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Transformer amps


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Hi guys im doing m/c installation. We bought the m/c from korea. In malaysia we using 415v but the m/c need 3 phase with 220v so i need to use transformer. I have 2 unit 5kva transformer. The sec amp is 7 and the pri amp is 14amp. Now i want to ask u all, the m/c circuit breaker is 30amp. So can i use 1 transformer to run 2 m/c????????. Plz guide me.

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I am guessing that ‘M/C’ means Motor Control.
It also sounds like you are dealing with 3 phase
Power so the motor control you are talking about
Must be a fairly hefty one.

What concerns me is not the 30A rating of
The controller but the current demand of the
Motors you plan on using.  At 220V with 7A
You can expect around 3-4 Hp or 1500W
(Note: I just rounded, I did not compensate for
3 phases or power balancing)

If the motor is under that range then you should not have a problem
The transformer can only provide up to 14 amps max, and if the
Motors only draw 14A max then the 30 rating of the controller
Should be a blessing as it can easily handle the load.

The one thing that you did not make clear is the type of
Transformer you have.  I am guessing you have a step down
Transformer to drop from 415 down to 220.  I have not encountered
A large number of 3phase transformers that make such a small
Step. Usually I see 13,800V down to 220.  I was worried that you
Had a single phase transformer and you wanted to get 3 phase
Power from it. 

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Thanks for you reply Theatronics. What you said is true, this machine have 3 main motor. 1 is 2hp motor and 2 more is servo motor. I think the hp is less then 0.5 because its small motor. Now i have 2 unit of machine that bought from korea. The power supplt is 220v 3 phase. I have 2 unit stepdown transformer. From 415v 3 phase down to 220v 3 phase. Now i just want get idea from u all is't suitable me to use 1 unit transformer to run 2 unit of machine??? and can someone explain me how to culcalate kva to amp????? for example 5kVa transformer can use for homy many amp machine or motor?????????

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  • 2 weeks later...

the circuit you connect to the transformer draws its own current according to its resistance .
but this 15 A which u are talking about is the transformer rating.
2 coils connected in parallel!!!!
god knows what interferences come !
and how much current it drws.moreover always keep a safety factor!
so better run only one M/C on it.

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