Side Menu
Recent Posts


Temperature Measurement at High Voltage

When temperature measurement at high voltage is to be made using Pt100 resistance thermometers, standard temperature transmitters are often unsuitable due to their insufficient insulation. Resistance thermometers can be insulated against high voltage. In practice, however, the available installation space is often too small. Moreover, the insulation is weakened by thermal and mechanical aging.


For temperature measurement at high voltage on power electronics components, maximum safety is therefore provided by high-voltage resistant galvanic isolation. A typical application is the monitoring of the winding temperature of electric motors, generators or transformers.


High-voltage motors as used in the process industry for fan, pump and compressor applications often carry out their service for years and decades without complaint. To monitor the temperature of high voltage motors, insulated temperature sensors are installed between the windings of each motor phase. Often, these motors are operated for decades. Transient overvoltages from the power supply, voltage surges caused by reflection, or continuous mechanical and thermal loads can damage the insulation. In that case, the high motor voltage will be transmitted via the sensor line. Conventional temperature transmitters are not protected against these high voltages which, although occurring very rarely, can cause considerable damage to downstream systems and to the persons working on them.


Our ProLine P 44000 temperature transmitter captures the signal from the temperature sensors and galvanically isolates and converts it into a standardized 4 to 20 mA signal, which is then transferred to the control system. Because the galvanic isolation is extremely robust, the basic insulation can withstand continuous working voltages of up to 6.6 V AC/DC and – depending on the supply type – be used for high-voltage motors up to 11 kV.


In this way, the ProLine P 44000 Pt100 transmitter reliably prevents redirection of the high motor phase potential caused by insulation defects in the sensor area.


Please visit ProLine P 44000 video for detailed information