27kV Surge Arrester Blown out CAUSING PLANT SHUTDOWN

[PQ]

Hi, can someone explain to me this phenomena. We are connected to a 34.5kV Overhead T/L serving as our incoming power, distributed in 3-1MVA transformer, one in each 3 building. For the past years we haven't encountered surge arrester to blown out (fail). Last week during heavy rains one of our 27kV surge arrester blown out putting the whole plant in total shutdown because the power fuse in L1, L2, were busted due to this event. What whould be the possible cause of the surge arrester failure? Why whould the Line 1 fuse be busted considering the surge arrester is connected to line 2, we inspected the lead and ground wire of this arrester to check if it accidentally touches the structure or other phase to create such event. But there is no sign of L-G or L-L fault. We also check with our wheather dept. if there is a lightning that day but there is none.

 

[jghrist]

One of our municipal electric utility clients has had problems with polymer MOV arresters failing on their 25 kV system. Talks with two manufacturers have revealed that there were manufacturing problems with early designs. One manufacturer had problems with moisture getting into the arresters. One manufacturer had problems with a threading problem that created aluminum powder, causing tracking.

You should contact the manufacturer of the arresters.

How is the power distributed to the three transformers from the incoming T/L? If it is by cable, then the blowing of one fuse may have caused a ferroresonant condition on the other phases.

 

[PQ]

jghrist,

Thanks, but the T/L is a Overhead one using ACSR cables. regarding the arresters we have the same brand in our plant but the other have no problem at all.