Monitoring and diagnosis of power as well as distribution transformer is the most important process for extending the life of transformer. A transformer monitoring system is already developed by Siemens which is based on SCADA system. But that system can’t be used in small scale industry because most of the industry lacks in automation. This paper presents the details of a monitoring system which is a standalone device equipped on every transformer individually and this device is able to detect phase failure, unbalanced voltage, and earth fault. Apart from these, the device can also monitor the oil level and oil temperature. The main aim of research is to develop this product and make available on economic rates.