AFCA Forums Home
Home Search search Menu menu Not logged in - Login | Register

 Moderated by: Steve Cunningham, Rod Rogers, Larry Hancock
New Topic Reply Printer Friendly
Electric Motor Gurus  Rate Topic 
AuthorPost
 Posted: Tue Feb 6th, 2018 05:54 pm
  PMQuoteReply
1st Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline
Any idea what year this would be from?

Back To Top PMQuoteReply  

 Posted: Tue Feb 6th, 2018 05:57 pm
  PMQuoteReply
2nd Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline


Back To Top PMQuoteReply

 Posted: Tue Feb 6th, 2018 05:57 pm
  PMQuoteReply
3rd Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline


Back To Top PMQuoteReply  

 Posted: Tue Feb 6th, 2018 06:01 pm
  PMQuoteReply
4th Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline






Back To Top PMQuoteReply

 Posted: Tue Feb 6th, 2018 07:19 pm
  PMQuoteReply
5th Post
William Dunlap
AFCA Member


Joined: Fri Jan 31st, 2014
Location: Pukalani(hole In Heaven), Hawaii USA
Status: 
Offline
I use small synchronous motors in my projects, but they are small permanent magnet, no specified direction of rotation.

I searched Wikipedia for more info and came up with this I
Rather technical, and admittedly over my head by a little. It would be interesting to find out the use of this GE synchronous motor.


I'm also curious as to how specific direction of rotation is achieved but didn't find it on this site.


Cheers,
Bill

Last edited on Tue Feb 6th, 2018 07:21 pm by William Dunlap

Back To Top PMQuoteReply  

 Posted: Tue Feb 6th, 2018 07:21 pm
  PMQuoteReply
6th Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline
I don’t have the motor just the plate. An 850 H. P. motor would probably take up half my garage!

!!!!!!!!!!

Last edited on Tue Feb 6th, 2018 07:30 pm by Richard Daugird

Back To Top PMQuoteReply

 Posted: Tue Feb 6th, 2018 07:54 pm
  PMQuoteReply
7th Post
David Allen
AFCA Member
 

Joined: Mon Mar 6th, 2017
Location: Northport, Alabama, USA
Status: 
Offline
I would expect to see that (25 cycle with large HP) in something like New Orleans old pumping stations.

Back To Top PMQuoteReply  

 Posted: Tue Feb 6th, 2018 07:57 pm
  PMQuoteReply
8th Post
David Allen
AFCA Member
 

Joined: Mon Mar 6th, 2017
Location: Northport, Alabama, USA
Status: 
Offline
One of my favorite synchronous motor startups: :shock:


Back To Top PMQuoteReply

 Posted: Wed Feb 7th, 2018 04:08 am
  PMQuoteReply
9th Post
Jeff Jones
AFCA Member
 

Joined: Sat Oct 18th, 2014
Location:  
Status: 
Offline
@David yep...weird how they start that w/ the housing spinning up then applying a brake to it to slowly bring the rotor and load up to speed.

Back To Top PMQuoteReply  

 Posted: Wed Feb 7th, 2018 11:06 am
  PMQuoteReply
10th Post
David Allen
AFCA Member
 

Joined: Mon Mar 6th, 2017
Location: Northport, Alabama, USA
Status: 
Offline
Jeff Jones wrote: @David yep...weird how they start that w/ the housing spinning up then applying a brake to it to slowly bring the rotor and load up to speed.

Yes it is!  These very old synchronous 3-phase motors like this are started in a unique way which I will explain later.  The rotor has windings on it which create alternating north and south poles, just like a stator winding but inside-out.

When the motor is already running, these poles have a DC current through them to make them into electromagnets. While the motor is at speed, these "lock in step" with the alternating magnetic polarities of the stator, so that the motor is "synchronized" with the AC current frequency. It runs at an exact constant speed regardless of the load on the motor.

They are a form of induction-start / synchronous run. When the motor is at a standstill, the alternating field of the stator would move past the magnetic poles too quickly to "jerk them into motion" and pull the motor into synchronous running.  Instead, it uses a similar principle to the induction motor to start up.  For starting, the rotor winding is "shorted out" creating an effect similar to an induction rotor (with the shorted winding simulating the rotor bars). This method does not provide a high amount of torque and it puts a lot of current on the rotor winding due to the induction effect.  To mitigate the stresses on the motor, the system does two things. First, there is a "starting reactor" which is switched in series with the stator winding. This reduces the current going to the motor to a safe level for starting. The second (and most spectacular) way to allow starting is the freewheeling stator system. This effectively allows the motor to start without load, so that the small starting torque is enough.  Once it is up to speed, the contactors switch the rotor from "shorted" to "field current ON" and the motor locks into synchronous run. It also removes the starting reactor from the power circuit so the motor gets the full rated voltage. Then the brake is applied to stop the stator spinning and allow the rotor to power the load. The rotor below in this picture appears to be similar to the one in the video, but without the free stator design.



Newer synchronous motors use closer to an induction rotor design than the older ones. They actually have both the synchronous field winding, AND an amortisseur winding (like an induction motor) on the rotor. These can start by simply powering on the stator with 3-phase current (and no DC field current in the rotor) and then turning on the field once the motor is up to speed. These still don't have the starting torque of an induction motor, but they do have a lot more than the early designs. This picture shows a rotor with both field and induction winding.  Note the extra parts mounted on the shaft at the right end. This is the parts which provide the DC current to the field once it is running. There is a generator rotor and diode rectifier. These parts together are called the "exciter" for the motor. It can't provide field current until the motor is running since it depends on its own generator. This depends only on the induction winding to bring it up to speed. Then the exciter field is turned on to bring it into synch.



There are other varieties and starting systems too; but these are the two that dominate industry. :)

Back To Top PMQuoteReply

 Posted: Wed Feb 7th, 2018 11:14 pm
  PMQuoteReply
11th Post
Richard Daugird
AFCA Member
 

Joined: Tue Sep 12th, 2017
Location: Texas City, Between Hou. & Galveston, Texas USA
Status: 
Offline



Cleaned up pretty nice. 

Last edited on Wed Feb 7th, 2018 11:19 pm by Richard Daugird

Back To Top PMQuoteReply  

 Posted: Sat Feb 10th, 2018 01:17 am
  PMQuoteReply
12th Post
Levi Mevis
AFCA Member
 

Joined: Tue Feb 24th, 2015
Location: Elkhart, Indiana USA
Status: 
Offline
The reason why synchronous motors have to have something to start them (like in the video where it had the "housing" spinning up to start the motor) is because synchronous motors aren't self-starting motors traditionally (think of the old Hammond Clocks and organs which used synchronous motors in them) they almost always have to be spin started by hand or by means of another "self-starting" motor. Telechron for the longest time was the only manufacturer of electric clocks in the US that made a self-starting motor and they got started in 1912 and their clocks were prided as being the only clocks trusted in the US to be able to be synchronized by the power grid the Telechron motors (or rotors as they are actually referred to as) are a type of self-starting synchronous motor. It wasn't until the 1930s when Lanshire Clock Company of Chicago, Illinois, developed a self-starting motor of their own design (it was a monster compared to the Telechron motor but it was a self-starting motor of an original design none the less). Seth Tomas (General Time) of Thomaston, Connecticut also developed a self-starting synchronous motor for clock use of their own design, this motor came into being in the 1940s and was used in many clock radio and alarm clock designs up until the 1980s.

Back To Top PMQuoteReply

Current time is 04:36 pm  
AFCA Forums > Antique Fan Collectors Association > Pre-1950 (Antique) > Electric Motor Gurus Top



Beige Theme By: Di @ UltraBB
UltraBB 1.17 Copyright © 2007-2008 Data 1 Systems
Page processed in 0.2079 seconds (32% database + 68% PHP). 28 queries executed.