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Our Roanoke plant successfully tested a unit at 650 kV impulse voltage (BIL) for a reputable energy management company based in Texas. The unit was rated 15/20/25//28 MVA, 138 kV with LTC.


What is the significance of this test?

We interviewed Parminder Panesar, Technical Manager at the Roanoke plant:
Parminder Headshot

Q:Parminder, what is special about this 650-kV impulse test?

Parminder: Please note that 138 kV is the most popular primary voltage in the US and the typical BIL associated with this voltage is 550 kV. Some customers, however, specify 650 kV BIL for this voltage class. Obviously, we have the design & manufacturing capability for 650 kV BIL but our Roanoke plant had a limitation in our impulse test equipment of 550 kV BIL. This would require us to move such units to other plants, such as Pocatello or Rincon – thus preventing us from leveraging our Roanoke plant for customers located in the Northeast.

Now we can design, manufacture and test 650 kV BIL units at Roanoke thus giving us more capacity and flexibility to meet our customer’s needs.

Q:How did you manage to upgrade the capability to 650 kV BIL?

Parminder: We decided that the best way to upgrade the system was to replace the old one. The new system now has 30% more capacity than the old test set so we now have 1000kV capability to meet the 650BIL test.

Q: What is the logic behind installing the new test set?

Parminder: I would give two reasons:

  1. Ten 100kV – capacitor section test set will give us some redundancy for this critical unit
  2. A Strategic opportunity to extend the voltage range at Roanoke


Top BIL Rating for plants
Current Top BIL ranges of our four plants.

This expanded offering continues to demonstrate our commitment and progress in power transformer development.

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