DC Switch Arc Extinguishing via Sequential Contact Disconnection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DC circuit interrupters face challenges in extinguishing arcs effectively at high voltage and current levels, particularly in photovoltaic applications, where increased voltage and current exacerbate arc persistence, and the use of magnets to address this issue increases costs.
Innovation Solution
A switch apparatus with a rotatable shaft and multiple pairs of contacts, where one pair is disconnected before the other, utilizing permanent magnetic field elements to apply Lorentz forces and extinguish arcs only at the sacrificial contacts, optimizing arc extinction for both DC polarities while minimizing magnet usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnets are used to extinguish arcs in DC circuit interrupters, then arc extinction capability is improved, but device cost increases
Solution Approach 1:
The patent applies magnetic field elements only at specific locations where arcs are most problematic - namely at the contacts that remain after sequential disconnection. Rather than placing magnets at all contacts, the invention selectively positions magnetic field elements only at the 'other pair of contacts' that form arcs, creating local arc control where needed while avoiding unnecessary magnets elsewhere in the device.
Solution Approach 2:
The patent divides the contact system into two distinct pairs with different disconnection sequences. The first pair of contacts disconnects before the other pair, creating separate arc zones. Magnetic field elements are applied only to the second pair of contacts, segmenting the arc extinction function to where it is most needed rather than applying it uniformly across all contacts.
2Reliability
If multiple magnets are used to extinguish arcs at all contacts, then arc extinction is improved, but device complexity increases
Solution Approach 1:
The patent applies magnetic field elements only at specific locations where arcs are most problematic - namely at the contacts that remain after sequential disconnection. Rather than placing magnets at all contacts, the invention selectively positions magnetic field elements only at the 'other pair of contacts' that form arcs, creating local arc control where needed while avoiding unnecessary magnets elsewhere in the device.
Solution Approach 2:
The patent divides the contact system into two distinct pairs with different disconnection sequences. The first pair of contacts disconnects before the other pair, creating separate arc zones. Magnetic field elements are applied only to the second pair of contacts, segmenting the arc extinction function to where it is most needed rather than applying it uniformly across all contacts.
3Power
If DC voltage and current are increased in photovoltaic applications, then power handling capability is improved, but arc persistence worsens
Solution Approach 1:
The patent employs sequential disconnection where the first pair of contacts opens before the other pair. This preliminary action transfers the arc formation to a controlled sequence where arcs occur only at the second pair of contacts, which are positioned to work with the magnetic field elements. The preliminary disconnection of the first pair reduces the overall arc energy before the second pair disconnects.
Solution Approach 2:
The patent changes the temporal parameter of contact disconnection by implementing sequential rather than simultaneous opening. This parameter change in the disconnection timing allows arcs to be concentrated at specific contacts where magnetic field elements can be most effective, rather than arcs forming simultaneously at all contacts at high voltage and current levels.
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 high interruption capability for DC circuits of either polarity at a low cost, ensuring rapid arc extinction and reduced magnetic field element placement, thus enhancing performance and cost-effectiveness.
Implementation Method 1
Magnetic field elements in the form of permanent magnets are situated in the vicinity of the air gaps of only the other pair of contacts and apply Lorentz forces to the arcs to extinguish them
Data Source
AI summary
A switch apparatus usable in a DC circuit employs a rotatable shaft having conductors that are removably connected with two or more pairs of contacts that are situated on line conductors and load conductors and that are connected in parallel by the conductors on the shaft. In rotating the shaft to open the switch, one pair of the contacts is electrically disconnected prior to electrical disconnection of the other pair of contacts. Further rotation of the shaft causes the other pair of contact to eventually become disconnected. Electrical arcs thus form only at the air gaps between the other pair of contacts and the conductor. Magnetic field elements in the form of permanent magnets are situated in the vicinity of the air gaps of only the other pair of contacts and apply Lorentz forces to the arcs to extinguish them.