7.2 kV Distribution Shunt Reactors
7.2 kV Distribution Shunt Reactors
(OP)
We are working with a client who is experiencing failures of their single phase air core shunt reactors applied at 7.2 kV. The system consists of extremely long, lightly loaded, underground cable runs along railway corridors. Reactors fairly regularly burn up without necessarily causing an immediate short circuit on the system. Weather conditions do not seem to be a factor. Could there be a problem with resonance in this case? The reactors are switched manually. They are installed on wooden stands and suitable grounding may also be of concern. I have seen mention of adding surge arresters at the reactor terminals in this type of application, however there are arresters are installed in the line side of the isolation switches. Photo is attached of failed reactor.






RE: 7.2 kV Distribution Shunt Reactors
The cables are operated at 7.2 kV phase to ground, correct?
How often are the reactors connected or what is the spacing between reactors?
What is the ampere rating of the reactors? Do you know the kvar or uH rating?
What cable size are you using? Presumably this is 15 kV cable, correct?
Once you answer some of these, we can see if resonance is a possibility or not.
RE: 7.2 kV Distribution Shunt Reactors
RE: 7.2 kV Distribution Shunt Reactors
KMH1
What are the dimensions of the reactor? You mentioned a single phase reactor, but I see (3) reactors in the picture. It looks like a (2) layer design reactor. I assume the the layers are in parallel not series. It could be that the volts per turn are too high. Also shunt reactors are subjected to vibration type forces so the turns must be constrained.
Good luck
RE: 7.2 kV Distribution Shunt Reactors
RE: 7.2 kV Distribution Shunt Reactors
Were the failures associated with the 11 mi or 20 mi run? Or both?
If you can get a current reading at the reactor end and see if you're pulling more than 20 A, that would be worth doing. Or set a small distribution transformer and check the voltage.
Had you checked how much charging current was drawn at the source end before you connected the reactors?
I don't think too much about the vibration theory. If they had a magnetic core, I might buy that, but not with an air core.
RE: 7.2 kV Distribution Shunt Reactors
If I knew the dimensions It would help
RE: 7.2 kV Distribution Shunt Reactors