BS in Electrical Engineering
Electrical Engineering Department
The objective of this project is to familiarize the performers with the principles of operation of the Schweitzer Engineering Laboratories (SEL) protective relays in both normal and fault conditions. The SEL-587, SEL-311L and SEL-710 microprocessor-based relays are used to provide protection for a system composed of transformers, simulated transmission lines and a 3-phase induction motor. Each of these relays provides protection by sending a trip signal to local breakers upon sensing a fault condition. The SEL-587 provides overcurrent and differential protection for a 3-phase transformer, while the SEL-311L provides differential and distance protection for a transmission line, and negative sequence. The SEL-710 protects motors by monitoring the supplied current for locked rotor conditions, overcurrent, unbalanced phases, and undervoltage conditions and situations which would result in the motor overheating. This project involves testing the individual protective relays as well as incorporating all relays into a functional system, with independent regions of protection. That is to say that for fault in a given piece of equipment, the relay responsible for protection should be responsible for tripping the local supply breaker, providing protection in the event of a fault. The benefits of the lab are familiarization with protection schemes, the proper implementation of protection equipment and programming SEL relays and associated logic functions.