Pit volume of single phase auto-transformer.

[SauravWest]

Dear sirs,

A literature reads,
"The oil collection pit thus formed shall have a void volume equal to 200% volume for 220
kV & above and 130% for 132 kV & below of total oil in the Transformer /Reactor."

Does this mean that the pit should hold twice the volume of oil of single transformer?

regards,

 

[prc]

The norm varies from country to country. I have never noticed more than 100 % oil volume. Usually it is limited to 50 % with a common pit of 100 % connected to all transformers.

 

[cuky2000]

The regulation in many countries require sized the transformer oil containment to hold at least 100 percent of the oil contained in the largest single piece of equipment plus a reasonable allowance for precipitation.

[sub]NOTES:
1) It is common to fill the pit with rock for fire quenching and the net volume for oil spill is determine by the voids between stones and empty pipe added. Also some foundation are designed with piers instead a monolithic foundation to minimize the pit size if the transformer core is braced accordingly.
2) In many places, the regulation allow equipment pits be provided with a means to drain rainwater from the enclosures without possible loss of oil. This may be done by using polymer agents, manual valves, or acceptable mean.
3) it is a good engineering an environment practice to include the preparation and implementation of an oil spill prevention, control, and countermeasure and additional precaution if the facilities is in the proximity to navigable waters.[/sub]

 

[bacon4life]

I have heard of using 110% or 125% of the oil volume, where the extra percentage accounts for precipitation. Be aware that for large slabs, the 24 hour precipitation value can require more than a 25% margin. Another consideration is water and/or foam from firefighting efforts.