Abstract:

Protection of three phase induction motor has been done using the microcontroller, overload relay and step down transformer. This protection scheme protects the three phase induction motor from unbalanced voltage source such as: under voltage, over voltage and over current. The overall process is monitored by microcontroller. Microcontroller sends signal through transistor to relay for operation. This microcontroller can sense 8 analog inputs up to 5V. Three analog inputs of microcontroller have been used for three phase voltages for conversion to digital signal. The remaining inputs can be used for receiving the information from motor such as temperature, speed etc. Step down transformer is (220V/12V). The output of these transformers will vary proportionately with respect to its input. The microcontroller senses the voltage, compares with the reference value and sends control signals to the respective protective relays. The overall system is cheap and reliable. It has been tes...