Transformer power factor under vacuum

[NBatson]

Power factor testing an empty liquid-filled transformer?

Attachment 383

Doble Power Factor Test. Obviously not the recommended way but it can be done under reduced voltages.

Delta windings

161kv+ -10kv
115-138 -5kv
34-69 -2kv
12-25 -1kv
-12 .5kv

wye windings

12kv+ -1kv
below12kv -.5kv

[SecondGen]

Doble Power Factor Test. Obviously not the recommended way but it can be done under reduced voltages.

This is interesting, I don't think we've ever done it at my shop. What is the main purpose of testing without oil?

[NBatson]

This is interesting, I don't think we've ever done it at my shop. What is the main purpose of testing without oil?

There are different scenarios but an example would be:

If you pull the core and coils you could test those separately to see if the root cause was in the core and windings or if its insulation parts in the tank.

Another example could be if your testing the 480v secondary side and your suspecting faulty bushing its hard to guard off that little bushing. You could drain and test it strait to the coil to place the blame on the bushing or to rule it out.

We had the opportunity to take the doble training class and it was super full of information. I'm still new to the testing field so I really enjoy stuff like that.

[SecondGen]

There are different scenarios but an example would be:

If you pull the core and coils you could test those separately to see if the root cause was in the core and windings or if its insulation parts in the tank.

Another example could be if your testing the 480v secondary side and your suspecting faulty bushing its hard to guard off that little bushing. You could drain and test it strait to the coil to place the blame on the bushing or to rule it out.

We had the opportunity to take the doble training class and it was super full of information. I'm still new to the testing field so I really enjoy stuff like that.

That makes sense, I figured it was most likely used in diagnostics or specialized applications. Have you ever done it that way in the field? Just curious about what kind of numbers you get.