Inductive Sensor Circuit With Secondary-Side Intrinsic Safety Limits
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Solution Overview
Problem
Existing sensor designs connected via inductive interfaces in explosive areas require complex and costly certification processes due to the need for both sides of the circuit to 'know' each other's parameters, leading to large circuit board space requirements and questionable global acceptance.
Innovation Solution
A sensor with an ex-circuit that limits input voltage and current on the secondary side independently, allowing for certification of the sensor and cable separately, enabling any certified combination of sensor and cable to be used in explosive areas without needing to consider the primary side's parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both primary side and secondary side are designed to know each other's parameters, then intrinsic safety can be ensured, but device complexity and circuit board space increase significantly
Solution Approach 1:
The patent segments the intrinsic safety function into two independent parts: the primary side cable circuit is certified with maximum output parameters, and the secondary side sensor circuit is certified with maximum input parameters. This segmentation eliminates the need for both sides to know each other's detailed parameters, reducing circuit complexity while maintaining safety through independent certifications.
Solution Approach 2:
The patent extracts the safety-critical parameter knowledge from the interaction between primary and secondary sides. Instead of requiring mutual knowledge of all parameters, only the maximum output parameters of the primary side and maximum input parameters of the secondary side are extracted and used for independent certification, simplifying the overall system design.
2Reliability
If both primary side and secondary side are designed to know each other's parameters, then intrinsic safety can be ensured, but certification process becomes more difficult and costly
Solution Approach 1:
The patent segments the certification process into two independent certifications: one for the primary side cable circuit (with maximum output parameters) and one for the secondary side sensor circuit (with maximum input parameters). This segmentation allows each side to be certified independently without requiring detailed knowledge of the other side, making the certification process easier and more cost-effective while ensuring intrinsic safety.
3Reliability
If secondary-side input parameters are limited by primary side, then intrinsic safety is maintained, but sensor design flexibility is reduced
Solution Approach 1:
The patent segments the parameter specification into independent maximum output parameters for the primary side and maximum input parameters for the secondary side. This allows the sensor (secondary side) to be designed with optimized parameters for its specific application, while the cable (primary side) is designed independently with its own optimization parameters. The segmentation enables design flexibility on both sides while maintaining intrinsic safety through the inductive interface.
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 approach simplifies the certification process, reduces circuit complexity, and allows for optimized sensor design and functionality, enabling precise measurements while ensuring intrinsic safety in explosive environments.
Implementation Method 1
the secondary coil L2, which receives an electrical signal from a primary coil L1 associated with the secondary coil L2
Data Source
AI summary
Disclosed is a sensor comprising a sensor element that detects a measurand, the sensor element being in electrical contact with a sensor circuit that processes values derived from data from a secondary coil and/or from the measurand. The sensor circuit is in electrical contact with an ex-circuit. The sensor circuit is supplied a maximum input voltage and a maximum input current. The ex-circuit includes the secondary coil that receives an electrical signal from a primary coil. The electrical signal includes the data that are modulated onto the electrical signal. The sensor also includes a voltage limit that limits the voltage of the electrical signal to the maximum input voltage of the sensor circuit and a current limit that limits the current of the electrical signal to the maximum input current of the sensor circuit. Also disclosed are a sensor arrangement and a use of a sensor.