The effects of three-phase harmonics

The effects of three-phase harmonics on circuits are similar to the effects of stress and high blood pressure on the human body. High levels of stress or harmonic distortion can lead to problems for the utility's distribution system, plant distribution system and any other equipment serviced by that distribution system. Effects can range from spurious operation of equipment to a shutdown...

HIGH-VOLTAGE (HV) TRANSMISSION LINE PROTECTION SCHEMES

Most transmission lines are protected by directional distance relays. These may serve as backup protection to other schemes in service, or these may be the sensing components in various forms of differential protection. Figure below shows the basic elements of a PLC (power line carrier)...

String Effeciency and methods to improve String Effeciency

The ratio of voltage across the whole string to the product of number of discs and the voltage across the disc nearest to the conductor is known as string efficiency i.e.,   String efficiency is an important consideration since it decides the potential distribution along the...

Voltage ranges

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Synchronization process

There are five conditions that must be met before the synchronization process takes place. The source (generator or sub-network) must have equal line voltage, frequency, phase sequence, phase angle, and waveform to that of the system to which it is being synchronized.   Waveform and phase sequence are fixed by the construction of the generator and its connections to the system....

Sizing of protective earthing conductor

Below is based on IEC 60364-5-54. This table provides two methods of determining the appropriate c.s.a. for both PE or PEN conductors.     c.s.a. of phase conductors Sph (mm2) Minimum c.s.a. of PE conductor (mm2) Minimum c.s.a. of ...

Earthing Systems

Panel boards are selling several Countries then earthing systems and main Bus bar arrangement are changed each country. Type of System Earthing 01.  TN system: TN power system have one point directly earthed, the exposed conductive parts of the installation being connected to that point by protective conductors. Three types of TN systems are recognized, according to the...

DOL starter

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Commercial and Industrial Power distribution systems

Power distribution systems used in multi-family, commercial, and industrial facilities are more complex. A power distribution system consists of metering devices to measure power consumption, main and branch disconnects, protective devices, switching devices to start and stop power flow, conductors,...

Power outage

A power outage (also power cut, blackout, brownout, or power failure) is a short- or long-term loss of the electric power to an area. There are many causes of power failures in an electricity network. Examples of these causes include faults at power stations, damage to electric transmission lines, substations or other parts of the distribution system, a short circuit, or the overloading...

Brownout

A brownout is an intentional or unintentional drop in voltage in an electrical power supply system. Intentional brownouts are used for load reduction in an emergency.[1] The reduction lasts for minutes or hours, as opposed to short-term voltage sag or dip. The term brownout comes from the dimming experienced by lighting when the voltage sags. A voltage reduction may be an effect of disruption...

SF6 gas & advantages

SF6 Advantages   The electric power industry has been using Sulfur Hexafluoride (SF6) gas as a dielectric and insulating material for many years. Its popularity is mainly due to its unique physical and electrical properties including: 1) Dielectric strength twice that of air. 2) Nontoxic, nonflammable and noncorrosive. 3) Chemically stable with high breakdown...

Load shedding (rolling blackout)

Load shedding is an intentionally engineered electrical power shutdown where electricity delivery is stopped for non-overlapping periods of time over different parts of the distribution region. Rolling blackouts are a last-resort measure used by an electric utility company to avoid a total blackout...

Base current rating table

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Residual-current device

RCDs are designed to disconnect the circuit if there is a leakage current. By detecting small leakage currents (typically 5–30 milliamperes) and disconnecting quickly enough (<30 ms), they may prevent electrocution. There are also RCDs with intentionally slower responses and lower sensitivities,...

FACTORS GOVERNING THE CURRENT RATING

The current rating of a cable or wire indicates the current capacity that the wire or cable can safely carry continuously. If this limit, or current rating, is exceeded for a length of time, the heat generated may burn the insulation. The current rating of a wire is used to determine what size is needed for a given load, or current drain. The factors that determine the current rating of a...

Types of Hydropower Turbines

There are two main types of hydro turbines: impulse and reaction. The type of hydropower turbine selected for a project is based on the height of standing water—referred to as "head"—and the flow, or volume of water, at the site. Other deciding factors include how deep the turbine must be set,...

Busbars And Their Uses

Used in electrical power distribution, busbars are usually made out of aluminium or copper and they are able to conduct electricity to transmit power from the source of electric power to the load. They are usually supported by insulators and conduct electricity within switchboards, substations or other electric apparatus. Some typical applications of these devices can be to form the interconnectedness...

Busbars And Their Uses

Used in electrical power distribution, busbars are usually made out of aluminium or copper and they are able to conduct electricity to transmit power from the source of electric power to the load. They are usually supported by insulators and conduct electricity within switchboards, substations or other electric apparatus. Some typical applications of these devices can be to form...

DC motor types

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Advantages & disadvantages of energy saving bulbs

Energy saver light bulbs are highly energy efficient. You can find a wide range of energy efficient products in the market. However during the time when they were introduced in the market they were available in big sizes and did not have unique designs. Moreover they were costly and took a considerable time to reach full brightness. With the advanced technology the energy light bulbs available...

DIFFERENTIAL PROTECTION

Differential protection is a very reliable method of protecting generators, transformers, buses, and transmission lines from the effects of internal faults. Figure: Differential Protection of a Generator In a differential protection scheme in the above figure, currents on both sides...

Hybrid cars

Hybrid cars are considered as major breakthrough in the vehicle technology progress. For long, vehicles that use gasoline or some other fossil fuels have been running on the road. People have been familiar with such kind of vehicle, but more of them are aware with such fossil fuel engine performance...

Voltage sags

Voltage sags -- or dips typically lasting from a cycle to a second or so, or tens of milliseconds to hundreds of milliseconds. Voltage swells are brief increases in voltage over the same time range. (Longer periods of low or high voltage are referred to as "undervoltage" or "overvoltage".)...

Power system protection

Types of protection   Generator sets – In a power plant, the protective relays are intended to prevent damage to alternators or to the transformers in case of abnormal conditions of operation, due to internal failures, as well as insulating failures or regulation malfunctions. Such failures are unusual, so the protective relays have to operate very rarely. If a protective relay...