INTRODUCTION
Distance relaying is a form of protection against faults on long-distance power lines. Distance protection is the name given to the protection, whose action depends upon the distance of the feeding point to the fault. It is so named because it is actually able to estimate the physical distance between the relay’s sensing transformers (potential transformers and current transformers) and the location of the fault. In this way, it is a more sophisticated form of fault detection than simple overcurrent protection. In engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected.
Microprocessor-based digital protection relays now emulate the original devices, as well as providing types of protection and supervision, impractical with electromechanical relays. Electromechanical relays provide only rudimentary indication of the location and origin of a fault. In many cases, a single microprocessor relay provides functions that would take two or more electromechanical devices. By combining several functions in one case, numerical relays also save capital cost and maintenance cost over electromechanical relays. The transmission and sub-transmission lines play an essential role in the distribution of electrical power to the end users. They provide connections between the generation and distribution system. Transmission lines operate at voltage levels from 33kV to 330kV and are tightly interconnected for reliable operation. The theory and application of these protective devices is an important part of the education of a power engineer who specializes in power system protection. The need to act quickly to protect circuits and equipment often requires protective relays to respond and trip a breaker within a few thousandths of a second.
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Commissioning of the MICOM P443 Main 2 Distance Protection Relay on Ayede-Osogbo 330kV Transmission Line
