Managing Distributed Temperature Measurements in an Embedded System of a 3-Phase 10 kVA Energy Efficient Switchable Distribution Transformer Employing a Modular Approach

Temperature measurements are one of the most significant factors in condition monitoring and protecting transformers as well as estimating their life expectancy. With switchable transformers, it is also significant to carry out temperature monitoring to protect the switching devices. This paper presents techniques to manage temperature measurements of the windings and core of a 3-phase 10kVA switchable distribution transformer as well as switching devices that connect the tappings of the transformer. Serial digital temperature sensors DS18S20 were utilized to read the temperatures of all intended points which were distributed around the transformer and switching devices. Multi-drop connections through 1-Wire® buses were implemented to interface the sensors with some micro controllers which were located in some separated modules. Furthermore a Controller Area Network (CAN) bus was used to enable the exchange of measurement results between the modules. Software has also been developed to follow a previously developed protocol for communication through the CAN bus. From testing results, it could be shown that the techniques could be implemented by using the embedded system to achieve reliable distributed temperature measurements for the transformer and switching devices. In addition, results of the measurements reveal that the implementation of a parallel configuration of the windings at high loads reduces losses caused by the windings, which in turn improves the efficiency of the transformer.