Plug-on Neutral Circuit Breaker Pivoting Terminal
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Solution Overview
Problem
Conventional plug-on neutral circuit breakers often deform due to excessive strain when installed in load centers with wire binding screws, requiring modifications to the load center for secure mating with neutral bars.
Innovation Solution
A plug-on neutral circuit breaker featuring a spring-loaded, pivoting neutral terminal that physically and electrically mates with a standard neutral bar without modifications to the load center, using a biasing member to ensure contact and reduce strain on the terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-sided jaw is used to engage both sides of the neutral bar, then the circuit breaker can be installed without modifications to the load center, but the jaw becomes overly strained and permanently deforms
Solution Approach 1:
The neutral terminal is divided into two separate legs instead of using a single two-sided jaw. Each leg independently engages one side of the neutral bar, distributing the mechanical strain across separate structural elements rather than concentrating it in a single component.
Solution Approach 2:
The neutral terminal is made pivotally coupled to the housing, allowing it to rotate dynamically during installation and operation. This dynamic capability enables the terminal to self-adjust and accommodate variations in neutral bar positioning without creating excessive strain on the engagement structure.
2Reliability
If wire binding screws are used to secure the neutral connection, then the connection is secure, but the installation process becomes more complex and time-consuming
Solution Approach 1:
The wire binding screws and neutral pigtail conductors are completely removed from the plug-on neutral circuit breaker design. The neutral connection is achieved through direct mechanical engagement of the neutral terminal legs with the neutral bar, eliminating the need for separate fastening components and simplifying the installation process.
Solution Approach 2:
The neutral terminal legs are designed to self-align and self-engage with the neutral bar through the pivotal coupling mechanism. During installation, the terminal automatically positions itself to make contact with the neutral bar, eliminating the need for manual alignment or additional fastening operations.
3Device complexity
If the neutral terminal is rigidly fixed to the housing, then the structure is simpler, but the terminal cannot accommodate variations in neutral bar positioning
Solution Approach 1:
The neutral terminal is pivotally coupled to the housing, providing a single degree of freedom that allows the terminal to rotate and accommodate variations in neutral bar positioning. This dynamic coupling adds minimal structural complexity while significantly improving adaptability to installation variations.
4Reliability
If the neutral terminal is spring-loaded, then contact pressure with the neutral bar is ensured, but the terminal may exert excessive force on the neutral bar
Solution Approach 1:
The biasing member provides a light spring load that ensures reliable electrical contact between the neutral terminal legs and the neutral bar. The spring force is calibrated to be sufficient for maintaining electrical connection without being excessive enough to cause damage to the neutral bar or surrounding components.
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
Enables seamless installation and secure electrical connection with existing load centers without deformation, allowing for the use of both plug-on neutral circuit breakers and conventional-style thermal magnetic circuit breakers on the same neutral bar.
Implementation Method 1
The biasing member biases the neutral terminal in a first rotational direction (e.g., counterclockwise) such that a portion of the other one of the legs is urged into contact with the standard neutral bar
Implementation Method 2
a neutral terminal that is pivotally coupled to a housing of the plug-on neutral circuit breaker
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A plug-on neutral circuit breaker includes a housing, a neutral terminal, and a biasing member. The neutral terminal is pivotally coupled to the housing and includes a body portion, a first leg, and a second leg. The first leg extends from the body portion in a first direction and the second leg extends from the body portion in a second direction. The biasing member is positioned within the housing and is configured to engage the second leg of the neutral terminal, thereby biasing the neutral terminal in a first rotational direction. The biasing of the neutral terminal in the first rotational direction causes a portion of the first leg of the neutral terminal to be urged into contact with a neutral bar of an electrical distribution apparatus in response to the plug-on neutral circuit breaker being installed in the electrical distribution apparatus.