Meaning
A multi-point temperature measurement configuration utilizing resistance temperature detectors provides highly accurate, distributed thermal profiling across a planar surface. In environmental chambers and hardware-in-the-loop test benches, an rtd sensor array monitors temperature variations across electronic boards and heat sinks during power cycles. This array delivers precise data from multiple nodes, enabling the detection of localized hot spots that could compromise the reliability of the system.
The high stability and repeatability of the sensor elements ensure that the collected thermal data is reliable over long testing durations.
Array Layout
Positioning the sensors across the board requires careful consideration of the expected heat sources and thermal paths. High-power components such as processors and power transistors are monitored directly by placing sensor nodes in close physical proximity to their packages. The sensors are arranged in a grid pattern to capture the overall thermal gradients and map the flow of heat from the sources to the exhaust vents.
This layout provides the necessary spatial resolution to validate the thermal models of the enclosure.
Signal Conditioning
Measuring the small resistance changes of the sensor elements requires specialized analog circuitry to convert the resistance into a readable voltage. Each sensor is typically integrated into a four-wire bridge circuit to eliminate the effects of lead wire resistance on the measurement. The signals are then routed through a multiplexer to a high-resolution analog-to-digital converter, which digitizes the data for the controller.
This configuration minimizes noise pickup and ensures high measurement sensitivity across all active channels.
System Calibration
Calibration is performed before deploying the assembly to ensure that individual sensor variations do not introduce measurement errors. The array is placed in a uniform thermal bath and the resistance of each sensor is measured at multiple reference temperatures. These readings are used to calculate the Callendar-Van Dusen coefficients for each sensor, which are then stored in the system’s calibration database.
During operation, these coefficients are applied to the raw resistance readings to calculate the true temperature of each node. This systematic tuning process is repeated annually to account for the natural aging and long-term drift of the platinum elements, which ensures the continuous validity of the test data collected during product lifecycles. The resulting certificate of calibration documents compliance with standard laboratory quality guidelines and ensures the test system’s legal metrological traceability.
