Blog Posts on protective relaying




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EFFECTS OF LOAD ON TRANSMISSION LINE RELAY APPLICATIONS AND SETTINGS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Dec 11, 2012One of the principal influences on protective relay settings is load; hence, maximum load current level, in turn, may influence fault detection sensitivity. Phase overcurrent relays Phase overcurrent relays must be set to avoid operation on all...



PROTECTIVE RELAY COORDINATION BASICS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Nov 16, 2012Coordination is a systematic application of current actuated devices in a power system, which in response to a fault or overload will remove only a minimum amount of equipment from service. The objective is to minimize the equipment damage. A coo...



DIFFERENTIAL RELAY PURPOSE AND FUNCTIONS BASIC INFORMATION by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Nov 15, 2012How Differential Relay Protect Your System? Differential relays provide high-speed (1 to 2 cycles), sensitive, and inherently selective protection. These will not provide protection for turn-to-turn winding faults in generators, motors, and transf...



TYPICAL GENERATOR PROTECTIVE DEVICES AND RELAYS BASIC INFORMATION by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Nov 10, 2012The protective functions noted in the various generating station configurations provide both primary and backup protection for the generating station as well as additional protection schemes which could also be applied. These protective functions...



DELAYED AUTORECLOSING POWER DISTRIBUTION PRACTICE BASIC INFORMATION by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Nov 10, 2012Delayed autoreclosing may need to be considered when the upstream protection is provided by electromechanical relays or fuses and the circuit protection is provided by microprocessor-based relays, unless the microprocessor-based relays can be set to...



POWER SYSTEM PROTECTION DESIGN CRITERIA BASIC INFORMATION by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Oct 31, 2012The logic of protective relaying looks at a complex distribution system as an integration of various subsystems. In all cases, some common design criteria are applicable. This consists of five basic elements: (1) selectivity, (2)speed of operation...



PRIMARY AND BACK UP PROTECTION OF TRANSMISSION LINES BASIC AND TUTORIALS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on Jun 16, 2012The main protection system for a given zone of protection is called the primary protection system. It operates in the fastest time possible and removes the least amount of equipment from service. On Extra High Voltage (EHV) systems, i.e., 345kV an...



DIFFERENTIAL RELAYING WITH OVERCURRENT RELAYS BASIC AND TUTORIALS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on May 23, 2012Differential relaying with overcurrent relays requires connecting current transformers in each phase of each circuit in parallel with an overcurrent relay for that phase. (See Fig 1, illustrating the connections for 1 phase of a 3-phase system.)...



SYNCHRONOUS GENERATOR STATOR WINDING GROUND FAULT PROTECTION BASIC AND TUTORIALS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on May 19, 2012Protection against stator-to-ground fault will depend to a great extent upon the type of generator grounding. Generator grounding is necessary through some impedance in order to reduce the current level of a phase-to-ground fault. With solid gener...



SYNCHRONOUS GENERATOR LOSS OF EXCITATION PROTECTION BASIC AND TUTORIALS by TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB on May 19, 2012A loss-of-excitation on a generator occurs when the field current is no longer supplied. This situation can be triggered by a variety of circumstances and the following situation will then develop: 1. When the field supply is removed, the generator...