DC Switch Linkage Mechanism for Reliable Contact Separation
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Solution Overview
Problem
String inverters in photovoltaic systems face reliability issues due to aging contacts and increased friction between movable and stationary contacts, leading to unreliable switch-off during faults like overcurrent or short circuits, which affects the service life and safety of the inverter.
Innovation Solution
A direct current switch with an operating mechanism featuring a connecting rod assembly and a disconnector, including a handle, input and output shafts, and a releaser, which provides a larger driving force to separate the contacts even when friction increases, and includes a trip-free function to ensure reliable separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the inverter operates for a prolonged service life, then the inverter can provide continuous power conversion, but the contact surface between movable contact and stationary contact inevitably ages, leading to increased friction and rust
Solution Approach 1:
The input connecting rod is designed to collide with the output connecting rod before the normal switching operation, preliminarily building up sufficient driving force to overcome the friction and adhesion that develops during prolonged service. This preliminary action ensures that even aged contacts can be reliably separated when needed.
Solution Approach 2:
The operating mechanism transforms the simple rotational motion of the handle into a complex dynamic motion sequence through the connecting rod assembly. The input connecting rod's collision with the output connecting rod creates a dynamic impact force that exceeds the static friction force of aged contacts, enabling reliable switching throughout the inverter's service life.
2Ease of operation
If the movable contact and stationary contact are separated by conventional operating mechanisms, then the disconnector can switch off, but when friction or rust occurs between contacts, the driving force is insufficient to ensure reliable separation
Solution Approach 1:
The input connecting rod collides with the output connecting rod to preliminarily accumulate sufficient driving force before the actual contact separation occurs. This preliminary action ensures that the driving force exceeds the friction and adhesion forces even when contacts are aged.
Solution Approach 2:
The collision between the input connecting rod and output connecting rod generates a mechanical impact that creates transient high force, effectively overcoming the static friction and adhesion forces between aged contacts. This impact mechanism ensures reliable contact separation throughout the inverter's service life.
3Device complexity
If a simple operating mechanism is used, then the device complexity is low, but it cannot provide sufficient driving force when contacts experience rust or adhesion
Solution Approach 1:
The input connecting rod is designed to collide with the output connecting rod to preliminarily build up sufficient driving force. This simple collision mechanism adds minimal structural complexity while ensuring reliable contact separation even when contacts are aged or contaminated.
Solution Approach 2:
The input connecting rod acts as an intermediary that transfers and amplifies the driving force from the handle to the output connecting rod. This intermediary component enables reliable contact separation without significantly increasing the overall device complexity.
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 prolongs the service life and reduces maintenance costs by ensuring reliable separation of contacts, even under conditions of rust or adhesion, thereby improving the safety and reliability of the power converter.
Implementation Method 1
the input connecting rod collides with the output connecting rod, and the output connecting rod drives the output shaft to rotate
Data Source
AI summary
An operating mechanism includes an input shaft, an output shaft, and a connecting rod assembly, and the connecting rod assembly includes an input connecting rod and an output connecting rod. A disconnector includes a plurality of stacked sub-switches, and each sub-switch includes a movable contact and a stationary contact. The input shaft is fastened to the handle, the connecting rod assembly is configured to be in transmission connection to the input shaft and the output shaft, and the output shaft is configured to drive the movable contact to rotate. The handle is configured to drive the input shaft to rotate, and the input shaft is configured to drive the input connecting rod to rotate, so that the input connecting rod collides with the output connecting rod, and the output connecting rod drives the output shaft to rotate, to separate the movable contact from the stationary contact.