of a softball, 2 hp yeah right!!!! I have a 1928 Century repulsion-induction motor that is 2 hp, it weighs 290#
fla playa No, it is positively 2 hp it states it on the motor plate, it's 60 cycles, 220 v single phase 1165 rpm ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-U1SlR7dMbLg.html
What is cool to me, is that it looks like this is actually still being used somewhere,, not in a museum. Is it possibly for some public utility like a ventilation fan for a subway or something ?
Simontay: This is a repulsion start motor. The spinning hub is the repulsion windings that spin up first and allow it to be used as a clutching mechanism to the main rotor. If the brake was fully applied at start the motor would sit there buzzing very angrily at you. Induction motors don't like being stalled.
A giant Hammond Organ... Laurens Hammond invented the synchronous motor. Star-delta works on polyphase induction motors... synchronous motors have lower torque, so must be helped to start... hence the two-stage, two-switch method to start your Hammond organ. Wiki has an excellent article on this, although I don't believe that they cover this exact scheme. Great video! Ungodly noise on startup... I've had crashed sound cards make that exact same noise.
+scowell While directly line-driven synchronous motors may have very low startup torque and require slip to limit startup (a stalled motor acts almost like a dead short), modern synchronous motors with VFDs can provide massive torque by letting the VFD provide current limiting instead of the motor - the only limit to torque is the motor and VFD startup current limit. That's why modern locomotives are diesel-electric - full torque and 3000+HP available from 0RPM/dead-stop without the ginourmous and notoriously unreliable mechanical transmission. The newest generation of cordless power tools are going brushless synchronous as well. Same power and torque using smaller motors, simpler/no gearbox and no brushes to wear down.
+Teardown Dan The classic synchronous motor such as found in old electric clocks has no startup torque including this one. It is being spun up by another motor, likely a 3 phase induction motor. Most big VFDs are induction motors and also are not synchronous. However, brushelss DC motors have a permanent magnet rotor and a rotating stator field. Cordless drills do still have a gear reduction.
Marv Kausch A brushless "DC" motor is little more than a synchonous motor with the rotor field replaced with a permanent magnet and some form of position feedback to make the driver generate the correct stator drive timings to make it turn at a given speed for a given load.
GE does make a synchronous motor that has a very heavy amortisseur winding in the salient pole piece faces. This allowed the synchronous motor develop a much higher starting torque than a motor with a light (damper) winding. One of the motors I was familiar with was a synchronous motor driving a chipper disc in a plant that made ceiling tiles - not a good choice for a sync. motor because it would be knocked out-of-sync frequently, but the motor sometimes operated without any load for an extended period of time. The motor was rated 350 HP at 514 RPM.
Can you imagine the starting torque and the electrical demand if the stator was permanently stationary? It would probably register on the transmission grid every time. Temporarily swapping the roles of the rotor and stator is a clever way to get it started efficiently…
Looking at my old GE-Canada synchronous motor catalog, I believe GE called this a "Super-Synchronous" motor. Most large synchronous motors utilize squirrel cage bars in the rotor for starting on 3-phase AC, and a separate exciter unit is used, as seen here when the camera rotates over to the 2 guys at the electrical cabinet. Other synchronous motors have the exciter on the rotor shaft, opposite end of the output shaft. Honestly, I had no idea that the stator rotated to start the motor, I assume that the fellow is turning a hydraulic brake valve to slow and finally lock-down the stator, after the rotor is up to synchronous speed. I believe that there are squirrel cage bars for the AC stator to react with and start spinning around the rotor. The spinning field must cause the rotor to develop massive starting torque. Motor looks to be driving a very large belt. In my catalog, the super-synchronous motors were driving cement factory equipment. This is a GREAT video!!! It is so wonderful to see an old, open motor in service today, most new sync and induction motors of high HP look like enclosed boxes...booring!!! Thanks for this awesome video!!
When I was an apprentice, there wer some really great motors, ie:DELCO has a 3/4 hp motor 1 phase, but to replace that motor with a modern one was about a 5 hp, also WAGNER had a wonderful 1 phase motor1.5 hp repulsion start induction run to reverse it yoy moved the brushes 90 degrees, it also was a hernia buster, a new motor was probably 5hp -7.5, yes They do not make them like that anymore , the basic synchronous motors were 1800RPM, and every one I saw drove a large AMMONIA REFRIGERATION COMPRESSORS NH3, or R717. .🇺🇸🇺🇸🇺🇸🇺🇸
Right? When I was a kid we had an (old at that time), electric fan that was reversible, the sounds that induction motor made when I reversed it at full speed as it decelerated, reversed and came back up to speed were great. Of course it got very hot if I did it several times in a row, probably why I don't have that fan anymore ;)
When the motor first starts, the motor housing itself spins around the stationary shaft. As the rpm's increase the guy turning the wheel is applying brake to that spinning motor housing causing the shaft to use the increasingly held housing as a reaction surface, and as the housing is braked, the shaft begins to spin turning the machinery. Finally the housing is completely held and all electric power is turning the shaft alone and running the machine. Just a way to bring it up to speed.
I didn't understand until it stopped spinning! During the startup I was just "thaaaaat's not synchronous...with anything...". A non-static stator, just the thing to make my day! :)
Very interesting how the clutch system works. I figured out how it works just watching the video. I have a very old 1/4 HP Emerson motor that has a centrifugal clutch built right inside the motor giving the motor very high starting torque.
esta muy bueno el video, de hecho se puede apreciar de forma muy básica la explicación sobre el principio de arranque de un motor síncrono, este motor está diseñado para funcionar a RPM constantes (por lo tanto, es un motor síncrono), pero cuando está apagado se necesita mucha energía para que gire porque sus imanes aún no están sincronizados. Para facilitar el arranque, la carcasa del motor se deja girando libremente al principio y se pone electricidad, lo que hace que la carcasa gire a toda velocidad. Cuando eso sucede, la persona con la rueda grande comienza a aplicar un freno en la carcasa, lo que saca el motor de la velocidad máxima, y el rotor interior comienza a girar para compensar. Al poner lentamente el freno, se puede hacer que el motor arranque sea cual sea la carga, hasta que finalmente la carcasa del motor deje de girar por completo y el rotor impulse la carga a gran velocidad
ez nem semmi , hogy kezzel utanna kell allitani dolgoknak. This is very facinating process to start up an electric motor with high voltage. thanks for the vid .
In one of their synchronous motor catalogs, this type was called the "super synchronous" motor, their photos showing them running in a cement plant. Most large, old synchronous motors are self-starting...They have a squirrel cage in their rotors so they start like a standard 3-phase induction motor to get them up to speed. As far as I am concerned, this type here requires alot to get it going. The standard synchronous motor is easy to start: Soft-start it like an induction motor and it is running!
I have no idea how this motor works, but the first thing I would hazard to guess would be old brakes=asbestos like some fibrous webbing or many small plates of asbestos friction material.
+Ethan Smith I'd guess the motor is a simple synchronous design. Since line-synchronous motors have almost zero torque at 0RPM, the original plant engineers got around that problem by letting the much lighter stator rotate and apply brakes to it after it got to speed to progressively transfer torque to the shaft instead of using a clutch and multi-speed transmission which would only gets used at startup once a day at most. With modern electronic controls, it should be possible to retrofit the motor with rotor position sensors and use an electronic drive to eliminate the brake. With asbestos being banned or restricted in an increasing number of countries, I doubt its braking pads have contained much if any of it in the past 20 years or so.
Ethan Smith I don't know if it does or not. It certainly wouldn't be the first time I hear of a factory using some 60+ years old equipment. Based on how modern the control/supply room looks, if it has been decommissioned, it must not have been that many years ago. (The video itself is from 2013.)
I work at the old Inland Steel mill in NW Indiana, we have a 3500hp 13,800v synchronous motor we use for a giant fan at the sintering plant. 250v DC field is all done with digital electronics.
Our local pulp and paper mill used to have a couple of huge pre 1920's 400+ hp wagon wheel type electric motors that ran various equipment at the site until they were replaced in the early 1990's
So a small motor brings the big rostator up to speed, which induces the starotor to rotate. Once that is up to speed, the manual brake brings the rostator down to stator mpode, with the starotor now operating as a rotor. Neat!
a big giant machine spinning makes an interesting video. an explanation of how the big giant spinning machine works makes an excellent video. as far as i can tell the guy is turning the wheel to windup a giant toy car spring to turn the big wheel
@@sjokomelk Keeping in mind that if it is also being used for power factor correction, that too would have to be factored in. But then again if the motor was sized at 2x of the load (something not all that uncommon back in the day) then it would be 130kW. Of course if the babbitt bearings on the line shaft (IIRC that's what this motor runs) are worn or not properly lubricated then that will raise the load to the motor. But if most of the machinery that had been connected to the line shaft has been removed, then the load could drop to next to nothing. And on and on. :)
I love how the guy starts it by feel from experience and then there are the two engineers with hard hats that monitor something I'm sure is important and probably feel really impressed that the guy just started it effortlessly :D
A gigantic version of a classic Hammond organ that to scale would be as long as a dam on a major river. As every church organist who knows one of these, starting one is not just flipping one switch and playing. There is a start switch spring loaded to off. Flip it on and hold it and hear a faint version of what you hear here till it gets up to speed a few to 20 seconds, whilst holding the starter flip the power on and let go of the start switch in a few seconds. Hammond's first product was a clock powered by a synchronous motor. When the power went off it had to be restarted with a knob on back. It was famous then came the organ which has to spin at exactly the same and constant speed to in tune.
