Sensor Isolation Circuit for Gas Turbine Ground Loop Prevention
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Solution Overview
Problem
Gas turbine engine systems face challenges in providing accurate sensor signals independent of ground connections, which can lead to ground loops and degrade circuit performance, particularly due to the use of bulky transformers that offer limited frequency response.
Innovation Solution
A sensor isolation circuit comprising a voltage divider circuit, a clamping circuit, and a gain circuit is used to convert differential sensor signals into single-ended output signals independent of ground, eliminating the need for duplicate ground connections and separate power sources, and providing improved frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transformers are used to electrically isolate the sensor from the circuits, then ground loop interference is prevented, but the device becomes bulky and frequency response is limited
Solution Approach 1:
The patent replaces the mechanical/physical transformer-based isolation system with an electronic circuit solution. The isolation circuit uses operational amplifiers, resistors, and capacitors to achieve electrical isolation without the bulky magnetic components of transformers, thereby reducing size and weight while maintaining isolation functionality.
Solution Approach 2:
The patent changes the operating parameters of the isolation circuit by using active electronic components (operational amplifiers) that can operate across a wider frequency range compared to transformers. This allows the system to achieve both isolation and improved frequency response by adjusting circuit parameters such as gain, bandwidth, and component values.
2Reliability
If transformers are used for sensor isolation, then ground loop interference is prevented, but the frequency response is limited
Solution Approach 1:
The patent replaces the transformer-based isolation system with an electronic circuit using operational amplifiers and passive components. This substitution enables the system to achieve both ground loop prevention and superior frequency response characteristics, as electronic circuits can respond more quickly across a broader frequency spectrum compared to magnetic transformer components.
Solution Approach 2:
The patent optimizes the frequency response by adjusting circuit parameters including operational amplifier selection, resistor and capacitor values, and feedback network configuration. These parameter changes enable the isolation circuit to operate effectively across a wider frequency range while maintaining signal integrity and isolation performance.
3Reliability
If independent power supplies are used for each circuit connected to a sensor, then circuit isolation is achieved, but device complexity and cost increase
Solution Approach 1:
The patent merges the power supply requirement into a single shared power source for the isolation circuit, eliminating the need for multiple independent power supplies. The operational amplifier-based isolation circuit can operate from a single power supply while maintaining isolation functionality, thereby reducing system complexity and component count.
Solution Approach 2:
The isolation circuit is designed to perform multiple functions using a single power supply: it provides signal isolation, amplification, and level shifting all while operating from one common power source. This multi-functional approach eliminates the need for separate power supplies for each function, reducing overall system complexity.
4Reliability
If transformers are used for sensor isolation, then ground loop interference is prevented, but the overall system cost increases
Solution Approach 1:
The patent replaces expensive transformer components with cheaper electronic circuit elements such as operational amplifiers, resistors, and capacitors. These standard electronic components are generally less costly than audio or isolation transformers, reducing the overall bill of materials cost while maintaining the required isolation functionality.
Solution Approach 2:
The patent substitutes the mechanical transformer-based isolation approach with an electronic circuit implementation that uses readily available, cost-effective components. This substitution reduces both component cost and assembly complexity, making the isolation system more economical to manufacture while achieving the same ground loop prevention objective.
Data Source
AI summary
Isolation circuits, turbine data acquisition systems, and related methods are disclosed. One example isolation circuit includes a voltage divider circuit for coupling to an operational sensor, a clamping circuit connected to said voltage divider circuit and a gain circuit connected to said clamping circuit. The voltage divider circuit is configured to divide an amplitude of a signal received from the sensor. The clamping circuit is configured to limit voltage from said voltage divider circuit. The gain circuit includes an output. The isolation circuit provides a single-ended output signal to the output of the gain circuit as a function of the sensor signal and independent of ground.