Oil Filled vs Dry Type Transformer for outdoor applicaitons

[philly]

I wanted to get some feedback on how most approach transformer types for outdoor applications with transformers used for unit sub application with MV primary and 480V secondary in the less than 5000kVA range.

I have seen some documentation that recommends 2500kVA as cut over point from dry type to oil filled but typically see oil filled in most applications outside of a few cast coil transformers used in certain outdoor applications.

I know that dry type transformers typically have a higher cost than oil filled counterparts. Downside to oil filled units is also need for oil containment and required clearances to buildings, structures for fire prevention. Is there a typical size transformer that up to that size oil containment will not be required based on FM requirement of transformer not having more than 500gallons of oil?

 

[WasGSOHM]

You seem to be looking for a formula linking
size to choice of option.

I have searched for a formula linking CCA to Ah ratings for car batteries and I found it.
Fortunately, it is a well-correlated straight-line relationship but your answer may not be.

Graph all your size data and mark each point with an O or a D.
If your eyeballs don't pick out a relationship, then "it depends."

I inherited a financial calculator, the BAII, but I don't do much finance on it.
This thing picks out the best fit formula for the data you enter and prints out the correlation [r] and just about any statistic anyone would want.

You might also look for built in routines for your spreadsheet.

 

[ron]

We use seed oil or FR3 fluid in all "oil" filled transformer applications both outdoor and indoor and you get smaller footprint, better efficiency and often cheaper price. The "oil" is low flame so no containment required, but I put it anyway to make it cleaner.
No real cutoff of size, as long as the vendor will make it.

 

[WasGSOHM]

We use seed oil or FR3 fluid in all "oil" filled transformer applications both outdoor and indoor and you get smaller footprint, better efficiency and often cheaper price. The "oil" is low flame so no containment required, but I put it anyway to make it cleaner.

The fluid is to reduce hotspots and so prolong service lifetime?

 

[MrJLH]

I wanted to get some feedback on how most approach transformer types for outdoor applications with transformers used for unit sub application with MV primary and 480V secondary in the less than 5000kVA range.

I have seen some documentation that recommends 2500kVA as cut over point from dry type to oil filled but typically see oil filled in most applications outside of a few cast coil transformers used in certain outdoor applications.

I know that dry type transformers typically have a higher cost than oil filled counterparts. Downside to oil filled units is also need for oil containment and required clearances to buildings, structures for fire prevention. Is there a typical size transformer that up to that size oil containment will not be required based on FM requirement of transformer not having more than 500gallons of oil?

To put things in to perspective, we have numerous 1500kVa MV to LV transformers in our facility. Each one of those transformers holds approximately 550 gallons. We also have numerous 13.8kV to 4.160 units at 5000kV, each transformer hold about 1500 gallons of oil.

Why is a liquid filled transformer a down side for the containment and clearances?

 

[tortuga]

philly it also depends what will the transformers be loaded to? And what are the load periods? intermittent / continuous loads ?
Do you expect allot of harmonics etc?

 

[WasGSOHM]

I wanted to get some feedback on how most approach transformer types for outdoor applications with transformers used for unit sub application with MV primary and 480V secondary in the less than 5000kVA range.

I have seen some documentation that recommends 2500kVA as cut over point from dry type to oil filled but typically see oil filled in most applications outside of a few cast coil transformers used in certain outdoor applications.

I know that dry type transformers typically have a higher cost than oil filled counterparts. Downside to oil filled units is also need for oil containment and required clearances to buildings, structures for fire prevention. Is there a typical size transformer that up to that size oil containment will not be required based on FM requirement of transformer not having more than 500gallons of oil?

Gimme what data you already have and I'll punch it into my calculator!

I can use the practice in interpreting statistics.

BTW, there really is a "27 club" and 85 years might be a built-in lifespan for people.

 

[ron]

The fluid is to reduce hotspots and so prolong service lifetime?

Fluid is the cooling method as it circulates around and out to the radiator fins rather than just air radiating