I/O Module CJC Sensor Placement for Terminal Availability
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Solution Overview
Problem
Existing temperature input/output modules for industrial control systems face limitations when using thermocouples due to the need for cold junction compensation, which reduces the functionality of removable terminal blocks and increases costs, as embedded or external CJC sensors occupy terminal space and require special manufacturing and installation.
Innovation Solution
The I/O module design includes a CJC sensor connected to the I/O module base, which remains physically and operatively connected regardless of the removable terminal block's position, allowing for accurate cold junction compensation without reducing terminal block functionality or increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CJC sensor is embedded within the removable terminal block (RTB), then cold junction compensation can be achieved, but the functionality of the RTB is reduced because terminals are dedicated to the CJC sensor
Solution Approach 1:
The CJC sensor is extracted from the removable terminal block and repositioned on the I/O module base. This separation allows the RTB to use all its terminals for field wiring connections while the CJC sensor remains connected to the base through dedicated contact pairs, resolving the conflict between CJC functionality and terminal availability.
Solution Approach 2:
The I/O module base serves as an intermediary between the RTB and the CJC sensor. The base contains the CJC sensor and provides dedicated contact pairs that electrically connect the sensor to the I/O circuitry, while the RTB remains a separate, fully functional terminal block for field connections.
2Reliability
If an external CJC sensor is connected to the RTB terminals, then cold junction compensation is achieved, but the RTB requires two contact pairs to operatively connect the sensor
Solution Approach 1:
The CJC sensor is merged with the I/O module base structure, becoming an integrated component rather than a separate external element. The sensor, its mounting structure, and its electrical connections are all combined on the base, eliminating the need for separate RTB contact pairs and reducing overall system complexity.
3Measurement precision
If the CJC sensor is connected to the RTB, then temperature sensing is achieved, but the sensor moves with the RTB when separated from the base
Solution Approach 1:
The system is segmented into three distinct components: the RTB for field connections, the CJC sensor for temperature measurement, and the I/O module base that integrates both. The sensor is electrically connected to the base through dedicated contact pairs, ensuring stable electrical connection independent of RTB positioning or removal.
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 design enhances the functionality of the removable terminal block by maintaining CJC sensor connection to the I/O module base, ensuring accurate temperature compensation for thermocouples while preserving terminal availability and simplifying manufacturing and installation processes.
Implementation Method 1
The first CJC sensor is connected to the I/O base and is operatively connected to the I/O circuitry. The first CJC sensor is operatively associated with and adapted to sense a temperature of at least a first one of said second constituent contacts.
Data Source
AI summary
An I/O module includes an I/O base comprising a printed circuit board including I/O circuitry. A removable terminal block is removably connected to and selectively separable from the I/O base. The removable terminal block includes a plurality of field wiring terminals. The I/O module further includes a plurality of contact pairs each including: (i) a first constituent contact connected to the removable terminal block and electrically connected to one of said terminals; (ii) a second constituent contact connected to the I/O base and electrically connected to the I/O circuitry. A first CJC sensor is connected to the I/O base and is operatively connected to the I/O circuitry. The first CJC sensor is thermally associated with and adapted to sense a temperature of at least a first one of said second constituent contacts.