Tandem Fuse Holder Structure to Block False Single-Fuse Insertion
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Solution Overview
Problem
Existing protective appliances allow the insertion of inappropriate single fuses instead of tandem fuses, leading to potential arc formation and circuit interruption due to insufficient contact pressure, which can result in fire or unnecessary circuit disruption.
Innovation Solution
A protective appliance design with a cover featuring two chambers and a resilient selecting mechanism that ensures only tandem fuses can be properly inserted, preventing single fuses from establishing electrical contact by deflecting their caps away from conductive seats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective appliance is designed to receive a tandem fuse, then the nominal capacity and safety are improved, but the device complexity increases due to the need for prevention mechanisms against false fuse insertion
Solution Approach 1:
The seat on the cover is divided into two chambers, each capable of receiving a single fuse. This segmentation allows the seat to accommodate either one tandem fuse (occupying both chambers) or prevent insertion of inappropriate single fuses, thereby maintaining safety without requiring complex prevention mechanisms
Solution Approach 2:
A resilient selecting means acts as an intermediary element between the two chambers. This selecting means detects whether a tandem fuse is properly inserted and enables or disables the electrical connection accordingly, providing a simple yet effective safety mechanism that does not significantly increase device complexity
2Ease of operation
If a single fuse is inserted instead of a tandem fuse, then the ease of operation is improved, but the contact pressure becomes insufficient leading to arc formation and potential fire
Solution Approach 1:
The resilient selecting means is pre-positioned to detect the presence of a tandem fuse before electrical connection is established. By performing this check in advance, the system prevents insufficient contact pressure and potential arc formation before they can occur, maintaining safety while allowing easy operation when the correct fuse type is used
Solution Approach 2:
The electrical connection capability is extracted or disabled when an inappropriate single fuse is detected. The resilient selecting means effectively removes the harmful connection path when a single fuse is inserted, preventing arc formation while allowing straightforward insertion of the correct tandem fuse
3Ease of operation
If a single fuse is inserted instead of a tandem fuse, then the ease of operation is improved, but the nominal capacity becomes insufficient leading to unnecessary circuit interruption
Solution Approach 1:
The resilient selecting means performs a preliminary check to verify that a tandem fuse is properly inserted before enabling the electrical circuit. This preliminary action ensures that the circuit will operate reliably with appropriate nominal capacity, while still allowing easy insertion of the correct fuse type by users
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
Prevents the insertion of single fuses, ensuring reliable operation by maintaining sufficient contact pressure for tandem fuses, thereby avoiding arc formation and circuit disruption.
Implementation Method 1
a resilient selecting means (190) is mounted within the casing (1) and is arranged on the side (19) oppositely to the pivot point (21)
Implementation Method 2
the current is flowing through a part of melting material, so that the electric circuit, when exposed to overcurrent, is interrupted due to displacement of melted material
Implementation Method 3
which would lead to essential exceeding of a nominal capacity of the fuse with the possibility of burning of arc due to insufficient contact pressure during insertion thereof
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
The invention refers to a protective appliance (100) on the basis of a fuse (3, 3') with a melting member, which is suitable for receiving of a double i.e. tandem fuse (3') with melting members. The purpose of the invention is to prevent insertion of an inappropriate single fuse (3') into a protective appliance (100), which would lead to essential exceeding of a nominal capacity of the fuse (3, 3') with the possibility of burning of arc due to insufficient contact pressure between the fuse caps (32', 32'') and the belonging electrically conductive resting seats (17, 18) within the appliance casing (1). To this aim, a seat (23) is foreseen within the cover (2), which is adapted for receiving of a fuse (3, 3') and comprises two chambers (23', 23''), which are each per se adapted for receiving of a single fuse (3'). Said resting seats (17, 18) are arranged adjacent to the rear wall (12) of the casing (1), so that solely the fuse (3, 3'), which is inserted within the adjacent chamber (23'') can be brought into electric contact with them, but not also the fuse (3, 3'), which is inserted within the other chamber (21').