Motor "type"

[Tmoose]

We are replacing some 75 HP 460 volt 900 rpm ODP motors from the 1970s. Frame 444TS.

The old probably original name plate also includes " Type K ".
As best I can tell Type K means 8.0 to 8.99 KVA per HP with locked rotor or somesuch .

I guess this is beyond, or in addition to the "Design" B which identifies a motor’s heavy load starting capability. “Design” classification ( A, B, C, or D) in the motor’s specifications.

It seems like modern motors do not mention "Type".
Is "Type" obsolete?

It appears Most modern 444TS motors are 100 HP or more.
I guess we'll just have to keep searching.

 

[electricpete]

As best I can tell Type K means 8.0 to 8.99 KVA per HP with locked rotor or somesuch .

I don't think so. KVA per HP is associated with KVA code. Your nameplate says "code" G. So I assume it's kva code G (5.6 - 6.29 kva/hp)

I guess this is beyond, or in addition to the "Design" B which identifies a motor’s heavy load starting capability. “Design” classification ( A, B, C, or D) in the motor’s specifications.

Yes, KVA code (A thru V) and NEMA design letter (A/B/C/D/E, but mostly B) are different things.

And Type K seems to be something else entirely...

=====================================
(2B)+(2B)' ?

 

[electricpete]

Here's what googling found about "type"

https://www.elongo.com/pdfs/MotorNameplate990519.pdf

Type
NEMA MG 1 requires manufacturer's type, but there is no industry standard regarding what this is. Some manufacturers use "Type" to define the motor as single or polyphase, single or multispeed, or even by type of construction. Type is of little use in defining a motor for replacement purposes unless you also note the specific motor manufacturer. [emphasis added by electricpete]

=====================================
(2B)+(2B)' ?

 

[electricpete]

We are replacing some 75 HP 460 volt 900 rpm ODP motors from the 1970s. Frame 444TS.

You might be able to find it if you drop the odp. You typically don't need it for interchangeability (unless your application has some unique requirements, possibly clearance on the ODE)
Modern motors fit the same stuff into a smaller frame, all else being equal. . TEFC typically takes a bigger frame than odp, all else being equal.
Put them together: Modern TEFC often come in the same frame size as older ODP of similar ratings.

Here's two that match 444T but not 444TS
[ul]
[li]

https://www.baldor.com/catalog/ECP4419T-4

75HP, 890RPM, 3PH, 60HZ, 444T, TEFC, F1 460VAC[/li]
[li]

https://www.electricmotorsforless.c...0-rpm-3-phase-230460-PE444T-75-8C-_p_860.html

[/li]
[/ul]

Maybe a 444T can be converted to 444TS by cutting off the end of the shaft? I'm not sure.

=====================================
(2B)+(2B)' ?

 

[Tmoose]

once again, thanks e-pete.

I think the TS shaft is inches shorter and about an inch smaller Ø too.

I am amazed -
1 - these ODP motors have survived so well in a coal fired power plant from the 1970s.
2 - The customer is asking for "replacement in kind."For decades TEFC has been the usual minimum to keep coal dust and washdown water out of the windings.

 

[electricpete]

I think the TS shaft is inches shorter and about an inch smaller Ø too.

Yup, you're right I forgot about the smaller shaft diameter. So it would be an even trickier machining job to cut the length and trim the diameter. Not an attractive option except as a last resort.

I am amazed...

I agree, I would have expected odp motors installed in a coal plant environment during the 70's to have died long ago.

=====================================
(2B)+(2B)' ?

 

[jraef]

From the GE Motor Selection Guide:

2. Electrical Type Letters
a. Polyphase:
K NEMA designs A & B
KAF Adjustable frequency
KE NEMA design A & B complying with Federal Energy Act
KG NEMA design C
KGS NEMA design C Energy Saver
KL Hydraulic elevator
KOF Oil well pumping
KR NEMA design D
KS NEMA design A & B Energy Saver
KY Special characteristics

So "Type K" just means it is the most basic of plain-Jane motors.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[DAVIDSTECKER]

A 900 RPM motor is not typically an off the shelf motor and most likely is going to be a special order, so getting the shaft required isn't going to be any more of a problem than getting a one-off motor.
ABB/Baldor is really good about these special orders.
Another is Reuland.
That said, don't be surprised when they give you a 20 week lead time.

 

[Tmoose]

thanks all !

Dan T

 

[LionelHutz]

Ya, they might take a 1800rpm motor and re-core it for 900rpm. Just hope they end up with a good rotor-stator slot combination. Ran into an issue with 2 Baldor 900rpm motors not that long ago. They wouldn't start right. Then their stupidity started.

 

[Gr8blu]

Tmoose: "Type" means exactly what it says - the TYPE of machine. For example: there are two types of induction machines (squirrel cage and wound rotor). There is sychronous (both traditional and permanent magent). There is direct current. There is switched reluctance. There is linear. . . . see the trend?

For your specific case - most North American manufacturers used the designation "K" (or sometimes "KS") to indicate the machine was a squirrel cage induction design with (usually) a NEMA B torque profile for acceleration.

Converting energy to motion for more than half a century

 

[electricpete]

>Ya, they might take a 1800rpm motor and re-core it for 900rpm. Just hope they end up with a good rotor-stator slot combination. Ran into an issue with 2 Baldor 900rpm motors not that long ago. They wouldn't start right. Then their stupidity started.

just to build on that for op's benefit.

i think rewind would be a more common option than recore. but you're right there are certain combinations of stator slots, rotor slots, and poles that are bad (so original motor might be fine but changing the pole number could move you to bad combination).

Integral slot windings are more common than fractional slot windings (and far less noisy in my experience) so if you start with a 4-pole integral slot winding that has an even number of slots per pole-phase group, then you could still rewind to end up with an 8 pole winding that is also an integral slot winding (but again doesn't necessarily avoid problematic stator/rotor/pole number combinations).

There may be other pole number windings that (2 pole or 6 pole) that could be successfuly rewound to 8 pole. If you're going to rewind, then the number of stator slots is more relevant than original pole number. Unfortunately number of stator slots (and rotor bars for that matter) is rarely to be found in catalogue info.

Recore is a more expensive option than rewind, but it gives you flexibility to change the number of stator slots (to avoid problematic stator/rotor/pole number combinations and also to achieve integral slot winding which is preferred over fractional slot winding, at least in my book).

tldr - rewinding a 444TS 2 or 4 or 6 pole motor may be a good option. you'll need involvement of a knowledeable motor repair shop.


=====================================
(2B)+(2B)' ?

 

[petronila]

Tmoose,

The Type is a designation that belongs to the manufacturer itself for its own production control and it is not a factor to replace a motor. Althoug the name plate is showing all electric and mechanical parameters of the old motor there are at least two important considerations for choosing the new motor:

1. For avoiding mechanical mounting issues choose the same frame then the foot mounting holes, output shaft diameter and lenght, etc. are gonna match.

2. For avoiding electrical issues, choose same power output, voltage, poles and letter code, letter code is important for granting the motor will develop the same inrush current during the starting and will not trip breakers or in the worst escenario choosing a motor (with a lower Inrush current)that might not drive the attached load.

I will conduct a previous study using a motor analyzer in order to determine if your actual motors are oversized and determine if you can replace with a lower rated motors. Also I will take account the application because V belt loads often requires a roller bearings in the DE. It is possible too that these old motors may be replaced with motors driven with VFD. Also consider if you have vertical mounting too

I believe above considerations may be useful. I will not replace one motor only using the nameplate information.

Best Regards

Petronila