Servo Switch Drive with Redundant Position Feedback Safety Control
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Solution Overview
Problem
Existing switch arrangements, particularly on-load tap changers and other safety-critical components in electrical substations, face challenges in ensuring operational safety and reliability due to potential feedback system failures, which can lead to incorrect position determination and operational disruptions.
Innovation Solution
The implementation of a redundant feedback system that determines the position of the drive shaft using multiple methods, including absolute and incremental position values, and a programmable safety controller with dual processor units to ensure plausibility checks and initiate safety measures, such as controlled shutdowns, to maintain safe operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback system is used to determine the position of the drive shaft, then the switch can be controlled to a desired position, but the system may fail due to incorrect position determination
Solution Approach 1:
The patent implements a feedback system with dual position determination methods (absolute encoder and incremental encoder) that continuously monitor the drive shaft position. The control device compares both feedback signals to verify position accuracy, and can initiate safety measures if discrepancies are detected, thereby resolving the contradiction between reliability and measurement precision
Solution Approach 2:
The system performs preliminary verification of position determination by comparing absolute and incremental position values before executing switching operations. This preliminary check prevents incorrect operations and ensures reliable position data is used for control decisions
2Reliability
If a redundant feedback system with dual processor units is implemented, then operational reliability is enhanced, but device complexity increases
Solution Approach 1:
The control device is segmented into two independent processor units (first and second processor units) that each independently determine position values using different feedback methods. This segmentation allows parallel verification of position data, enhancing reliability while maintaining manageable complexity through modular architecture
Solution Approach 2:
The system changes the parameter of position determination by using two different measurement methods (absolute position encoding and incremental position encoding) simultaneously. This parameter diversity provides cross-verification capability that improves reliability without requiring complex redundant hardware systems
Data Source
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AI summary
The invention relates to a switch assembly (1) comprising a switch (17) and a servo drive system. The servo drive system has a driveshaft (17), a motor (12) for driving the driveshaft (16), a power section (11) for supplying energy to the motor (12), a control unit (10), and a feedback system (4). The feedback system (4) is designed to determine at least two values for the absolute position of the driveshaft (16) and generate a feedback signal on the basis of the at least two values. The control unit (10) is designed as a programmable safety controller and is designed to actuate the power section (11) on the basis of at least one target value. On the basis of the feedback signal, the control unit (10) is designed to influence the operation of the motor (12), identify the presence of at least one safety-relevant event, and transmit at least one control signal to the power section (11) in the case of the safety-relevant event. The power section (11) is designed to initiate or carry out at least one safety measure on the basis of the control signal.