Dielectric Guard for Bird-Induced Flashovers on Transmission Towers
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Solution Overview
Problem
High voltage electrical transmission structures face flashovers due to birds bridging the gap between wires and grounded structures, leading to short circuits, which existing deterrents like needles and plastic shields are inadequate in preventing, especially as they can be hazardous and require de-energizing the system for installation.
Innovation Solution
A plastic guard is affixed over the lower portion of angled struts on grounded structures, featuring an angled shape and extending bottom portion to prevent birds from landing, providing an insulating surface distance that prevents flashovers, and can be securely attached without de-energizing the circuit, using bolts and snap pins for installation safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If needles or spikes are affixed to struts to deter birds, then bird deterrent effectiveness is improved, but bird safety deteriorates due to injury risk
Solution Approach 1:
The patent introduces an insulating guard as an intermediary component between the bird and the grounded structure. The guard is made of insulating material and positioned to prevent direct contact between the bird and the ground, thereby eliminating the harmful effect of injury while maintaining the flashover prevention function.
Solution Approach 2:
The patent converts the potentially harmful grounded structure into a beneficial insulating barrier. By covering the grounded strut with insulating material, the structure that could cause harm (grounded metal) is transformed into a protective element that prevents both injury and flashover.
2Reliability
If plastic shields are attached to wires to prevent flashover, then flashover prevention is improved, but wire positioning stability deteriorates under high winds
Solution Approach 1:
The patent extracts the flashover prevention function from the wire-mounted shields and relocates it to the ground-mounted insulating guard. This removes the large surface area shields from the wires, eliminating the wind-induced positioning instability while preserving the flashover prevention capability.
Solution Approach 2:
The insulating guard serves as a mediator that prevents flashover without being attached to the wire. By positioning the guard on the grounded structure rather than on the wire, the system avoids the stability issues associated with large shields on wires while maintaining effective flashover prevention.
3Length of stationary object
If plastic shields with large surface area are used to prevent flashover, then flashover distance is extended, but wind load on wires increases pushing wires closer to the tower
Solution Approach 1:
The patent extracts the flashover distance extension function from the large surface area shields and implements it through the insulating guard positioned on the grounded structure. This eliminates the wind load problem while maintaining the extended flashover distance through the insulating material's dielectric properties.
Solution Approach 2:
The patent changes the location and orientation of the insulating material from wire-mounted horizontal shields to ground-mounted vertical guards. This parameter change maintains the effective flashover distance through the insulating material while eliminating the large surface area exposed to wind, thus reducing wind load on the wires.
4Ease of manufacture
If conventional installation methods are used, then installation simplicity is maintained, but lineman safety deteriorates requiring de-energizing the system
Solution Approach 1:
The insulating guard acts as a mediator that enables safe installation without de-energizing the system. The guard's insulating properties create a safe working zone that protects linemen from electrical shock, allowing installation to proceed while the system remains energized.
Solution Approach 2:
The insulating guard is installed in advance to create a protective barrier before any maintenance work is performed. This preliminary action of establishing the insulating barrier enables subsequent safe work practices without requiring system shutdown.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively extends the flashover distance, preventing short circuits and ensuring lineman safety by insulating birds from the ground, reducing the need for large shields along wires and allowing installation without de-energizing the system, effectively addressing bird-induced flashovers on high voltage transmission structures.
Implementation Method 1
The guard is constructed of an insulating material having a thickness and other dielectric characteristics needed to prevent flashover between a large bird perched on the guard and the wire above the bird or a bird bridging the air gap between the guard and the wire
Data Source
AI summary
A conventional grounded steel tower, or other structure, supports multiple wires (e.g., 6) carrying multi-phase high voltage electricity (e.g., >100 kV). Each wire is supported by a ceramic insulator connected to a horizontal arm of the structure, where an angled strut helps support the arm. There are usually three tiers of wires. The closest distance between a wire and ground is typically between the wire and an angled strut below the wire, where the angled strut helps support a lower-tier wire. A guard formed of a dielectric is affixed to and covers the lower portion of the steel strut as well as any steel that outward extends beyond the strut. The guard prevents flashover between a wire and the underlying grounded strut if a large bird perches on the guard, since the bird will not be grounded by the strut.