Transformer For Robot Install

[Bob49]

We are installing a robot with the following specs. 480 volts. 3 phase. Input power source capacity 12kva. Average consumption 2.5 kw. The. Robot has a 20 amp breaker on it. We are looking at 240D/480Y 15kva 18 amp transformer. Our installer said we could use this or go with a 36 amp transformer. Thanks for any thoughts on this.

 

[Jraef]

The robot mfr says you need at least 12kVA, you are wanting to use 15kVA. That fits the bill. 36A means a 30kVA transformer, overkill for that requirement. He is likely thinking that the 20A breaker would determine the transformer size, that would not be a wise use of your money. Would it work? Of course, but it would cost you more for no good reason (unless you might some day add another robot there).

 

[Bob49]

The robot mfr says you need at least 12kVA, you are wanting to use 15kVA. That fits the bill. 36A means a 30kVA transformer, overkill for that requirement. He is likely thinking that the 20A breaker would determine the transformer size, that would not be a wise use of your money. Would it work? Of course, but it would cost you more for no good reason (unless you might some day add another robot there).

Thank you Jraef for the very helpful reply. So going with the 3 phase 12 kva 240D/480Y, and researching the forum, it looks like we will need a 40 amp breaker and #8 conductors on the primary and a 20 amp with #12 on the secondary. Does this look correct ? Thank you.

 

[augie47]

Been a while since Jraef has posted so I'll take the liberty of saying you are correct.
(IF he happens to reply later, listen to him as hes a ton smarter than I am )