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Old October 10th, 2018, 09:50 AM   #1
milmat1
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480V/3PH/ dual speed motor contactor

I have an old turret lathe, it has a dual speed motor operated by an old Square-D NEMA1 contactor, which have failed.


The original contactor (starter) has 9 contacts for motor leads.

Low speed it connects L1 L2 & L3 directly to T1,T2 & T3 ..
High speed it connects L1,L2 & L3 to T4,T5, & T6 AND Connects T1, T2 & T3 all together for a STAR run.


I cannot seem to find a contactor like this, Any ideas on where to start ??



What is the standard procedure to use when working on these antique machines ?
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Last edited by milmat1; October 10th, 2018 at 09:57 AM.
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Old October 10th, 2018, 10:18 AM   #2
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Are L1-L2-L3 the supply to the contactor, and T1-..T6 the leads to the motor ?
edit: Or are there really 9 leads coming out of the motor ?
It may be separate windings, or tapped windings.
I would make this with 2 or 3 contactors, depending on exatly how the windings are to be connected. Without knowing exactly how the windings are interconnected, I cant really say.
It would be nice to have a diagram of the windings and a photo of the motor name plate.
Look inside the the lid of the motor terminal box. Often the winding connections can be found on a small diagram there.
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Last edited by JesperMP; October 10th, 2018 at 10:40 AM.
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Old October 10th, 2018, 10:22 AM   #3
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Hi, does the lathe, (motor) start at low speed and then go to hi speed, or does it have a manual switch that let's the operator choose which speed? If it's the first one, then you'd need a soft start, such as a Y Delta starter which is configurable to star run. If it's the second, then you could use a dual contactor set up that would use the line in both contactors and then whichever speed was selected then that one would feed the appropriate motor lead configuration. Hope this helps.
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Old October 10th, 2018, 10:39 AM   #4
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That sounds like a Pole Changing method, but you Americans have some strange ways with motors:
https://www.quora.com/What-is-the-el...control-method
Never seen it done on one contactor, have seen it done with a rotary switch.
In the link above there is a circuit diagram for using 3 contactors to get the same switching.
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Old October 10th, 2018, 10:41 AM   #5
scott.lawrence
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as BryanG said, you can accomplish this with three contactors
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Old October 10th, 2018, 10:46 AM   #6
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What you have is called a “2 speed 1 winding” motor, often abbreviated 2S1W. There are three different types of these motors, each using a different connection pattern and although the parts are the same on two of the types, they are often different on the third, so you’ll need to determine that first.

If the motor has two speeds but only lists one HP rating, then it is a 2S1W “Constant HP” version.

If the speed and HP are different by the same ratio, ie low speed is 1/2 of high speed and the nameplate shows two HP values with the low speed HP being 1/2 of the high speed HP, that is a 2S1W “Constant Torque” motor.

If the Speeds and HPs vary at a greater ratio, ie at 1/2 speed the HP shows as 1/4th of high speed HP, that is a 2S1W “Variable Torque” motor.

Once you determine that, you can go to a good Square D dealer and get a replacement starter or go to any of the other major player NEMA control manufacturers. It will not be on the shelf anywhere because VFDs have made these obsolete (which is another option by the way). Here is an A-B book on NEMA wiring diagrams, the 2S1W versions start on page 37. https://literature.rockwellautomatio...d005_-en-p.pdf

Many of the IEC suppliers will not have all of the options, so I’d steer clear of that option since you are unfamiliar with this in the first place. But if what you have is the 2S1W Variable Torque version, that’s called a “Dahlander” starter in IEC world.

Last edited by jraef; October 10th, 2018 at 10:58 AM.
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Old October 10th, 2018, 10:50 AM   #7
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Quote:
Originally Posted by BryanG
That sounds like a Pole Changing method, but you Americans have some strange ways with motors:
https://www.quora.com/What-is-the-el...control-method
The diagram in the Quora webpage is a good bet that it is actually how the windings are setup.
But there are actually more possibilities, more esoteric ways, that still fit the information given in the 1st post.
So I would get the information, just to be double sure.
Quote:
Originally Posted by BryanG
Never seen it done on one contactor,
Probably an integral motor starter combination made out of several contactors.
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Old October 10th, 2018, 11:02 AM   #8
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Now is a good time to upgrade. I would recommend wiring it in the high speed configuration and feed it with a VFD.
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Old October 10th, 2018, 11:13 AM   #9
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Quote:
Now is a good time to upgrade. I would recommend wiring it in the high speed configuration and feed it with a VFD.
That’s a good idea, but on something like a turret lathe where some operations may involve really rough duty like “plugging”, retrofitting with a VFD, although likely less expensive now, requires someone with experience in sizing and applying the VFD and braking options. There can be numerous pitfalls for the inexperienced. If you decide to do it, find a local panel shop that has retrofitted machine tools with VFDs.
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Old October 10th, 2018, 01:51 PM   #10
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I'm currently working on a turret lathe by Dowding and Doll . The motor control box contains 6 contactors - 2 for forward and reverse , 3 for speed control ( Dahlander as jraef mentioned ) and finally a contactor for the suds pump . this lathe also has a 2 speed gear box ( 4 to 1 ratio ) and a neutral position for braking . The 3 speed contactors looked like a start-delta at 1st sight , since 1 of the contactors was connected in star format . Again , as jraef mentioned , fitting a VFD will be a pain since some of the control relays are DC with capacitors to introduce timing delays . The hardest part will be getting reverse selected for backing taps out - the acceleration and deceleration settings will be tricky .
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Old October 10th, 2018, 02:14 PM   #11
milmat1
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Quote:
Originally Posted by JesperMP View Post
Are L1-L2-L3 the supply to the contactor, and T1-..T6 the leads to the motor ?
edit: Or are there really 9 leads coming out of the motor ?
It may be separate windings, or tapped windings.
I would make this with 2 or 3 contactors, depending on exatly how the windings are to be connected. Without knowing exactly how the windings are interconnected, I cant really say.
It would be nice to have a diagram of the windings and a photo of the motor name plate.
Look inside the the lid of the motor terminal box. Often the winding connections can be found on a small diagram there.
Yes L1 L2 & L3 are the supply conductors / 480V 3PH.


Quote:
Originally Posted by jraef View Post
What you have is called a “2 speed 1 winding” motor, often abbreviated 2S1W. There are three different types of these motors, each using a different connection pattern and although the parts are the same on two of the types, they are often different on the third, so you’ll need to determine that first.

If the motor has two speeds but only lists one HP rating, then it is a 2S1W “Constant HP” version.

If the speed and HP are different by the same ratio, ie low speed is 1/2 of high speed and the nameplate shows two HP values with the low speed HP being 1/2 of the high speed HP, that is a 2S1W “Constant Torque” motor.

If the Speeds and HPs vary at a greater ratio, ie at 1/2 speed the HP shows as 1/4th of high speed HP, that is a 2S1W “Variable Torque” motor.

Once you determine that, you can go to a good Square D dealer and get a replacement starter or go to any of the other major player NEMA control manufacturers. It will not be on the shelf anywhere because VFDs have made these obsolete (which is another option by the way). Here is an A-B book on NEMA wiring diagrams, the 2S1W versions start on page 37. https://literature.rockwellautomatio...d005_-en-p.pdf

Many of the IEC suppliers will not have all of the options, so I’d steer clear of that option since you are unfamiliar with this in the first place. But if what you have is the 2S1W Variable Torque version, that’s called a “Dahlander” starter in IEC world.

After investigating this today. You are exactly right. Thank You !
It appears I have a 2 speed constant HP Consequent winding motor. And will use a 5 pole / 3 pole contactor.
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Old October 10th, 2018, 06:14 PM   #12
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Quote:
Originally Posted by milmat1 View Post
Yes L1 L2 & L3 are the supply conductors / 480V 3PH.





After investigating this today. You are exactly right. Thank You !
It appears I have a 2 speed constant HP Consequent winding motor. And will use a 5 pole / 3 pole contactor.
The 5 pole contactors are likely unavailable now, but most people just do it with 3 x 3 pole contactors and the necessary mechanical interlocks.
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Old October 10th, 2018, 07:50 PM   #13
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Quote:
Originally Posted by jraef View Post
but on something like a turret lathe where some operations may involve really rough duty like “plugging”, retrofitting with a VFD, although likely less expensive now, requires someone with experience in sizing and applying the VFD and braking options. There can be numerous pitfalls for the inexperienced.
What are those pitfalls you speak of, I think it's a piece of cake . Give details please.
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Old October 10th, 2018, 08:46 PM   #14
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What are those pitfalls you speak of, I think it's a piece of cake . Give details please.
Listening to salesmen telling you what size of drive to buy, based on them wanting to be cheaper than the next guy to get the order. Buying a cheap Chinese no-name VFD from Fleabay that is marketed by people that lie about their specs. Using a VFD with a contactor in front of it or behind it. Not understanding the difference between Decel and Braking. Not understanding Dynamic Braking at all, so not properly sizing the braking resistor or selecting a cheap drive with too small of a chopper transistor. Not understanding that running a motor at low speeds for a long time also reduces the motor's ability to cool itself. Not understanding that gear/belt reduction of speed INCREASES torque, while a VFD MAINTAINS torque. Not understanding torque... I could go on and on, but my fingers are getting tired.
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Old October 10th, 2018, 09:27 PM   #15
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Muchas gracias
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