Electric Automatic Switch Contact Segmentation for Arc Suppression
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Solution Overview
Problem
Existing automatic electric switches face challenges in ensuring proper successive interruption of contacts during over-current and short-circuit conditions, leading to irregular switching and electric arcs due to structural limitations, which affects their reliability and mass production feasibility.
Innovation Solution
A contact assembly with a movable contact element arranged flexibly over a pressure spring on a rotatable nonconductive element, equipped with an extinguishing chamber for the first contact and a slanted surface for successive opening of the second contact, preventing electric arcs by ensuring the second contact remains closed despite first contact opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movable contact element is arranged between fixed contact elements with springs, then the switch can provide circuit interruption upon over-current, but irregular interrupting of contacts occurs due to potent forces during operation especially in short-circuit current
Solution Approach 1:
The contact assembly is divided into two separate contact circuits: a first contact (main contact) and a second contact (auxiliary contact). This segmentation allows independent control and extinguishing strategies for each contact, enabling the first contact to be interrupted quickly while the second contact remains stable and closed during over-current conditions.
Solution Approach 2:
Different extinguishing qualities are applied to different contacts: the first contact is equipped with an extinguishing chamber with arc-quenching media to handle high-speed interruption, while the second contact is designed without an extinguishing chamber since it remains closed during over-current, eliminating the need for arc extinguishing capabilities at that location.
2Speed
If the first contact opens quickly upon over-current, then circuit protection is achieved, but electric arcs appear between contact elements causing damage
Solution Approach 1:
The high-speed opening of the first contact, which initially causes harmful electric arcs, is converted into a benefit by providing rapid circuit protection. The arc is contained within the extinguishing chamber where it is quickly quenched by the arc-quenching media, transforming the harmful arc into an effective protection mechanism that isolates the fault quickly.
Solution Approach 2:
An extinguishing chamber filled with arc-quenching media is introduced as an intermediary between the first contact elements. This mediator captures and extinguishes the electric arc that forms during rapid contact opening, preventing the arc from causing damage to the contact elements while maintaining the fast opening speed for circuit protection.
3Reliability
If the second contact opens simultaneously with the first contact, then the switch-off is complete, but electric arcs appear on the second contact and switch operation breaks down
Solution Approach 1:
The design ensures that the second contact remains closed as a preliminary action during over-current conditions, before any fault clearance is needed. This preliminary closed state of the second contact allows the first contact to open and be extinguished while the second contact provides a stable, arc-free path, preventing the harmful simultaneous opening scenario.
4Ease of manufacture
If conventional contact assembly structures are used, then manufacturing is simple, but the switch cannot withstand the forces during rapid commutation and provides insufficient switch-off repeats
Solution Approach 1:
The contact assembly is segmented into independent first and second contacts with separate support structures and extinguishing arrangements. This segmentation allows each contact to be optimized for its specific function while maintaining overall manufacturing simplicity through modular construction that can be produced using standard manufacturing processes.
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 design ensures reliable and efficient successive switching-off of both contact spots, preventing electric arcs and maintaining switch operation integrity, even under high current conditions, while allowing for cost-effective mass production.
Implementation Method 1
the move of a striker pin, which is axially moved by a quickly appearing electro-magnetic field within the coil, said field caused by high over-current within the coil
Implementation Method 2
a spring or springs cannot provide for the positioning of the movable contact element in this situation as foreseen or expected
Implementation Method 3
a bimetal linked in series in the secondary circuit in the switch switches off the switch of the secondary circuit
Implementation Method 4
an electric arc between the contact elements of the second contact, which is not adapted to extinguish the electric arc
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An electric automatic switch consists of a housing (1), wherein at one end of the housing (1) there is a connection terminal (2) for a supply connection of the protected circuit and at the opposite end there is a connection terminal (3) intended for discharge connection of the protected circuit, wherein a first switch (4) is intended within the housing (1) that is electrically connected with a coil (17) and a terminal (3), and a second switch (5), wherein a movable contact (6) is common for both said switches (4) and (5) and a contact (10) on the switch-off side of the switch (5) is connected in series to a resistance (12) and further to a means (13), preferably a bimetal, wherein the means (13) is connected to the first terminal of the coil (17) comprising a striker pin (18) that opens the switch (4) upon the appearance of over- current within the coil (17). In the area of the switches (4) and (5) there is a support (7) of the contact bridge (6), wherein said support (7) is rotatingly pivoted within a bearing (20) and simultaneously opened towards a spring (21) pushing the support (7) towards the switch (5) and on the support (7) there is a holder (22) of the movable contact bridge (6), further in its vicinity a support (25), onto which the upper extremity (26) of the bridge (6) leans with a force exerted by a spring (23), bearing (27) for the deflecting part of the means (13) and grip (28) of the knob (29) for manual switching on/off of the switch, in that the movable contact bridge (6) is formed in the shape of a cross, the upper member (30) of which is intended to properly position the bridge (6) in each operation mode of the switch and its cross members (30) are intended as complementary contacts to fixed contact elements (9) and (10) and the switch (5) and the lower longest member (15) of the movable contact element (6) is intended as a complementary contact to the fixed contact (16) of the switch (4).