Rimu Cable Co., Ltd.

Sometimes, for convenience and to save space, temperature compensation wires and power cables are installed in the same conduit. But does this affect the accuracy of the displayed temperature?

In general, the electrical resistivity of metal conductors increases as the temperature rises, which can affect the accuracy of the heat-source temperature measured by a temperature sensor. To achieve higher measurement accuracy, the temperature signal detected by the sensor is typically amplified by an operational amplifier before being displayed. Therefore, the wiring between the temperature sensor and the amplifier in the digital temperature display is also susceptible to external interference.

First, the resistance of the wire itself changes with temperature, which can affect measurement accuracy. For this reason, temperature compensation wires should be used in this section to minimize the impact of ambient temperature changes on measurement results. If temperature compensation wires and power cables are routed together, the temperature signal may be affected by AC electromagnetic interference. When the current in the power cable fluctuates suddenly, the resulting electromagnetic interference may enter the operational amplifier and cause an incorrect signal to be displayed. In addition, routing temperature signal wires alongside power cables can create significant inter-wire capacitance. This capacitance may transmit high-frequency electromagnetic interference generated by rapid changes in AC power to the amplifier, causing the temperature measuring device to display an incorrect temperature signal.

Therefore, to prevent erroneous measurement signals, temperature compensation wires and power cables should be routed separately, and appropriate shielding measures should be implemented. In addition, all connections and welded joints between the thermocouple and the display should be properly made, as improper connections may also affect the accuracy of the detected temperature signal.