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Major Depressive Disorder (MDD) is a common health problem characterized by low mood, sadness and irritability. Sleep disturbances are a central feature of depression and adolescence is a period of rapid change in sleep physiology.To evaluate the categorization of sleep change in three of sleep elements : REM changes; Slow weave sleep changes and fragmentation of sleep. We evaluated this as a tool...
This paper focuses on considerations and field experiences while testing a typical multifunctional generator protection IED. The comprehensive generator testing is classified in four major stages: 1) certification/functional/type testing; 2) commissioning; 3) periodic maintenance; and 4) troubleshooting. First of all, the paper presents different aspects of the certification/ functional testing, and...
Transient single-phase short circuits are the most common transmission line faults. The short circuit arc of a transient fault is usually self-extinguishing after opening the line circuit breakers. High-speed single-phase reclosing of transmission line can help to improve system stability. Employing a pre-set reclosing interval may pose problem if the time interval is not sufficient to fully deionize...
This paper presents an operational experience with incipient faults: it has been observed that 10 to 15% of cable faults are preceded by incipient faults. Practically all incipient faults become permanent faults in the period between a few seconds to few weeks. Incipient faults occurring in fast successions create considerable overvoltages and induce faults on other feeders. A method has been presented...
Before 2003 blackout, protection engineers didn't pay much attention to this phenomenon; it was not even part of relay acceptance testing. However, multiple nuisance trips during this blackout, forced system operators to look at this problem and re-evaluate relay performance for such conditions. In fact, Federal Energy Regulatory Commission (FERC) has appealed to the IEEE Power System Relaying Committee...
The computational capabilities of numerical relays allow the development of sophisticated overcurrent algorithms. These algorithms ensure dependable and fast operation of short circuit protection even under severe saturation of current transformers. This eliminates the need for impractical engineering of such applications, and increases confidence levels in cases with relatively well-rated CTs that...
This paper presents an operational experience with incipient faults: it has been observed that 10 to 15% of cable faults are preceded by incipient faults. Practically all incipient faults become permanent faults in the period between a few seconds to few weeks. Incipient faults occurring in fast successions create considerable over-voltages and induce faults on other feeders. A method has been presented...
This paper addresses re-strike conditions of breakers connecting capacitor banks. Field cases are presented as related to both breaker failure and breaker re-strike conditions. A method has been presented for detecting re-strike of a breaker connecting capacitor banks. The method has been implemented and tested using both field cases and by real time digital simulation. The re-strike detection function...
This paper presents balance equations for ultra-sensitive protection of shunt capacitor banks taking into account both an inherent (pre-existing) unbalance in the protected bank, and an unbalance in the power system. Four methods are derived: voltage differential, neutral voltage unbalance, phase current unbalance, and neutral current unbalance. These methods are generalizations of the known protection...
This paper discusses several protection and control aspects in relation to dual-breaker line terminals. First, breaker failure and reclosing functions are discussed as applied to dual-breaker configurations. Second, the paper talks about protection security as related to saturation of current transformers (CTs) under fault currents flowing locally through the two breakers. New generation of microprocessor-based...
More and more often series compensation, non-standard generation and power electronic devices co-exist in a vicinity of EHV transmission lines. A typical scenario is a relatively long transmission line already with elements of HVDC and/or series-compensation, interconnected to a new wind farm with significant capacity driven by non-standard machines. In some cases single-pole tripping is applied in...
Line protection in breaker-and-a-half configurations requires main protection functions to respond to the sum of the two currents. This concerns many protection functions particularly when sensitive settings are applied and/or significant Ct saturation occurs. If the remote system is relatively weak, the current supplied through the line towards a close-in reverse fault on the breaker-and-a-half terminal...
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