Parallel Surge Arrester Sequencing for Continuous Overvoltage Protection
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Solution Overview
Problem
Existing surge protection systems for medium and high voltage electric power distribution lines face interruptions in protection when a single surge arrester fails, leaving equipment unprotected until maintenance can replace it, especially in areas with high lightning density.
Innovation Solution
A surge protection device comprising two surge arresters with different discharge voltage and voltage-current characteristics connected in parallel, where the first arrester disconnects from the circuit in a predetermined sequence as it becomes overloaded, ensuring continuous protection by transferring the load to the second arrester.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single surge arrester is installed to protect equipment, then the protection system is simple and cost-effective, but the protection is interrupted when the arrester fails
Solution Approach 1:
The protection system is segmented into multiple independent surge arresters (first and second arresters) with different discharge voltage characteristics. Each arrester operates independently and can be disconnected individually through ground lead disconnectors, allowing one to fail without compromising the other's ability to provide protection.
Solution Approach 2:
The patent employs surge arresters with different discharge voltage parameters - the first arrester has a lower discharge voltage and operates during normal surge conditions, while the second arrester has a higher discharge voltage and serves as backup. This parameter differentiation enables sequential operation and prevents simultaneous failure.
2Reliability
If two surge arresters are installed in parallel to provide continuous protection, then reliability improves, but the device complexity and cost increase
Solution Approach 1:
The ground lead disconnectors are pre-configured to automatically operate when their respective surge arresters become overloaded or fail. This preliminary action of automatic disconnection transfers the protective function to the remaining arrester without requiring manual intervention, maintaining continuous protection while simplifying the control system.
Solution Approach 2:
The ground lead disconnectors act as intermediary devices between the surge arresters and the ground connection. They mediate the failure process by isolating the failed arrester from the circuit while allowing the healthy arrester to continue providing protection, thus managing the complexity of the parallel system.
3Strength
If a surge arrester fails and is isolated by the ground lead disconnector, then the failed arrester is protected from further damage, but the protected equipment becomes unprotected
Solution Approach 1:
The system incorporates a backup surge arrester that is pre-positioned and ready to provide protection. When the first arrester fails and is disconnected, the second arrester immediately becomes the active protective element, cushioning the equipment against surge damage during the transition and eliminating unprotected periods.
Solution Approach 2:
The failed surge arrester is discarded from service through automatic disconnection by the ground lead disconnector, while the system recovers protective capability by transferring the load to the second arrester. This discarding and recovering mechanism ensures that failed components are isolated without compromising overall system protection.
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
This solution maintains uninterrupted protection for the electric system by allowing the second arrester to take over when the first becomes overloaded, reducing the risk of equipment damage and minimizing downtime in case of arrester failure.
Implementation Method 1
The varistors provide either a high or a low impedance current path between the electrodes depending on the voltage appearing across the varistors themselves. More specifically, at the power system's steady state or normal operating voltage, the varistors have a relatively high impedance. As the applied voltage is increased, gradually or abruptly, the varistors' impedance progressively decreases until the voltage appearing across the varistors reaches the elements' breakdown voltage, at which point their impedance dramatically decreases and the varistors become highly conductive.
Implementation Method 2
The ground lead disconnector attached to the ground end of the arrester operates and isolates the arrester from the circuit.
Data Source
AI summary
A surge protection device and method for protecting an electric system against overvoltage occurrences, the surge protection device includes a first surge arrester and a second or additional surge arresters connected electrically in parallel, the first surge arrester and the second surge arrester are configured to be disconnected from the electric system in a sequential predetermined order as each one is overloaded and becomes unusable as a surge arrester, remaining the electric system protected until the last one is disconnected. Various combination of externally gapped, internally gapped, and ungapped surge arresters are used to create the uninterruptable protection in the electric system.