A Simple and Low-Cost Equipment for Derating the Power Distribution Transformers Subjected to Distorted Operating Currents

The paper suggests a simple and affordable device that allows the fast and continuous in-situ calculation of operating parameters of the in-service distribution transformers that supply nonlinear loads. The proposed equipment is a system with an architecture based on two interconnected modules, mainly realized of electronic boards. The first one monitors and acquires the current power quality parameters at low-voltage part of the investigated transformer along with the ambient temperature. The second module performs the data processing, analysis, and results visualization. The computing algorithms for the transformer derating parameters consider the international recommendations. They are implemented in the developed device by using a dynamic programming language allowing a proper programming of the electronic boards. Accordingly, the equipment manages to preserve the transformer well-operating parameters, maintaining the continuity of energy supplied to nonlinear consumers. Supplementary, the device has low costs, is very flexible (suitable for transformers with rated power up to 2000 kVA) and can be easily adapted for remote data transmission.