# sizing transformer for loadbanking



## Generator51 (May 4, 2012)

I have a 2megawatt 480 load bank used for generator testing. I need to size a transformer so I can test 4160 volt. The normal way would use a 2500 kva transformer. I plan to make it portable. I need to get the weight down as much as posiblle. I have tested using a 2500 kva and there is no temp rise with the transformer. The duty cycle will be no more than 5 hours. my thought would be down size and lose weight to make it more portable. What are your thoughts. Thanks


----------



## bobelectric (Feb 24, 2007)

Generator51 said:


> I have a 2megawatt 480 load bank used for generator testing. I need to size a transformer so I can test 4160 volt. The normal way would use a 2500 kva transformer. I plan to make it portable. I need to get the weight down as much as posiblle. I have tested using a 2500 kva and there is no temp rise with the transformer. The duty cycle will be no more than 5 hours. my thought would be down size and lose weight to make it more portable. What are your thoughts. Thanks


I would sub it out,rather than getting into all that cabling and terminations


----------



## Generator51 (May 4, 2012)

I am the sub the is doing this work. The 4160 side does not have that much wiring. I just don't think you need a full size transformer for just a short duty cycle Thanks


----------



## BBQ (Nov 16, 2010)

Generator51 said:


> I am the sub the is doing this work. The 4160 side does not have that much wiring. I just don't think you need a full size transformer for just a short duty cycle Thanks


I think if you contact a major transformer manufacturer they could help you with this. 

Power companies regular 'overload' transformers knowing that the length of the overload will not overheat the transformer.

You could also ask about using forced cooling with fans or maybe even water.


----------



## brian john (Mar 11, 2007)

bobelectric said:


> I would sub it out,rather than getting into all that cabling and terminations


Bob, all that is part of doing load test.


----------



## brian john (Mar 11, 2007)

Are you using a dry type or oiled filled?


----------



## Generator51 (May 4, 2012)

I would like to use a oil filled. I will not use to much, so it will be easer to store. I am open to anything right now. Some of the thoughts I have are the busing in the transformer. Will they carry the short large load. I know transformers can overload. I haven't a lot of experance over loading transformers. Fan cooling is more of a long term fix. I would like to find a used transformer. Cost savings would be nice for the small amount of time I will use it. Thats why I'm here, to see if someone has some backround in this area.


----------



## brian john (Mar 11, 2007)

First what are your typical load steps and duration at each load. In a 5 hour load test you are at 100% what 1-2 hours?

http://www.usbr.gov/power/data/fist/fist1_5/vol1-5.pdf


----------



## Generator51 (May 4, 2012)

Load Test starts 25% one hour,50% one hour. 75% one hour, 100% two hours. at 100% it pulls a little over 2400 amps. 480 volts


----------



## MDShunk (Jan 7, 2007)

I'm thinking you're going to have some transportation issues to tend with if you use an oil-filled transformer. Placarding, containment, hazmat endorsement for driver, etc.


----------



## Big John (May 23, 2010)

That's my thinking. I would suggest a dry-type, but you've gotta have a reasonably conditioned place to store it, or else get an encapsulated style. You can't leave the thing sitting in a yard somewhere.

-John


----------



## brian john (Mar 11, 2007)

Big John said:


> That's my thinking. I would suggest a dry-type, but you've gotta have a reasonably conditioned place to store it, or else get an encapsulated style. _You can't leave the thing sitting in a yard somewhere._
> 
> -John


 
I have seen it done time and again. THOUGH NOT RECOMMENDED

Maybe two dry types on two trailers parallel them, easier to transport.


----------



## Generator51 (May 4, 2012)

I ideal way is two trailers. I'am tring to keep travel time down. I live in central California. I travel south as far as the Mexican border, north to the Calif border. You can see road time needs to be kept down. What I need to Know is how small a Transformer I can use and make it work. Like will a 1200 Kva work without damage to it. Due to duty cycle


----------

