Multi-terminal Surge Arrester with External Mid-point Connection
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Solution Overview
Problem
Existing surge arresters integrated with metal oxide varistor devices in oil-filled tanks face challenges in testing for safe dielectric function and reliability due to limited test voltages, and they are not easily adaptable for external connections or mounting.
Innovation Solution
A multi-terminal surge arrester designed for medium to high voltages, operating in air insulation with externally accessible connections, featuring a cylindrical active part with metal-oxide varistor elements, an insulating housing, and a further electrode for mid-point electrical connection, which simplifies mounting and reduces production, mounting, and maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surge arresters are integrated with metal oxide varistor devices in oil-filled tanks, then insulation is provided, but testing for safe dielectric function and reliability is limited due to restricted test voltages
Solution Approach 1:
The invention extracts the surge arrester from the oil-filled tank environment and provides air insulation instead. The surge arrester is mounted on an insulating support structure that provides adequate insulation in air, allowing for unrestricted test voltages and comprehensive reliability testing without the constraints of oil-filled enclosures.
Solution Approach 2:
The invention changes the insulation medium from oil to air, and provides external electrical connections instead of internal integrated connections. This parameter change enables the surge arrester to be tested with higher voltages and allows for separate testing of the surge arrester component independent of the transformer, thereby improving both reliability verification and test voltage adaptability.
2Reliability
If surge arresters are integrated within transformer housing, then protection is provided, but adaptability for external connections and mounting is reduced
Solution Approach 1:
The invention segments the surge arrester from the transformer housing and provides it as a separate, independently mountable component. The surge arrester includes its own insulating support structure and external electrical connections, allowing it to be mounted separately on the transformer or other equipment, thereby improving mounting adaptability while maintaining protection reliability.
Solution Approach 2:
The surge arrester design with external connections and insulating support structure makes it universally applicable for mounting on various electrical equipment, not just integrated within specific transformer housings. The standardized external connections allow for flexible installation configurations and adaptability to different mounting locations and connection types.
3Reliability
If multiple electrical connections are provided within housing, then protection coverage is improved, but mounting complexity and cost increase
Solution Approach 1:
The invention introduces external electrical connections as intermediaries between the surge arrester and the equipment to be protected. Instead of providing multiple internal connections within the housing, the surge arrester connects to the equipment through external terminals and conductors, simplifying the internal structure while maintaining comprehensive protection coverage through proper external wiring.
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 provides a compact, cost-effective, and reliable surge arrester with enhanced protection against over-voltage transients, allowing for easy integration into existing systems and improved reliability through air insulation and external connections.
Implementation Method 1
varistor blocks providing a conduction path for diverting and/or bypassing over-voltage transients safely to ground in case a varistor-dependent threshold in voltage is exceeded
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A multi-terminal surge arrester (10) is proposed, which comprises an active part (12) extending along a longitudinal direction (14) of the surge arrester (10), a first electrode (20) resting against a first end (18) of the active part (12), and a second electrode (24) resting against a second end (22) of the active part (12), which second end (22) opposes the first end (18) in the longitudinal direction (14) of the surge arrester (10). The surge arrester (10) further comprises an insulating fixing device (26) mechanically connecting and fixing the first electrode (20) and the second electrode (24), and an insulating housing (38) arranged around the active part (12). The active part (12) comprises at least two metal-oxide based varistor elements (34) and a further electrode (40, 40a, 40b) arranged between the at least two varistor elements (34), which further electrode (40, 40a, 40b) provides an externally accessible electrical connection. Therein, the surge arrester (10) is adapted for being insulated by surrounding air.