Electromechanical Contactor Control Against High-Current Levitation
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Solution Overview
Problem
Existing electromechanical switching devices are not suitable for high voltage electrical power circuits, as they can experience 'levitation' phenomena leading to unwanted opening of the main contactor and electric arcs, particularly at voltages above 300 V, where short-circuit currents can initiate premature opening and cause degradation.
Innovation Solution
A switching device with a main contactor, spring, control power supply, and actuator that includes a current sensor to detect high currents and temporarily increase the actuator's force, using a resettable protection system to maintain a higher control signal level until the current exceeds a threshold, thereby preventing untimely state changes and controlling the duration of the signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator is designed to generate sufficient switching force to close the main contactor, then the contactor can be reliably closed, but the contactor may experience unwanted opening due to 'levitation' phenomena during high short-circuit currents
Solution Approach 1:
The control signal level is dynamically adjusted based on detected current conditions. During normal operation, a first control signal level is applied to maintain the contactor in the closed state. When high current is detected, a second control signal level higher than the first is applied to generate additional electromagnetic force that overcomes the levitation phenomenon and prevents unwanted opening.
Solution Approach 2:
A current detection device provides feedback about the current flowing through the contactor to the control device. Based on this feedback, the control device automatically adjusts the control signal level applied to the actuator, increasing it when high current is detected and decreasing it when normal current conditions prevail, thereby preventing levitation phenomena.
2Reliability
If a higher control signal level is continuously applied to prevent levitation, then the contactor remains reliably closed during high currents, but energy consumption increases and the contactor may not open when needed
Solution Approach 1:
The control signal level is dynamically adjusted based on detected current conditions. During normal operation, a first control signal level is applied to maintain the contactor in the closed state. When high current is detected, a second control signal level higher than the first is applied to generate additional electromagnetic force that overcomes the levitation phenomenon and prevents unwanted opening.
Solution Approach 2:
A current detection device provides feedback about the current flowing through the contactor to the control device. Based on this feedback, the control device automatically adjusts the control signal level applied to the actuator, increasing it when high current is detected and decreasing it when normal current conditions prevail, thereby preventing levitation phenomena.
3Use of energy by moving object
If the control signal level is reduced to save energy during normal operation, then energy consumption decreases, but the contactor becomes vulnerable to unwanted opening during high short-circuit currents
Solution Approach 1:
The control signal level is dynamically adjusted based on detected current conditions. During normal operation, a first control signal level is applied to maintain the contactor in the closed state. When high current is detected, a second control signal level higher than the first is applied to generate additional electromagnetic force that overcomes the levitation phenomenon and prevents unwanted opening.
Solution Approach 2:
A current detection device provides feedback about the current flowing through the contactor to the control device. Based on this feedback, the control device automatically adjusts the control signal level applied to the actuator, increasing it when high current is detected and decreasing it when normal current conditions prevail, thereby preventing levitation phenomena.
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 solution effectively prevents premature opening of the main contactor during high short-circuit currents, ensuring reliable operation at high voltages by dynamically adjusting the actuator's force and signal duration, thus avoiding 'levitation' phenomena and maintaining the contactor in the correct state.
Implementation Method 1
a coil 18 configured to cause the main contactor 12 to close and to hold it in the closed state when the coil 18 is energized
Implementation Method 2
a spring 20 configured to cause the main contactor 12 to open and to hold it in the open state when the coil 18 is no longer energized
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a switching device (30) comprising at least one main contactor (34), an actuator (40) configured to cause a change of state of the main contactor (34) from a first state to a second state, against a force generated by a spring (42), the actuator (40) being powered by a control signal (Sc) equal to a first level (S1) to cause the change of state of the main contactor (34) and then to a second level (S2), lower than the first level (S1), to maintain the main contactor (34) in the second state. The switching device (30) includes at least one current sensor (48) configured to drive the control signal (Sc) so as to increase it to a third level (S3) higher than the second level (S2) if the current flowing through the main contactor (34) is greater than or equal to a given operating threshold in order to prevent an unintended change of state of the main contactor.The switching device (30) includes a resettable protection system to control the duration of the control signal (Sc) held at the third level.