The Pin Insulator
For voltages up to 33 kV, the pin insulator is utilized in power distribution. It is positioned on the supporting tower’s cross arm. The conductor can be kept in the grooves on the top of the pin insulator. An annealing binding wire made of the same substance as the conductor ties the conductor towards the insulator inside the top groove for straight-line installations and the side groove for angled positions. The insulator body has a lead thimble that is cemented into it to hold the pin.
Non conducting material
Non-conducting materials, such as porcelain, ceramics, silicon rubber, polymeric, etc., are used in pin insulators. In comparison to porcelain insulator material, polymeric pin insulator material weighs more.
For high voltage, several pieces are bonded together to maintain the required thickness of the insulator, whereas low voltage uses a single-piece pin insulator. The leakage current has a good path thanks to the insulator.
The damp and unclean surface has a lower flashover voltage than clean and dry surfaces. The combination of all direct air lengths results in the dry arcing distance. The symbol for it is (a+b+c). (A+B+C) is the total damp arcing length.
Benefits of a Pin Insulator
- It has a strong mechanical structure.
- The creepage distance of the printed circuit board insulator is good.
- The high voltage distributing line uses it.
- The pin-type insulator’s construction is straightforward and requires little upkeep.
- It could be used both horizontally and vertically.
- The spindle should indeed be utilized with it.
- Just the distributing line uses it.
- The voltage rating has a cap, which is 36kV maximum.
- The insulator’s pin harmed the threads of the insulator.
Applications include the use of this insulation in the transmission of electricity up to 33 kV.
• On a straight run, these insulators are utilized on intermediate poles.
• A pin-type insulator is utilized in place of two suspension-type insulators.
Insulator Failure Causes
Insulator electrical failure can be caused by flashover or piercing. In the event of a rupture, the arc travels through the insulator’s body. The arc discharges between both the conductor as well as the ground through the air around the insulator are what causes the flashover.
The line surge or the development of a moist conducting layer and over-insulator surface are the main causes of the flashover. The overheating does not harm the insulator, but the hole has rendered it unusable.
The insulator has a thick enough layer of material to prevent punctures during surge conditions. By raising the impedance to leakage currents, the flashover is minimized. Petticoats, also known as rain shelters, are constructed in layers to extend the length of the leakage channel. The rain sheds provided enough leakage resistance to stop a flashover by keeping the interior surface fairly dry in wet weather.
Pin insulators have a limited range of applications over 66kV due to their increasing size, weight, and expense. As a result, high voltage work uses suspending insulators.
Considerations for Design
The insulator’s base can also be linked to sustaining the earth’s potential structure, and the conductor is attached to the insulator.
The insulator must withstand any potential stresses between the conductor and the earth. Flashover separation is the separation between the earth and the conductor, the insulators surrounding them, and the electrical discharges through the air.
The insulator’s exterior surface will practically become conducting once it has become wet. As a result, in an insulator, the flashover area will be shorter.
To shield the interior components from the rain, the upper insulator is designed to resemble an umbrella. Rain retains the largest flashover voltage on the top dress’s upper face. It is possible to create rain sheds over insulators to shield the power distribution from disruptions.
Design considerations for pin insulators
The following factors must be taken into account while designing a pin insulator. The wire is fastened to the insulator’s top, and the insulator’s base can then be connected to maintain the earth’s optimal utilization. The insulator must also be able to withstand any probable friction between both the conductors and the ground.
It is also referred to as the separation between earth and the conductor, insulator, and air used to conduct electrical current. The external surface of the insulator is almost conducting when it is moist. The gap in insulators is finally shortened.
Why the pin insulator fails?
The electric loss of both insulators leads to puncture or flashover. As the body of the insulator is pierced, the arc moves through it. The arc discharges from the air overlaying the insulator between the conductor and the ground, causing the flashover. Line surging or developing a moist conduction layer here on the insulator’s surface are the main contributors to the flashover. The flashover does not damage the insulator, but the perforation renders it worthless.
The insulator gives the material enough thickness to prevent a surging perforation. By strengthening the leakage resistance, the flashover is reduced to a minimum. The duration of the leaking path is extended by adding more layers, or “petticoat.” The dress provided enough leakage resilience to prevent a flashover by keeping the inside surface fairly dry in wet conditions. The pin insulator’s use of over 66kV is constrained by the device’s rise in size, weight, and price. Suspended insulators are thus employed for high voltage operations.