Re: [TCML] VFD motor

[sparktron01@xxxxxxxxxxx]

One additional comment:

Early in my career when darlington transistors had just become
widely available in VFD's (@ 230VAC) I worked on a 5HP application
where the input 480 was reduced to 240 and a second output
transformer elevated voltage back to VF,VV 480 to drive 3ph motor.
The input transformer was SMOKING (at least 20-30deg C hotter)
then the output transformer.  Input THD from bridge rectifier
(no input reactor) and third order harmonics were saturating
input transformer, where the output unit was within ratings...
So BE CAREFUL when using transformers OR motors with
VFD's.  Another tid-bit, don't run motors less then 30-40%
of baseline speed nominal WITHOUT supplemental cooling;
you WILL eventually burn the motor up.  Ask me how I know...  ;^D

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA


 -------------- Original message ----------------------
From: ashumate3@xxxxxxx
> You have to remember that VFD's convert the incoming AC to a DC bus. The DC  
> is the processed back to variable AC. The larger Frequency drives have 
> internal  monitors to assure all three phases coming in. This needs to be 
> disabled. 
> Now in  terms of using it for a none rotating application such as a transformer.
>  
> Transformers are usually design around an operating frequency - i.e. 25,  50, 
> 60, 500 cycles. As long as your transformer is designed around 60 cycles you  
> can lock you drive in at 60 cycles. This can usually vary +/- 10 for  
> transformers. No manufacture will recommend this application because that is not  
> what their drives are for, but what you do with it after you buy it is up to  
> you.
>  
> Al Shumate
>  
>  
> In a message dated 1/22/2009 11:14:15 P.M. Eastern Standard Time,  
> stm800@xxxxxxxxxxx writes:
> 
> http://www.kbelectronics.com/
> 
> 
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