Multi-Controller Contactor Override Relay for Cascading Failure Prevention
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Solution Overview
Problem
Redundant controller systems in contactor assemblies do not adequately address controller failures, leading to potential cascading failures due to erroneous contactor closure, which can cause parallel source inadvertent connection and overload.
Innovation Solution
A multi-controlled contactor system with an actuator control element and a relay that disrupts the return path of the actuator control signal when commanded to close erroneously, allowing either controller to independently force the contactor open based on override signals from override circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant controllers are used to control contactor closure, then reliability is improved through backup control capability, but controller failures can cause erroneous contactor closure leading to cascading failures
Solution Approach 1:
The patent applies preliminary anti-action by implementing override circuits that can preemptively counteract erroneous closure commands from failed controllers. The override circuits monitor controller status and can force the contactor open before a failure cascades through the system, effectively preventing the harmful effect before it propagates.
Solution Approach 2:
The patent introduces intermediary components including override circuits, relays, and diodes that mediate between the controllers and the contactor actuator. These intermediaries filter and validate control signals, preventing direct transmission of erroneous commands from failed controllers while allowing legitimate closure commands to pass through.
2Adaptability or versatility
If controllers can independently command contactor closure, then operational flexibility is improved, but parallel source inadvertent connection and overload can occur due to controller errors
Solution Approach 1:
The patent implements feedback mechanisms where override circuits continuously monitor the status of controllers and contactor position. This feedback allows the system to detect when a controller has failed or when the contactor is already closed, and automatically generate override signals to prevent erroneous dual-closure commands that could cause parallel source connection.
Solution Approach 2:
The patent uses intermediary components including diodes in the control circuitry that prevent simultaneous closure commands from multiple controllers. The diodes and relay logic act as intermediaries that validate commands before execution, ensuring only one controller can successfully close the contactor at a time and preventing parallel source connection hazards.
3Reliability
If a relay disrupts the actuator control signal return path, then contactor opening is forced even on controller failure, but device complexity increases
Solution Approach 1:
The patent applies inversion by controlling the return path of the actuator signal rather than the forward path. The relay is positioned to interrupt the return path to ground, and when activated by override circuits, it prevents the actuator from receiving the complete control signal, thereby forcing the contactor open. This inverted control approach provides reliable failure protection with relatively simple circuit implementation.
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
Prevents cascading failures by ensuring the contactor opens when it should, even if one controller fails to command it to do so, thereby preventing damage and overload.
Implementation Method 1
a relay coupled between the output of the actuator control element and ground that disrupts the signal from passing through the actuator control element when commanded by any of the one or more controllers
Data Source
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AI summary
A contactor system includes a contactor actuator (111) that causes an input bus bar to be electrically connected to an output bus bar and an actuator control element that controls operation of the contactor actuator. The actuator controller includes an input and an output. The system also includes a connection (470) that includes two inputs configured to receive signals from two or more controllers and provide one control signal to the input of the actuator control element and a relay (402) coupled between the output of the actuator control element and ground that disrupts the signal from passing through the actuator control element when commanded by any of the one or more controllers.