Pin type insulator, diagram,advantages, disadvantages

Pin type insulator

Pin type insulator diagram
Pin type insulator diagram 

Pin type insulator consists of single or multiple shells that mounted on the spindle to be fixed to the cross arm of the tower. Multiple shells are provided to obtain sufficient length of leakage path so that flash overvoltage between conductor and pin type insulator is increased. 

The design of shells is made such that if the uppermost shell gets wet due to raining, the lower shells are dry and provide sufficient leakage resistance.

In pin type overhead line insulator, power conductor passed through the groove at the top of the insulator.

Pin type insulator is used for transmission and distribution of electric power at voltage up to 33kv  beyond 33kv operating voltage pin type insulator become too bulky and uneconomical.

The cost of insulator beyond 33kv increase is given by

Cost ∝ V^x


Advantages of Pin Insulator

  • Pin type insulator has high mechanical strength.
  • It has a good creepage distance.
  • Pin type insulator used on the high voltage distribution line.
  • Construction is simple and requires less maintenance.
  • Pin type insulator can be used vertically as well as horizontally.

Disadvantages of Pin Insulator

  • Pin type insulator used up to 33kv operating voltage
  • Beyond 33kv cost increase and become uneconomical.
  • Replacement of insulator is expensive
  • Pin type insulator only used in the distribution line.

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