An insulator’s primary function is to provide electrical isolation between current-conducting parts and non-conductive paths by delivering high resistance to electric current flow. A conductor insulator supports the conductors and prevents current flow between the conductor and the pole or the earth in overhead lines. This guide is all about pin-type insulator in detail.
Pin type Insulator
An insulator used to prevent physical reinforcement from contacting a wire, such as a utility pole pin, is called a pin insulator. Various power transmission systems use pin insulators for voltages as high as 33 kV. It is mounted on the cross arm of the tower that supports it. Several grooves are located on the top of the pin insulator to hold the conductor in place.
In the top and side grooves of the insulator, angled binding wires of the same material as the conductor connect the insulator. Pins are received in insulators by a lead thimble cemented into the body. Three-part pin insulators, one-part pin insulators, and two-part pin insulators may be used depending on the voltage application. In order to provide enough insulation, the thicker the insulator, the higher the voltage.
Properties of pin-type insulator
To choose pin-type insulators, you should ensure they have these basic properties:
- High resistance to electricity: To prevent voltage leakage, insulators must have strong electrical resistance.
- High mechanical strength: The pin insulator must be sturdy and robust enough to resist mechanical forces such as wind loads.
- Puncture strength: The puncture strength should be higher than the flashover strength.
- Non-porous: Pin insulator materials should not absorb impurities that may interfere with their performance.
What are the causes of pin-type insulator failure?
Proper design will allow the insulator to withstand electrical and mechanical stresses. As insulators are primarily subject to electrical stress based on line voltage, it is essential to pick the appropriate insulators based on the line voltage. A puncture or flashover can damage an insulator under excess electrical pressure.
• Factor of safety
It’s a measure of how much puncture potency there is about how much flash overvoltage there is. It is necessary to protect the pin-type insulator with a high safety factor value in order to ensure that a flashover occurs at least once before the insulator is punctured. It is estimated that this type of insulator has a safety factor value of approximately 10.
• The flashover
Flashover occurs when an arc forms between the pin of an insulator and the conductor of a line, resulting in an electrical discharge.
• The Puncture
When an electrical discharge punctures an insulator from the conductor to the pin, the conductor can be the conductor, or the pin can be the pin. It is essential to use an insulator material with enough thickness to evade punctures. In the event of such a puncture, the insulator will be permanently damaged.
Working of pin type insulator
During installation, the insulator’s top is connected to the conductor, while its base is connected to a ground or supporting structure. In addition to maintaining its stability, this connection is the key to the insulator’s performance.
As a result of the mechanical stress exerted between the earth and the conductor, the insulator is generally subject to mechanical stress. Due to its positioning between the two structures, the insulator plays a particularly important role in this situation.
An electric discharge is referred to as a flashover if it occurs between a conductor, the earth, the insulator, and the flashover distance.
Rain or humidity can cause the insulator to become wet, thus reducing the flashover distance. Due to this, the insulator becomes more electrically conductive, resulting in decreased efficiency.
As a result of the umbrella-shaped insulator, such a problem can be avoided because moisture is not absorbed into the base of the insulator.
In addition, the insulator’s upper petticoat is well-inclined to maintain a high flashover even during rainstorms. It will result in minimal voltage disturbances at the end of it.
Conductors will remain suspended from poles or other relevant structures without interference.
Pros of pin-type insulator
- A pin-type insulator is used for high voltage distribution lines.
- There is a simple construction process and less maintenance involved.
- There is a reasonable creep age distance with this product.
- Pin-type insulators are useful both horizontally and vertically.
- There is a high mechanical strength to pin-type insulators.
Cons of pin type insulator
- Replacement of the insulator is expensive
- More than 33kv, costs increase and become uneconomical.
- Insulators of the pin type are only used in distribution lines.
- Up to 33kv operating voltage can be handled with pin-type insulators.
FAQs (Frequently Asked Questions)
What is the purpose of insulators?
Electrical equipment contains insulators that separate and support conductors without allowing current to flow between them. Cable insulation, electrical equipment, and other insulating materials are sold bulk.
What are the uses of pin insulators?
Insulators, such as pin insulators, isolate wires from physical reinforcement, such as utility pole pins. A pin insulator is used in power delivery systems with up to 33 kV voltages. Located on a supporting tower’s cross arm, it supports the building. There are grooves at the top of the pin insulator to hold the conductor in place.
How does a cap and pin insulator work?
Ceramic or glass cap and pin insulators are typically used to suspend or tension overhead transmission lines above 33 kV, as well as to connect substation busbars at high levels. By arranging the required number of units in a string, virtually any creepage distance can be achieved.
How do pin sizes differ?
One inch is a standard professional size. It is considered significant when the length exceeds 1.5 inches. Trading pins are generally recommended to be 1.5 inches to 3 inches in diameter. In the case of a long horizontal corporate logo or design, a longer staple is required.
Why is the pin insulator shaped like an umbrella?
An insulator is designed to keep rain out of its lower section by having an umbrella-like design. Insulators have ridges around them that keep their inner sides dry, referred to as “rain sheds.” These devices increase the creepage distance between the energized wire and the mounting pin.
What is the reason for not using pin insulators above 33kv?
Operating voltages more significant than 33 kV are not economical for pin-type insulators. As part of the supporting tower, it is attached to the cross arm. A groove is provided at the top of the pin insulator to keep the conductor in place.
How does a pin-type insulator work?
Insulators isolate wires from physical supports, such as pins (dowels of wood or metal with screw threads) on telegraph poles and utility poles. A single layer shape from a non-conductive material, usually porcelain or glass, is called an inductor.