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About 4,817 papers for “Overcurrent”

Overcurrent and Directional Overcurrent Protection for Microgrid

Zahira Shiva Salsabila, Adrianti Adrianti, Muhammad Nasir · Andalasian International Journal of Applied Science Engineering and Technology · 2023

Microgrids will become common in future electrical distribution networks. Numerous operating modes that occur in microgrids make the development of protection schemes and settings challenging. This paper aims to develop a simple protection scheme for the Microgrid IEC Benchmark without any expensive equipment such as communication apparatus. The scheme consists of directional and non-directional overcurrent relays with standard inverse characteristics. For the simulation tool, Digsilent powerfactory is employed. Four operating modes of the microgrid are applied to verify the relays’ coordination. The results show that the proposed scheme successfully protects the microgrid during short circuit faults with acceptable time margins.

Cited by 1Open access

Overcurrent protection

Juan M. Gers, Edward J. Holmes · Institution of Engineering and Technology eBooks · 2011

Very high current levels in electrical power systems are usually caused by faults on the system. These currents can be used to determine the presence of faults and operate protection devices, which can vary in design depending on the complexity and accuracy required. Among the more common types of protection are thermomagnetic switches, moulded-case circuit breakers (MCCBs), fuses and overcurrent relays. The first two types have simple operating arrangements and are principally used in the protection of low-voltage equipment. Fuses are also often used at low voltages, especially for protecting lines and distribution transformers. Overcurrent relays, which form the basis of this chapter, are the most common form of protection used to deal with excessive currents on power systems. They should not be installed purely as a means of protecting systems against overloads which are associated with the thermal capacity of machines or lines since over current protection is primarily intended to operate only under fault conditions. However, the relay settings that are selected are often a compromise in order to cope with both overload and overcurrent conditions.

Cited by 0

Overcurrent Protection

Electric and Hybrid Vehicle Technology International · 2019

With the level of electrification in vehicles increasing, it is vital to ensure a high level of robustness in the fuses used in current and future electric and autonomous vehicles

Cited by 0

Overcurrent Relays

Tariq Masood, Jamil Abdo, Arshad Ali et al. · Power systems · 2025

Cited by 0

OVERCURRENT COORDINATION

2020

The objectives of protective device coordination is to achieve maximum selectivity without much sacrificing the sensitivity, though, by the very nature of the coordination, the fault clearance times toward the source will increase. Properly applied instantaneous overcurrent settings can be of help for fast fault clearance and arc flash hazard reduction. An initial analysis of the protection should reveal that none of the system components are exposed to damaging overloads or short-circuit currents, which will go undetected under various operating conditions. The sequential operation of series connected protective devices depends upon maintaining a minimum coordinating time interval throughout the operating range. The protective device data and characteristics are built in to the computer database. Coordination on instantaneous basis is a new frontier of much importance for arc flash hazard reduction. The selectivity is accessed from the time–current coordination curves of devices plotted to the same scale and noting down the overlaps.

Cited by 0

Overcurrent Switching Devices

2006

This chapter contains sections titled: Low voltage circuit-breakers MV circuit-breakers (according to standard IEC 62271–100) Low voltage fues MV fuses

Cited by 0

Modeling overcurrent relay characteristics

Steve Chan, R. H. Maurer · IEEE Computer Applications in Power · 1992

An approach to computer modeling of the time-current characteristics of protective devices that relies on interactive manipulation and fitting of the curves, which are modeled mathematically as splines is presented. The approach is much easier to use than the commonly used curve-fitting methods, which are reviewed, and it does not require a digitizer. It has been applied successfully in a PC-based short-circuit and relay coordination program for overcurrent relays, fuses, and reclosers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Cited by 12

EPROM-based overcurrent relays

K. Balasubramanian · 1992

A very simple and inexpensive time-overcurrent relay is reported. The relay is implemented using EPROM, a binary counter, a digital to analog converter, an analog comparator, and logic gates. As an extension of the work, the implementation of a multicurve time-overcurrent relay is reported. The switching of only four relays has been considered in this implementation. If required, the implementation can be expanded to accommodate more curves by increasing the EPROM memory area and the associated hardware. The system can be converted to handle multiple independent overcurrent relays by providing more comparators and associated control logic.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Cited by 2

Coordinating overcurrent protection devices

M. St. John, Alberto Borgnino · IEEE Computer Applications in Power · 1996

Distribution, substation, and plant engineers can benefit from using an overcurrent protection program in commercial, industrial, and utility applications to aid in clearing temporary faults and isolating permanent faults. In the time it normally takes to check one coordination scheme manually, dozens of alternatives can be evaluated using a graphics-oriented program, because the engineer receives immediate feedback for quick decision-making. It is well known that accurately coordinating overcurrent protection devices can minimize or prevent equipment damage, and electrical power service to customers can be greatly improved. In addition to assisting experienced engineers, an overcurrent protection program is an excellent training tool for new engineers. One such tool, V-PRO II, is a second generation program that is Windows-based. An extensive protective device library and an interactive on-line diagram for direct data entry are key new features. Easily identifiable icons are used along with pop-up menus and dialog boxes to simplify command selection. HELP can be accessed any time, and information on a specific topic can be retrieved quickly using hypertext. The program contains two separate windows: a one-line diagram with symbols for buses, lines, components, and protection equipment; and a time-current worksheet with time-current characteristic curves for both phase and ground coordination.

Cited by 3

Generator Backup Overcurrent Protection

David S. Baker · IEEE Transactions on Industry Applications · 1982

A concern that the characteristics and correct application of the generator backup relay are misunderstood is addressed in this report to the Power Systems Protection Committee. It is inherently a secure device, and rarely has the opportunity to operate in its intended capacity. So the question was asked, ``Do generator backup overcurrent relays really protect anything?'' In response a description of the function and operating characteristics of the backup relays, a discussion of generator fault current behavior, examples of relay settings for a typical application, and methods and criteria for determining that the relay both protects the generator and operates selectively with other protective devices are included.

Cited by 20