Transductor Circuit for DC to AC Conversion in Switching Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current DC circuit breakers face challenges in accuracy and cost, particularly in photovoltaic applications where low short circuit current levels make thermal and magnetic trip units unreliable and expensive DC electronic trip units necessary.
Innovation Solution
An electrical switching apparatus with a transductor circuit and an AC electronic trip circuit that converts DC current to AC, allowing for precise control of separable contacts using AC electronic trip units, which are economical and accurate, and can be used for both AC and DC applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DC electronic trip unit is used in DC circuit breakers, then tripping accuracy is improved, but cost increases significantly
Solution Approach 1:
The patent introduces a transductor circuit as an intermediary device that converts DC current into AC current. This AC current can then be processed by conventional AC electronic trip units, which are more cost-effective than DC electronic trip units. The transductor acts as a mediator that bridges the gap between DC circuit protection needs and AC trip unit capabilities, achieving both accuracy and cost-effectiveness.
Solution Approach 2:
The patent changes the electrical parameter of the current from DC to AC by using a transductor circuit. This parameter transformation allows the use of AC electronic trip units (which are more economical and readily available) to protect DC circuits. The transductor converts the DC current into an AC signal that the trip unit can process, thereby reducing cost while maintaining tripping accuracy.
2Ease of manufacture
If thermal and magnetic trip units are used in photovoltaic applications with low short circuit current, then cost is reduced, but tripping accuracy and reliability deteriorate
Solution Approach 1:
The transductor circuit serves as an intermediary that enables AC electronic trip units to accurately detect low current levels in photovoltaic applications. By converting DC current to AC, the system can utilize the superior measurement capabilities of AC electronic trip units even at low current levels typical of photovoltaic systems, achieving both cost-effectiveness and high tripping accuracy.
Solution Approach 2:
The patent replaces mechanical thermal and magnetic trip units with an electronic trip unit system. The transductor circuit combined with AC electronic trip unit substitutes the mechanical sensing and tripping mechanism with an electronic one, providing superior accuracy and reliability while maintaining cost-effectiveness in photovoltaic applications.
3Ease of manufacture
If AC electronic trip units are used directly in DC applications, then cost is reduced, but operation becomes inoperable without time varying magnetic field
Solution Approach 1:
The transductor circuit acts as a necessary intermediary that enables AC electronic trip units to operate in DC applications. By converting DC current into AC current, the transductor provides the time-varying magnetic field that AC electronic trip units require to function, thereby making them operable in DC environments while maintaining their cost advantages.
Solution Approach 2:
The patent changes the current type parameter from DC to AC using the transductor circuit. This parameter transformation enables AC electronic trip units to operate in DC applications by providing them with AC current, thus resolving the operability issue while maintaining cost-effectiveness.
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 enhanced tripping accuracy and cost-effectiveness by using AC electronic trip units, overcoming the limitations of thermal and magnetic trip units in DC applications, especially in photovoltaic systems with low short circuit currents.
Implementation Method 1
a transductor circuit that applies a bias alternating voltage between at least one set of the secondary terminals of the alternating current transformers and outputs an alternating current proportional to the direct current
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An electrical switching apparatus (1) includes a transductor circuit (100) that senses a direct current between at least one input terminal and at least one output terminal and outputs an alternating current proportional to the direct current between the input terminal and the output terminal. The electrical switching apparatus (1) also includes an alternating current electronic trip circuit (200) configured to control pairs of separable contacts (406) to separate based on the alternating current output from the transductor circuit (100).