K-13 Rated Transformer schedule

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tvo

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Hi all,
I am just wondering if any of you have a schedule with feeder, MOCP, Ground and 200% Neutral conductor for the K13 Rated transformer? I try to search the forum, but can't find anything. If you have a copy, please share with me.
Thanks,
Tvo
 
I don't understand what you are asking for. Schedule? What schedule? Are you asking how to select a conductor size, for example? That would depend on the KVA rating and the primary and secondary voltages. Also, the fact that the transformer is K-rated does not change any of the things you are asking about. Can you clarify the question?
 
Hi,
I was refering to the conductor size on the secondary for the 200% neutral on the K-13 rated. How do you calculate the 200% neutral?
I read the study from Square D. The study said that the maximum theoretical neutral current is 173% of the phase conductors based on worst case condition of rectifier conduction angles of 60 degrees.
So technically, you don't just run an extra conductor in parallel to get 200% neutral. Plus you can't run parallel conductor less than 1/0.
I would just take 173% * the phase conductor size to get the 200% neutral conductor. What is your take on this?
Thanks,
TVo
 
You are making this more complicated than it is.
Simply double your neutral size.

If it is a 100 amp output then the neutral would be sized for 200 amps.
 
Yes, that's a simply way to look at it. For transformer size like 15KVA, and 30KVA, you can't run paralell conductor for the neutral since the phase conductor is #6 for 15KVA, and #2 for 30KVA. The phase conductor is less than #1/0 per NEC 310.4.
In this case the 200% Neutral for the 15KVA should be #3, and 2/0 for the 30KVA. Am I correct?
For the rest of the standard size, 45KVA and up, I can use set of 5 whatever the phase conductor is. Is it fair to say so?

Thanks,

TVo
 
For the 15 KVA, you can run a #3 neutral, and for the 30 KVA, you can run a 3/0 neutral. Those have an ampacity of twice the transformer's rating for the ungrounded conductors.
 
I should have added that either you could upsize the single conductor or parallel if over 1/0.

If you order a panel with a 200% neutral, it should come with the lugs for paralleling.
 
check neutral on neutral bar, also check for continuity between neutral and ground, OHMS should be zero. if a local handy man/ "lectrician" just "helped out". when you open the panel check all connections for tightness and visible heat damage. additionally, correct wire size on corresponding breaker. In So. Oregon most homes have panels out side as well.
 
I know what your looking for. I use to have a similar cross reference for 480-208 / 120V dry type transformers. It showed the FLA, C/B @1.25%, wire size, gnd wire size, and conduit for both primary and secondary.

I've never seen one for a transformer that needed a 200% neutral for non-linear loads.
 
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