3-phase 400V supply to control a 240V motor

[Michielj]

Hello,

I have a machine with a supply voltage of 230V single phase. The motor speed is contolled by 1 scr which is placed in the phase.(neutral directly to the motor). Cause the machine needs a 70amp fuse I want to convert is to a 3phase 400V supply. Cause I have to convert more of these machines it need to be as simple as possible, I can't change the motor and a transformator is too big to place into the machine. How can I change the motor control?

 

[waross]

Well, you could install a 3 pole, 70 amp breaker and run three machines connected line to neutral off of a 230;400 volt system.
Nowhere else to go without a transformer or changing or rewinding the motor.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

It depends. If this is a so-called "universal motor", that is a motor with a commutator and brushes, you could run it off a rectifier being fed from a three-phase grid. If it is a single-phase induction motor, you are pretty stuck with what you have.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[waross]

Is the 70 amp fuse required for the motor or for the whole machine? What is the machine? From the information you have given, we assume that the motor needs a 70 amp fuse. Is this correct?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[7anoter4]

Hi Michielj
I guess your motor is a DC motor of 10-15 kw 230 V dc supplied through a SCR controller. You may supply this motor from a three phase source:see the attachment
If is a DC motor
See

http://shek.en.alibaba.com/product/...r_High_Power_SCR_DC_Power_Supply_WWL_SS_.html

http://www.appliedps.com/newweb/Datasheets/AP-1950/AP-1950.htm

But if is an induction motor then see:

http://www.hubbell-icd.com/icd/acdc/files/4924C Catalog.pdf

Best Regards

 

[Michielj]

First of all thanks for the reactions,

The 70amp fuse is needed for the whole machine, but the main part of the drawn current is needed for the motor(s), which are 7 groups of 2 in serie 110V AC motrs. Te rest is just a little power supply for some pcb's and a litlle LCD display. Then SCR is placed in the feed cable towards a box at the back of the machine where the wiring is made to the motors. Changing the wiring is possible if no other option is possible, but first like to get an idea of the 'other' solutions.