DC Switching Device Arc Suppression via Segmented RC Snubber
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Solution Overview
Problem
Conventional RC snubber circuits face issues with contact welding and arc occurrence when switching direct current power, as the current discharge from the capacitor can be too large, and the resistance value needs to be contradictory for switching on and off states.
Innovation Solution
The proposed switching device incorporates a configuration with transfer switches and mechanical relays that manage the connection and disconnection of capacitors and resistors in parallel and series to control current flow and voltage, preventing contact welding and arc occurrence by ensuring appropriate resistance values and timing in switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an RC snubber circuit is used to suppress arc occurrence, then arc suppression is improved, but contact welding occurs due to large discharge current
Solution Approach 1:
The patent divides the single RC snubber circuit into two separate circuits: one with capacitor C1 for arc suppression during switch off, and another with capacitor C2 for controlled charging during switch on. This segmentation allows each circuit to be optimized for its specific function without causing harmful effects to the other.
Solution Approach 2:
The patent introduces a diode D1 as an intermediary element that controls the charging path of capacitor C2. The diode prevents direct discharge of C2 through the switch contact during turn-on, mediating the current flow to avoid contact welding while still allowing C2 to charge for subsequent arc suppression.
2Object-affected harmful factors
If resistance value is lowered to suppress arc, then arc suppression is improved, but discharge current becomes too large causing contact welding
Solution Approach 1:
The patent applies different resistance values to different parts of the switching circuit: resistor R1 with higher resistance for the C1 discharge path to limit current, and resistor R2 with lower resistance for the C2 discharge path optimized for arc suppression. This local quality differentiation allows each resistor to be optimized for its specific function.
Solution Approach 2:
The patent charges capacitor C2 in advance during the switch on-state through the diode D1 and resistor R2. This preliminary charging action ensures that C2 is ready to suppress arcs during the next switch off, while the diode prevents the charged C2 from causing harmful discharge current during the turn-on transition.
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 configuration effectively prevents contact welding during power switching on and arc occurrence during power switching off by managing current flow and voltage through controlled resistance and timing, ensuring reliable and safe switching operations.
Implementation Method 1
An RC snubber circuit in which a capacitor and a resistor connected in series extend between both ends of a switch
Implementation Method 2
An RC snubber circuit in which a capacitor and a resistor connected in series extend between both ends of a switch
Data Source
Figure 1~2
Figure 3~4B
Figure 4C~4D
AI summary
[Object] To provide a switching device in which it is possible to suppress an occurrence of an arc while preventing a contact welding of a switch. [Solution] Provided is the switching device including: a first circuit breaker mechanism provided in a path of current output from a direct current power supply; a second circuit breaker mechanism that is provided in parallel with the first circuit breaker mechanism in the path of current output from the direct current power supply, and is connected and disconnected with a time lag from the first circuit breaker mechanism; a capacitor provided between the direct current power supply and the second circuit breaker mechanism; and a discharging unit that is connected in parallel with the capacitor. A disconnection speed when the first circuit breaker mechanism is disconnected and a capacitance of the capacitor are set such that a dielectric strength voltage rises faster than a rising speed of a charging voltage of the capacitor, in a case where resistance of a load that receives a supply of the current from the direct current power supply is minimal.