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Reference: ISH2017_198

Type:
ISH Collection
Title:

Flashover rate of vertically-arranged 6.6 kv power distribution line

 

Abstracts

For the effective insulation design of 6.6kV overhead power distribution line (OPDL), it is important to estimate the flashover rate accurately. Up to now, the flashover rate has been investigated for the horizontally configured OPDLs. In this paper, the flashover rate for the vertically configured is studied. Since the non-grounded neutral system is used in the Japanese power distribution line, flashover at a single phase does not result in the outage. Therefore, we calculate the flashover rate as the rate of flashover at more than one phase conductor. When the first flashover occurred, the flashover phase conductor plays a role similar to the overhead ground wire (OHGW) in the sense that the conductor provides a path to the lightning current and mitigates the insulator voltage at other conductors due to the induction of the voltage on other conductors by the coupling. Therefore the relative location of the OHGW and the firstly flashover phase conductor is important in the discussion of the flashover rate. The flashover rate of the vertically configured OPDL associated with negative first strokes decreased to 90-91% of the horizontally configured line on condition that the height difference between the OHGW and the top phase conductor is the same. As for subsequent strokes, the flashover rate of the vertically configured OPDL decreased to 92-93% of horizontally configured ones. Furthermore, the authors evaluated the influence of the unbalanced insulation strength of the insulators dependent on the conductor location on the flashover rate. When the insulation strength of the low or the middle phase conductor is reduced, the flashover rate of the vertically-configured line becomes low compared with the rate for the horizontallyconfigured line. On the contrary, the flashover rate of the vertically-configured line becomes high compared with the rate of the horizontally configured line when the insulation strength of the insulators at the upper phase is reduced. In general, the closer the distance between the OHGW and the phase conductors, the less the flashover rate. In the case of the horizontal configuration the shielding angle should be taken into account in reducing the distance between the OHGW and the phase wires. However, in the vertical configuration, the shielding angle is not influenced by the reduction of the distance. This is one advantage of the vertical configuration in the discussion of the lightning protection.
 

File Size: 317,9 KB

Pages NB: 6

Year: 2017

 
 
 
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