Protection
An example of transformer overload and short circuit protection
Transformer protection consists of both overload protection and short circuit protection. Overload protection is usually accomplished via proper selection of the secondary overcurrent protective device. NEC Article 450 gives specific primary and secondary overcurrent device ratings that may not be… Read more
Jan 21, 2015 | By Edvard Csanyi
Protection
Lightning and surge protection of multi-megawatt wind turbines
There is an unabated trend for the utilisation of regenerative energy gained from wind turbines, solar, photovoltaic and biogas plants or geothermal heat. This is an enormous market potential not only for the energy industry but also for the suppliers and the electrical… Read more
Dec 19, 2014 | By Edvard Csanyi
Energy and Power
Danger And Control Of Static Electricity Buildup
It is necessary to study the static buildup potential of any workplace and institute protective measures to control such buildup. The following are the dangers posed by static electricity: Ignition causing fire or explosion Damage to sensitive electronic components Electric… Read more
Dec 12, 2014 | By Edvard Csanyi
Energy and Power
When customer complains on equipment failure caused by overvoltage…
While voltage sags and momentary interruptions cause the most widespread power quality problems, several other power quality disturbances can damage equipment, overheat equipment, disrupt processes, cause data loss, and annoy and upset customers. Often, customers complain of equipment failures, especially… Read more
Nov 17, 2014 | By Edvard Csanyi
Energy and Power
4 essential qualities of electrical protection
In generating stations, all electrical circuits and machines are subject to faults. A fault is generally caused by the breakdown of insulation between a conductor and ground or between conductors due to a variety of reasons. The result is a… Read more
Nov 03, 2014 | By Edvard Csanyi
Energy and Power
Applications and characteristics of differential relays (ANSI 87)
Differential relays generally fall within one of two broad categories: Current-differential and High-impedance differential Current-differential relays are typically used to protect large transformers, generators, and motors. For these devices detection of low level winding-to-ground faults is essential to avoid equipment damage. Current… Read more
Oct 29, 2014 | By Edvard Csanyi
Energy and Power
Let’s analyse phase-to-earth faults in a single-incomer power system
Power-system protection should detect faults and isolate the faulty parts of the power system while keeping the fault-free parts in operation. Protection units are chosen according to the power-system configuration (parallel operation of generators or transformers, loop or radial power system,… Read more
Oct 17, 2014 | By Edvard Csanyi
Energy and Power
An example of the effectiveness of directional overcurrent relays (ANSI 67, 67N)
When fault currents can flow in more than one direction with respect to the load current it is often desirable to determine which direction the fault current is flowing and trip the appropriate devices accordingly. This is usually due to the need… Read more
Oct 10, 2014 | By Edvard Csanyi
Energy and Power
Applications and characteristics of overcurrent potection relays (ANSI 50, 51)
Overcurrent relays are the most commonly-used protective relay type. Time-overcurrent relays are available with various timing characteristics to coordinate with other protective devices and to protect specific equipment. Instantaneous overcurrent relays have no inherent time delay and are used for fast short-circuit… Read more
Oct 08, 2014 | By Edvard Csanyi
Energy and Power
14 terms of particular importance when discussing arc flash hazards
Electrical arcs form when a medium that is normally an insulator, such as air, is subjected to an electric field strong enough to cause it to become ionized. This ionization causes the medium to become a conductor which can carry current. The… Read more
Sep 10, 2014 | By Edvard Csanyi
Energy and Power
Rating Definitions Applied to Medium Voltage Circuit Breaker
The medium voltage circuit breaker is the device of choice when sophisticated system protection at the medium voltage level is required. Most modern medium voltage circuit breakers use a vacuum as the interrupting means, although sulfur-hexafluoride (SF6) based units still exist and in use. Medium… Read more
Sep 03, 2014 | By Edvard Csanyi
Energy and Power
10 most common power disturbances that make our life difficult
As you know, deviation from sinusoidal form at the nominal voltage level is actually a power quality issue or power disturbance, defined as “any deviation from the nominal value (or from some selected thresholds based upon tolerance) of the AC… Read more
Aug 22, 2014 | By Edvard Csanyi
Energy and Power
How to get rid off the harmonics in electrical system?
The subject of harmonics is also a contributory factor in electrical noise I already wrote few days ago (Cable spacing as a means of noise mitigation). It also causes several other problems in power circuit components such as motors, transformers and capacitor… Read more
Jul 16, 2014 | By Edvard Csanyi
Medium Voltage
Microprocessor and conventional secondary systems compared
Secondary systems are all those facilities needed to ensure reliable operation of the primary system, e.g. a high voltage substation. They cover the functions of controlling, interlocking, signalling and monitoring, measuring, counting, recording and protecting. With conventional secondary systems, the… Read more
Jul 09, 2014 | By Edvard Csanyi
Protection
Protection Against Overexcitation Of a Transformer
Overexcitation of a transformer means that the magnetic flux in the core is increased above the normal design level. This will cause an increase of the magnetizing current and the transformer can be damaged if this situation isn’t taken care… Read more
Jul 02, 2014 | By Edvard Csanyi
