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7 comments
Active Contributor

Join Date: Apr 2007
Posts: 20

Locked-Rotor KVA Code (Letter)

04/07/2008 12:20 PM

How do you determine the Locked-Rotor KVA Code letter designation? I am being asked by a utilty company (here in the U.S.) to provide this information.

Any help would be appreciated.

jjbadski

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Guru
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#1

Re: Locked-Rotor KVA Code (Letter)

04/07/2008 2:55 PM

Determine it? It is something that is required to be on the motor nameplate.

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Active Contributor

Join Date: Apr 2007
Posts: 20
#2

Re: Locked-Rotor KVA Code (Letter)

04/07/2008 3:07 PM

So then this is something that can't be indicated until the shop drawings are submitted for the motors?

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Guru
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#4
In reply to #2

Re: Locked-Rotor KVA Code (Letter)

04/07/2008 9:29 PM

Essentially, yes. Here is what I was talking of.

http://www.arescobuyersclub.com/nameplates.html

The kVA code letter is required to be on the nameplate. it either says "kVA Code" as in the above example, or sometimes "NEMA Code" or even just "Code", but the data must be on there for NEMA design motors.

But you technically could specify a particular code number, or a 'not to exceed" value if you are planning a project. if so, and you don't know where to start, select a motor from a manufacturer that you are confident will work, then see what their Code number is and specify it.

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Guru

Join Date: Dec 2007
Location: Cypress Calif
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#3

Re: Locked-Rotor KVA Code (Letter)

04/07/2008 7:07 PM

I'm not sure if this is what you're looking for, or if it will help you any.

http://www.engineeringtoolbox.com/locked-rotor-code-d_917.html

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Power-User

Join Date: Oct 2006
Location: Indonesia
Posts: 102
#5

Re: Locked-Rotor KVA Code (Letter)

04/07/2008 11:51 PM

NEMA table 430-7(b) outline the Locked-Rotor Code Letter.

Lock Rotor code is about ratio of kVA/hp. As you know kVA = √3 *V*I, and HP you know it as well. So, find this ratio and give to your asker, instead of code letter if you don't have NEMA table 430-7(b).

cheers

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Guru

Join Date: Nov 2006
Posts: 663
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#6

Re: Locked-Rotor KVA Code (Letter)

04/08/2008 7:56 AM

It is KVA per hp under locked rotor conditions.NEC code starts wit a to V a for example stands for 0-3.14, B for 3.15 to 3.54 these are kva per hp values.

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Anonymous Poster
#7

Re: Locked-Rotor KVA Code (Letter)

07/05/2009 2:07 AM

1) That is as per Standard NEMA, and was built starting the motor wih nominal voltage and and having bloked the rotor. As motors are built by many manufaturers and as for example a 2 HP IEM motor will have a different starting curren as a 2 HP ABB motor even if they are of the same motors class(they have different starting current because they do not have the same impendance). That is the reason a code letter has a range of values.

2) The code letter A is for small motors and so on for bigger motor B,C, D, etc.

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Abu Khansa (1); Anonymous Poster (1); jjbadski (1); JRaef (2); nesubra (1); YWROADRUNNER (1)

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