Terminal Box Arc Detection and Earth Switching
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Solution Overview
Problem
In electric rotating machines, terminal boxes can be damaged by fault currents exceeding their capacity, posing safety risks due to the uncertainty of required fault current strength and mechanical limitations.
Innovation Solution
A method and arrangement that detects electric arcs within the terminal box and electrically connects phases to earth using high-speed switching elements, reducing the mechanical withstand requirements and mitigating high fault currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fault current strength of the terminal box is increased to handle higher fault currents, then the terminal box can withstand higher fault currents, but the size and mechanical complexity of the terminal box increases
Solution Approach 1:
The patent replaces the mechanical approach of increasing terminal box fault current strength with an electrical/electronic solution using arc detection means and high-speed switching elements. The detection means monitors for electric arcs indicating fault conditions, and the switching elements rapidly disconnect affected phases, eliminating the need for mechanically robust terminal box design to withstand high fault currents.
2Reliability
If overdimensioning of the terminal box is done to ensure sufficient fault current strength, then the terminal box can handle unexpected high fault currents, but the cost and mechanical limitations are worsened
Solution Approach 1:
The patent implements preliminary detection of fault conditions through arc detection means that continuously monitor the terminal box environment. By detecting arcs before they develop into severe fault conditions, the system can trigger protective switching actions in advance, preventing the need for overdimensioned terminal boxes designed to withstand worst-case scenarios.
3Productivity
If multiple machines are connected to the same bus, then the system capacity is increased, but the risk of high fault currents exceeding terminal box capacity increases
Solution Approach 1:
The patent implements a feedback mechanism where arc detection means continuously monitor fault conditions in real-time and provide immediate feedback to the control arrangement. When arcs indicating fault conditions are detected, the control arrangement rapidly actuates switching elements to disconnect affected phases, creating a closed-loop protection system that enables safe operation of multiple machines on the same bus.
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
Efficiently detects and eliminates fault situations, reducing damage to the terminal box and surrounding equipment, enhancing safety and allowing multiple machines to be connected without additional mechanical design changes, thus increasing fault current withstand capability.
Implementation Method 1
a detection means configured to detect an electric arc inside the terminal box
Data Source
Figure 1~2
Figure 3
Figure 4a~4e
AI summary
A method for fault protection of a terminal box of an electric rotating machine, and an arrangement comprising a terminal box (100) for an electric rotating machine (200) for electrically connecting the electric rotating machine to an electric system (300) for transmitting electric power between the electric system and the electric rotating machine in one or more phases (P1, P2, P3) via the terminal box, a detection means (11, 20, 21) configured to detect an electric arc inside the terminal box (100), and a switching means (S1, S2, S3, 12) configured to electrically connect each of the one or more phases to earth in response to the detection means detecting the electric arc inside the terminal box (100) or in response to the detection means detecting the electric arc inside the terminal box (100) and one or more predetermined conditions being satisfied.