30kva 3phase step up transformer

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Pratch

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I am running power for a sasso k600 extreme Cnc saw and it comes with a 30kva 3phase step up transformer.the saw requires 400volts, the transformers primary side is 230 volts and secondary side is 400 volts. The normal running amps for saw is 80 and a max of 125.so my ? Is what size wire do I need to run to the primary side of transformer and what amp breaker. And then what size wire coming of the secondary side going to saw? I'd appreciate any help
 
Pratch said:
I am running power for a sasso k600 extreme Cnc saw and it comes with a 30kva 3phase step up transformer.the saw requires 400volts, the transformers primary side is 230 volts and secondary side is 400 volts. The normal running amps for saw is 80 and a max of 125.so my ? Is what size wire do I need to run to the primary side of transformer and what amp breaker. And then what size wire coming of the secondary side going to saw? I'd appreciate any help
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30kVA at 230V is about 75A.
30kVA at 400V s about 43A.

Is the 80A for an intermittent duty rather than the NRL?
 
Welcome to the forum. Looked up that saw; it's a beast!

https://www.youtube.com/watch?v=F7z-q2AG38A

Anyway, look to article 430 for sizing your conductors for the motor. This article may be of some help:

http://www.ecmweb.com/design/motor-calculations-part-1-motors-and-branch-circuit-conductors

For the transformer primary and overcurrent protection, see these two articles:

http://www.ecmweb.com/code-basics/transformer-secondary-conductors

https://www.ecmag.com/section/codes-standards/sizing-conductors-part-xxvi

It's too late and I dont do motor/xfmr calcs enough to give you hard numbers.
 
This appears to be a duplicate thread. I posted a response to same question already.

New member (welcome) your first few posts need to be approved by a moderator before they will show up so be patient, they just want to make sure you are legitimate member and not a robot.
 
I closed the duplicate thread.

Where did the transformer requirement come from? In that video, I see an AC induction saw arbor motor. 400V implies that motor is designed for 400V 50Hz. If you give it 400V 60Hz here, you may damage the motor and the blade because of the change in speed and V/Hz ratio. We don't know how the entire machine is built however, i.e. Maybe there is a VFD on that arbor motor. So if the saw mfr is who told you to use a 30kVA transformer, they likely know more about how it needs to be powered. But if this is coming from someone else as an assumption, I would be very suspicious of it.
 
400 vac at 80-125 A (avg ~100 A)
I'ld size for 125

primary 400/230 x 125 = 220 A, CB 250

the xfmr is likely an auto xfmr (400 - 230) x 100 x sqrt3 ~ 30 kva

seems like alot ~ 75 hp
 
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Besoeker said:
We are told that the transformer has a primary and a secondary which would mean double wound.
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We didn't get solid confirmation of what kind of transformer it is, just that it has 230 in and 400 out.

An autotransformer may explain why only 30 kVA rating when it appears the machine driven has even higher rating.
 
Besoeker said:
How many separate windings are shown?
Which one is the primary winding and which the secondary?
Your diagram shows input and output voltages derived from the same winding.
Click to expand...

it also labels them primary and secondary
more of naming convention for power in vs power out
they share a common winding
you said primary/secondary always denotes 2 windings: it does not
a 2 windind xfmr can be configured as an autoxfmr


The input side is called the primary side of the transformer, because this is where the main electrical power to be changed is connected.

The output side is called the secondary side of the transformer. This is where the electrical power is sent to the load.

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/Auto_Transformer.pdf
An auto transformer is the one which consists of a single winding, part of which acts as the primary winding of the transformer, and some part of which acts the secondary winding, which can be varied by switching between the contacts of the transformer.
 
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Besoeker said:
I didn't.
Let's leave it at that.
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you implied I was wrong postulating it may be an AT
you feel compelled to correct me
because the op used the terms primary:secondary you said it implies 2 windings

my post showing an AT labelled prim/sec came after that exchange
obviously with a typo "does" vs "doesn't" (obvious since since it showed a single winding labelled prim:sec)

quote_icon.png
Originally Posted by Besoeker
We are told that the transformer has a primary and a secondary which would mean double wound.

http://www.eaton.com.co/ecm/idcplg?...veAs=0&Rendition=Primary&dDocName=TB00900004E
Autotransformer: A transformer in which part of the winding is common to both the primary and the secondary circuits.


WE weren't that
now we can 'leave it'




 
Ingenieur said:
you implied I was wrong postulating it may be an AT
you feel compelled to correct me
because the op used the terms primary:secondary you said it implies 2 windings

my post showing an AT labelled prim/sec came after that exchange
obviously with a typo "does" vs "doesn't" (obvious since since it showed a single winding labelled prim:sec)

quote_icon.png
Originally Posted by Besoeker
We are told that the transformer has a primary and a secondary which would mean double wound.

http://www.eaton.com.co/ecm/idcplg?...veAs=0&Rendition=Primary&dDocName=TB00900004E
Autotransformer: A transformer in which part of the winding is common to both the primary and the secondary circuits.


WE weren't that
now we can 'leave it'
Click to expand...
See post #12.
 
Ingenieur said:
see post 7
Click to expand...

Besoeker said:
See post #12.
Click to expand...

:roll:

Besoeker never wrote the word "always". and neither post helps the OP in any way, shape, or form.

Anyway, Sasso is an American company:

http://www.sassousa.com/

calling them to get electrical specs should be pretty easy. The main motor is 18-25HP (Extreme has the 25HP); a 30kva xfmr can handle that fine. It seems to me to be highly unlikely here you have a Euro-spec (230/400 50Hz) saw in the US when the company is based in the US.

A call Tuesday morning should answer any questions you have.

eta: did a *bit* of math/research. I think the 25HP saw would draw ~34A @ 400V. The 80A/125A is more than likely primary side wire ampacity and breaker size, respectively.
 
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he did state prim/sec means 2 winding so excludes the possibility of an AT

80-125 A ~ 55-85 kva so a 75 or larger xfmr
op said 30 kva

the data on the machine says power is 18 kw (at least what I could find)
so 20-25 hp
we need more info

isn't sasso an Italian company with a US subsidiary or distributer?
 
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Ingenieur said:
he did state prim/sec means 2 winding so excludes the possibility of an AT

80-125 A ~ 55-85 kva so a 75 or larger xfmr
op said 30 kva

the data on the machine says power is 13 kw (at least what I could find)
we need more info

isn't sasso an Italian company with a US subsidiary or distributer?
Click to expand...

probably is; I found another link in Italian first / English second. still, the American distributor should be able to answer questions re: electrical requirement.

A 30kVA 3ph xfmr that has 230V on the primary side is 75.3A on the primary side, regardless of the secondary voltage. 75.3 x 1.732 x
230V = 30,000.

Why are you calculating the 80-125A at 400V vs 230V? What 25HP motor draws 80A @ 400V? Also, why would you need larger than a 30kVA xfmr when, according to you, "data on the machine says power is 13 kw"?
 
Ingenieur said:
he did state prim/sec means 2 winding so excludes the possibility of an AT

80-125 A ~ 55-85 kva so a 75 or larger xfmr
op said 30 kva

the data on the machine says power is 18 kw (at least what I could find)
so 20-25 hp
we need more info

isn't sasso an Italian company with a US subsidiary or distributer?
Click to expand...
The machine stated by the op has a 25 hp motor rated for 400 volts. Wouldn't that be about 30 kw? Wouldn't that make the 230 volt primary a little more than 75 amps? If the machine has built in ocp(which it probably does) wouldn't that allow 125 amp ocp for the primary?
 
JFletcher said:
probably is; I found another link in Italian first / English second. still, the American distributor should be able to answer questions re: electrical requirement.

A 30kVA 3ph xfmr that has 230V on the primary side is 75.3A on the primary side, regardless of the secondary voltage. 75.3 x 1.732 x
230V = 30,000.

Why are you calculating the 80-125A at 400V vs 230V? What 25HP motor draws 80A @ 400V? Also, why would you need larger than a 30kVA xfmr when, according to you, "data on the machine says power is 13 kw"?
Click to expand...

op said the machine (saw) draws 80-125 A and it is 400 vac
his ??? how to size the prim/230 side
if he knew it drew 80-125 on the prim why ask?

I did say the power seemed high ~ 100 A at 400 vac ~ 75 hp
I did not find the kw til afterwards and since it was in Italian was not sure what it represented

edited
Pratch said:
the saw requires 400volts
The normal running amps for saw is 80 and a max of 125
so my ? Is what size wire do I need to run to the primary
Click to expand...
 
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