Which Class of Wire need to be used for House Wiring

Different Class of Conductor

• As per IEC 60228, Electrical wires/cables are classified into different classes according to the conductor’s flexibility, conductor hardness & thermal effects.
• There are four classes of flexibility for electrical cables
• Class 1 = Solid conductor= ideal conductors for permanent installations.
• Class 2 =Stranded conductor= conductors designed for fixed installation.
• Class 5 =Flexible conductor= preferred to used where flexibility is required, for movable equipment , where there is vibration in equipment.
• Class 6 =Very Flexible conductor= highly flexible conductors used in robotics, flexible codes.
• Classes 3 and 4 are not described in IEC 60228.
• The most basic type of conductor is a single, solid wire (Class 1). It provides a smaller diameter, the largest Cross-Sectional Area (CSA), and the clearest signal, it is mechanically fragile and susceptible to breakage after repeated bending cycles.
• To improve flexibility, wires are stranded together (Class-2, Class-5, Class-6). Class 2 is a multi-wired conductor, while classes 5 and 6 are fine or ultra-fine wired conductors. The IEC standard specifies values such as the maximum diameter and maximum resistance for the individual wires.
• The more wires that are stranded together to make a given size, the more flexible the conductor will be. This indicates that a higher class corresponds to a greater number of strands within the conductor. Additionally, stranded wires are significantly easier to manipulate and bend during installation compared to a single wire of equivalent cross-section.
• Classes 1 and 2 are intended for use in cables for fixed installations. On the other hand, Classes 5 and 6 are designed for use in flexible cables and cords but may also be used for fixed installations.

(A) Class 1: Solid Conductors

• Construction: Single Conductor, solid copper wire.
• Flexibility: Rigid and non-flexible. the cable should not be bent more than about four times its diameter
• Characteristics: High electrical conductivity and resistance to corrosion, but less suitable for environments requiring flexibility.
• Advantages: Less expensive than cables with multiple wires
• Disadvantages: Less suitable for applications involving movement.
• Heat and Losses: Class 1 wires are more efficient for fixed wiring due to lower resistance and heat generation. 
• Applications: Typically used in permanent, stationary installations, House wiring where the conductor will not be subject to frequent movement or low flexibility is not a problem such as in building wiring and power distribution.
• They are often used when cables with larger cross-sections are required for fixed installations. They are not suitable for very flexible cables, which are used, for example, in continuously moving objects such as robotic arms in industrial production

(B) Class 2: Stranded Conductors

• Construction: Composed of multiple smaller copper wires twisted or braided together to form a single conductor.
• Flexibility: More flexible than Class 1, allowing for some movement without breaking or damaging the wire.
• Characteristics: Offers a balance of flexibility and durability but may not be as conductive as a solid conductor of the same gauge.
• Advantages:Lower electrical resistance and less heat buildup under load.
• Disadvantages:Less suitable for applications involving movement.
• Heat and Losses:Class 2 wires are more efficient for fixed wiring due to lower resistance and heat generation. 
• Applications: Primarily used for fixed installations like permanent building and house wiring and for industrial applications with increased cable flexibility requirements.

(C) Class 5: Flexible Conductors

• Construction: Consists of many fine copper wires (often tinned for corrosion resistance) twisted together, making the conductor highly flexible.
• Flexibility: Extremely flexible, designed for applications where the conductor needs to withstand frequent movement, bending, or vibration without damage.
• Characteristics: High flexibility, durable against wear and tear, but may have slightly lower conductivity compared to solid conductors due to the finer strands.
• Advantages:Superior flexibility.
• Disadvantages:Higher electrical resistance, which can result in greater heat loss and voltage drops.
• Heat and Losses:Class 5 wires are not efficient for fixed wiring due to higher resistance and heat generation compared to Class-2. 
• Applications: Used in situations where more flexibility is required, such as in circuits that may need to be bent, coiled, or moved occasionally. Ideal for portable appliances and equipment that move constantly like portable cords, flexible cables, and power tools that require a durable, yet highly flexible conductor.

(D) Class 6: Extra Flexible Conductors

• Construction: Made up of very fine copper wires, typically tinned, twisted into a very flexible configuration.
• Compared to class 5, the number of strands and wires arranged around each other is even larger, which can further increase the flexibility of the wire
• Flexibility: The highest level of flexibility among copper conductors, suitable for applications requiring frequent movement or twisting.
• Characteristics: Very high flexibility, ideal for dynamic applications, but may have lower conductivity due to the fine strands.
• Applications: Used in highly flexible cable assemblies, robotics, automobile, machine and tool construction and flexible power cables where the conductor will experience constant movement and mechanical stress.

Which Class of Conductor Used for House hold Wiring:

• To reduce power consumption, eliminate heating of wires, The Selection of House wire is most important.
• The selection of Wires broadly depends on conductor Resistance, Current, Quality of conductor material, Cross section area and power consumption.
• Resistance: A conductor with higher resistance will consume more power (P = I²R, where P is power, I is current, and R is resistance).
• Current: If both conductors are used in the same application with the same current, the one with the higher resistance will consume more power.
• Conductor Quality: Many people believe that wire quality simply by measuring its diameter and doing a mathematical calculation to estimate resistance. Conductor resistance is not just about the size of copper but it also depends on copper purity. For example, impure or recycled copper may have a bigger cross-sectional area but still higher resistance, which means more heat, more energy loss and shorter wire life.
• Conductor Size: The material (copper, aluminum, etc.) and the cross-sectional area of the conductor also significantly affect resistance and power consumption.
• Power Consumption: The power consumption of a conductor is primarily determined by its resistance and the current flowing through it, rather than its classification (Class 2 or Class 5). However, the classification itself does provide some context regarding the conductor’s characteristics:
• There are mainly two types of Conductors solid (Class-1) and stranded (Class-2 & Class-5).

(A) Selection between Class-1 or Class-2 (Solid or Standard):

• Solid conductor (Class-1) has less flexibility hence not easily passing in conceal conduits of house wires and making hot spots at conductor bends. Due to less flexibility easily break conductor at its termination location.
• The cables used in Building wiring switched to Class 2 copper conductors as it offered better flexibility over the Class 1 solid copper conductors. It is also technically superior and avoid hot spots at bends without compromising the current carrying capacity on account of its resistance being the same as specified for Class 1 copper conductors.
• Multi-stranded conductor (Class-2) shall be replaced to single solid conductors (Class-1) for all the House wiring.

(B) Selection between Class-2 & Class-5 (Standard or fine Standard):

• Stranded conductor can be divided broadly in two types one is multi-strand conductor (known as class-2 conductor) other is Flexible stranded conductor (known as class-5 conductor).
• The difference between Class-2 & Class-5 Wires are as under
• Resistance: The conductor resistance of class 5 is high compared to class 2 conductor, the heat generated for the same current loading will be different on both class of conductors

Copper Conductor Resistance based on class (IS:694)
Wire Size	Copper Conductor Resistance (Ω/Km)		Insulation Thickness (mm)		Tensile Strength (N/mm2)
	CLASS-2	CLASS-5	CLASS-2	CLASS-5	CLASS-2	CLASS-5
0.75 Sq.mm	24.5	26	0.7	0.6	12.5	10
1 Sq.mm	18.1	19.5	0.7	0.6	12.5	10
1.5 Sq.mm	12.1	13.3	0.7	0.6	12.5	10
2.5 Sq.mm	7.41	7.98	0.8	0.7	12.5	10
4 Sq.mm	4.61	4.95	0.8	0.8	12.5	10

• Insulation: The insulation thickness for the class 5 conductor cable is lesser than specified for class 2, not better for higher load conditions
• Mechanical Strength: The mechanical strength of insulation for class 5 is lesser in comparison to class 2, this can lead to issues during conduit pull.
• Flexibility: The difference lies mainly in flexibility.
• Class 2 wires have fewer strands (Conductor) of more diameter. Example :14/0.31mm(max.) 14 strands each of 0.31 mm (max.). typically, 7 strands are used which makes them less flexible and more suitable for fixed installations.
• Class 5 wires have more strands (Conductor) of less diameter. Example: 32/0.21mm(max.) 32 strands each of 0.21 mm (max.). Typically, 30 to 50 strands are used, which makes them more flexible and easier to bend.
• Application: For fixed wiring application conductors with Class 2 copper shall be used. Worldwide the usage of class 2 conductors is specified for building wires as it offers lower resistance, mechanical strength is higher.
• Class 5 wires are commonly used in applications where flexibility is important, such as in portable appliances and equipment where the lengths are preferably 1.5 to 2-meter, power tools, panel wiring (As bending and routing of such cables in constricted paths do not stress on the cable and handling and installation of such conductors in confined areas is easier).
• Amount of Copper content: Actually, in class 5 conductors, copper content is less than that of class 2 conductor which make them more flexible wires. The reason is copper wires with class 5 conductor are cheaper.
• Lesser copper content in wire leads to increased cable resistance and which may in turn increase power consumption and loss. on the other side these coper wires with class 5 conductor can bring disaster in a building as it increases the disconnection time of protective device due to its increased resistance. The power loss of class 5 conductor is higher and is against the concepts of energy conservation or sustainability.

Comparison of Class 2 and Class 5 copper conductors
Property	Characteristic	CLASS-2	CLASS-5
Installation	Passing through Conduit	Easy to Pass through Conduits due to less flexible compared to Class-5	Conductor is more Flexible hence change of Cable getting Stuck in Conduit
	Termination	No of Strands are less hence easy to crip Lugs	No of Strands are higher hence difficult to hold all strand under Lugs while crimping
	Maintenance	In case of replacement easy to pull out Wire from Conduit	difficult to pullout from conduit after installation.
Mechanical	Tensile Strength	Higher mechanical Strength to withstand Stress	Mechanically weak compared to Class-2
	Loose Connection	Cable stay firm near its termination in case of vibration	Might get loose in case of vibration
	Conductor Roundness	Conductor bunch is circular due to less number of strands	Due to more no of Strands and it’s arrangement. Not circular as compared to class-2
	Conductor Structure	Fewer Strands (Conductor) of large Size	More Strands (Conductor) of Small Size
Electrical	Resistance	Less conductor Resistance	Higher Conductor Resistance
	Current Capacity	Higher Current carrying capacity	Less Current carrying capacity
	Derating Factor	Better conductor roundness makes symmetrical arrangement in conduit, reduce derating Factor	Higher derating Factor
	Amount of Copper	Use of Copper is higher than Class-5 for the Same Size of Conductor	Use of Copper is less than Class-2 for the Same Size of Conductor
	Power Loss	Less Power Loss due to less resistance	6 to 8% Higher Power Loss compared to Class-2
	Insulation	Insulation thickness is higher than Class-5	Insulation thickness is less than Class-2
	Heat Built up	Minimal (Due to less Resistance)	Heat Faster under Load
Cost	Cheaper	5 to 8% Costly (due to more Copper) than Class-5	Cheaper than Class-2
Application	Fixed /Movable	Typically used fixed / Permeant Wires installation in wall and ceiling where wires are permeant and used regularly	Used for Flexible application like Power cord, extension Wires Board, for Movable parts

• Multi-stranded conductor (Class-2) shall be used for house wiring due to its Less Resistance, Less heat loss, Low Power consumption, better insulation, higher mechanical Strength.

Conclusion:

• Actually, Wires with Class-5 copper are used for appliance wiring and panel wiring (Not Fixed Wiring) only and they are also manufactured accordingly. Wiring with Class-5 copper conductors do not conform to the code of practice of wiring and hence it’s illegal to use them in fixed wiring and In IS 694 specifies panel wire and building wire as a similar group of functioning. This created a confusion and an create opportunity to misuse of Class 5 conductors as building wires because Class-5 Wires are 8 % cheaper than wires with Class-2 copper conductor.
• However, we must avoid to use Class-5 Wires for Wiring Application due to its less copper content (due to its more flexibility) in wire will lead to increase cable resistance and which may in turn increase the power consumption, higher watt loss, higher voltage drops, higher fault loop impedance.
• Higher impedance of the circuit may lead to accidents due to higher disconnection time of protective device. Less mechanical strength, less insulation hence heats up in load and not safe in continuous load.
• For fixed wiring application, House Wiring conductors with Class 2 copper shall be used.

Power Quality

Power Quality:

• In the present scenario of power utilization and consumption, the importance of power quality is vital for a continuous and effective power supply. The features of power quality play a major role in the effective power utilization along with the control & improvement measures for various factors affecting it.
• Power quality is defined as the ability of a system to

1.     Deliver electric power service of sufficiently high quality so that the end-use equipment will operate within their design specifications and

2.     It should be of sufficient reliability so that the operator of end-use equipment will be continuous.

• In other words it may be defined as the concept of powering, grounding and protecting electric equipment in a manner that is suitable to the operation of that equipment.

Why is it a concern?

• Power Quality has been a problem since the conception of electricity, but only over the last 2 decades has it gotten considerable attention with the introduction of large numbers of computers & microprocessors in business and homes; and the network revolution and ever increasing equipment capability and speed.
• There are various factors that really make us think about it.

1.     Power quality problems can cause equipment malfunctions, excessive wear or premature, failure of equipment, increased costs, increased maintenance, repair time and expense & outside consultant expense.

2. Electronic equipments are more sensitive to minor fluctuations. We rely on the equipment more and have higher expectations. New electronic devices are more sensitive than the equipment being replaced as well.

Power Quality Affecting Factor:

• Many electronic devices are susceptible to power quality problems and a source of power quality problems. Some of the important concerns are

1.     Waveform Distortions like Harmonics

2.     Transients

3.     Voltage Fluctuations such as Voltage Sags & Swells

4.     Interruptions e.g. Outages & Blinks

1. Waveform Distortions -Harmonics

• Due to substantial increase of non-linear loads such as the use of power electronics circuits and devices, the ac power system suffers from harmonic problems. In general, we may classify sources of harmonics into three categories i.e.

1.     Domestic loads,

2.     Industrial loads,

3.     Control devices.

• A harmonic is “a sinusoidal component of a periodic wave or quantity having a frequency i.e. an integral multiple of fundamental frequency”. Pure or clean power is referred as those without harmonics. But this only exists in laboratories. The frequencies of the harmonics are different, depending on the fundamental frequency. Due to high harmonic voltage and/or current levels, there are a number of equipments that can have miss operation or failures.
• The main sources of harmonic current are the phase angle controlled rectifiers and inverters.
• Although the applied voltage to a transformer is sinusoidal, the magnetization current related to the flux through the lamination magnetization curve is non-sinusoidal. These harmonics have their maximum effect during the first hours of the day (when the system is lightly loaded and the voltage is higher).

2. Transients

• Transients occur in Distribution System due to factors like Lightning, Switching Operations, and Fault Clearing/Breaker Operations etc. The various causes of transients in Customer System are Lightning, Arcing Devices, Starting & Stopping Motors, Breaker Operations, and Capacitor Switching etc.

3. Voltage Fluctuations such as Voltage Sags & Swells

• In Sags, Voltage falls below 90% of normal but stays above 10% of normal for any amount of time. In Swells, Voltage rises above 110% of normal but below 180% of normal for any amount of time. If it’s long enough, you notice lights dimming or getting brighter. Sags are much more common than swells.

4. Interruptions e.g. Outages and Blinks

• Interruptions may be defined as the interrupts that hampers the normal flow of voltage or power quality. When Voltage falls below 10% of normal circuit voltage for any length of time the power supply is off. The outages can be of microseconds to hours or days. When interruptions occur there is a chance of blinking as well.

Control & improvement of The System:

• In order to overcome the various affecting factors, we need to implement some control and improvement measures. They are discussed as follows:

1. Harmonics

• Several techniques are adopted to minimize harmonic effects like increasing pulse number, passive filters and active filters. By use of these techniques we get higher pulse, trap the harmonics and convert the non-linear ac line current into a sinusoidal wave respectively.
• Power quality analysis is really a matter of concern as it is quite evident how important supply of power is especially in organizations where critical loads need continuous supply of clean power and that too without any disruption.
• Technological advancements are developing in this sector in order to manage the advanced and sophisticated power systems with utmost proficiency.

2. Transients

• We can use power enhancers like Surge Suppressors, Lightning Protection/Arrestors, Power Conditioning, Line Reactors/Chokes etc. Power Synthesizers such as Standby Power Systems, UPS & Motor Generator Set can be utilized. Simplest, least expensive way to condition power by clamping voltage when it exceeds a certain level and sending it away from the equipment it protects.
• Transient voltage surge suppressors (TVSS) can be installed at the terminals of the sensitive electronic loads. Power line filters limit noise and transients to a safe level by slowing down the rate of change of these problems and keeping electronic systems safer than surge protectors can.

3. Voltage Fluctuations such as Voltage Sags & Swells

• Use of Power Enhancers like Reduced Voltage Starters on large offending motors, Voltage Regulators, Constant Voltage Transformers (CVTs), Power Conditioners; as well as Power Synthesizers like UPS, Motor-Generator Sets can minimize voltage fluctuations.
• Voltage Regulators can be utilized to maintain voltage output within a desired limit or tolerance regardless how much input voltage varies. They can also be utilized for protection against swells or noise and limited protection from fast voltage changes depending upon the response time of the regulator. Voltage regulators respond best to slow changes in voltage.
• Constant Voltage Transformers (CVT’s), also known as Ferro resonant transformers are used for sags, swells, longer term over and under-voltages, especially attractive for constant, low-power loads like electronic controllers (PLC’s) where they provide ride-through capability. Variable loads, especially those with high inrush currents, (Drives) present more of a problem for CVT’s.

Importance of Reactive Power for System

Introduction:

• We always in practice to reduce reactive power to improve system efficiency .This are acceptable at some level. If system is purely resistively or capacitance it make cause some problem in Electrical system. Alternating systems supply or consume two kind of power: real power and reactive power.
• Real power accomplishes useful work while reactive power supports the voltage that must be controlled for system reliability. Reactive power has a profound effect on the security of power systems because it affects voltages throughout the system.
• Find important discussion regarding importance about Reactive Power and how it is useful to maintain System voltage healthy

 Importance of Reactive Power:

• Voltage control in an electrical power system is important for proper operation for electrical power equipment to prevent damage such as overheating of generators and motors, to reduce transmission losses and to maintain the ability of the system to withstand and prevent voltage collapse.
• Decreasing reactive power causing voltage to fall while increasing it causing voltage to rise. A voltage collapse may be occurs when the system try to serve much more load than the voltage can support.
• When reactive power supply lower voltage, as voltage drops current must increase to maintain power supplied, causing system to consume more reactive power and the voltage drops further . If the current increase too much, transmission lines go off line, overloading other lines and potentially causing cascading failures.
• If the voltage drops too low, some generators will disconnect automatically to protect themselves. Voltage collapse occurs when an increase in load or less generation or transmission facilities causes dropping voltage, which causes a further reduction in reactive power from capacitor and line charging, and still there further voltage reductions. If voltage reduction continues, these will cause additional elements to trip, leading further reduction in voltage and loss of the load. The result in these entire progressive and uncontrollable declines in voltage is that the system unable to provide the reactive power required supplying the reactive power demands

 Necessary to Control of Voltage and Reactive Power:

• Voltage control and reactive power management are two aspects of a single activity that both supports reliability and facilitates commercial transactions across transmission networks.
• On an alternating current (AC) power system, voltage is controlled by managing production and absorption of reactive power.
• There are three reasons why it is necessary to manage reactive power and control voltage.
• First, both customer and power system equipment are designed to operate within a range of voltages, usually within±5% of the nominal voltage. At low voltages, many types of equipment perform poorly, light bulbs provide less illumination, induction motors can overheat and be damaged, and some electronic equipment will not operate at. High voltages can damage equipment and shorten their lifetimes.
• Second, reactive power consumes transmission and generation resources. To maximize the amount of real power that can be transferred across a congested transmission interface, reactive power flows must be minimized. Similarly, reactive power production can limit a generator’s real power capability.
• Third, moving reactive power on the transmission system incurs real power losses. Both capacity and energy must be supplied to replace these losses.
• Voltage control is complicated by two additional factors.
• First, the transmission system itself is a nonlinear consumer of reactive power, depending on system loading. At very light loading the system generates reactive power that must be absorbed, while at heavy loading the system consumes a large amount of reactive power that must be replaced. The system’s reactive power requirements also depend on the generation and transmission configuration.
• Consequently, system reactive requirements vary in time as load levels and load and generation patterns change. The bulk power system is composed of many pieces of equipment, any one of which can fail at any time. Therefore, the system is designed to withstand the loss of any single piece of equipment and to continue operating without impacting any customers. That is, the system is designed to withstand a single contingency. The loss of a generator or a major transmission line can have the compounding effect of reducing the reactive supply and, at the same time, reconfiguring flows such that the system is consuming additional reactive power.
• At least a portion of the reactive supply must be capable of responding quickly to changing reactive power demands and to maintain acceptable voltages throughout the system. Thus, just as an electrical system requires real power reserves to respond to contingencies, so too it must maintain reactive-power reserves.
• Loads can also be both real and reactive. The reactive portion of the load could be served from the transmission system. Reactive loads incur more voltage drop and reactive losses in the transmission system than do similar size (MVA) real loads.
• System operation has three objectives when managing reactive power and voltages.
• First, it must maintain adequate voltages throughout the transmission and distribution system for both current and contingency conditions.
• Second, it seeks to minimize congestion of real power flows.
• Third, it seeks to minimize real power losses.

 Basic concept of Reactive Power

 1)    Why We Need Reactive Power:

• Active power is the energy supplied to run a motor, heat a home, or illuminate an electric light bulb. Reactive power provides the important function of regulating voltage.
• If voltage on the system is not high enough, active power cannot be supplied.
• Reactive power is used to provide the voltage levels necessary for active power to do useful work.
• Reactive power is essential to move active power through the transmission and distribution system to the customer .Reactive power is required to maintain the voltage to deliver active power (watts) through transmission lines.
• Motor loads and other loads require reactive power to convert the flow of electrons into useful work.
• When there is not enough reactive power, the voltage sags down and it is not possible to push the power demanded by loads through the lines.”

2)    Reactive Power is a Byproduct of AC Systems

• Transformers, Transmission lines, and motors require reactive power. Electric motors need reactive power to produce magnetic fields for their operation.
• Transformers and transmission lines introduce inductance as well as resistance

1. Both oppose the flow of current
2. Must raise the voltage higher to push the power through the inductance of the lines
3. Unless capacitance is introduced to offset inductance

3)    How Voltages Controlled by Reactive Power:

• Voltages are controlled by providing sufficient reactive power control margin to supply needs through

1. Shunt capacitor and reactor compensations
2. Dynamic compensation
3. Proper voltage schedule of generation.

• Voltages are controlled by predicting and correcting reactive power demand from loads

4)    Reactive Power and Power Factor

• Reactive power is present when the voltage and current are not in phase

1. One waveform leads the other
2. Phase angle not equal to 0°
3. Power factor less than unity

• Measured in volt-ampere reactive (VAR)
• Produced when the current waveform leads voltage waveform (Leading power factor)
• Vice verse, consumed when the current waveform lags voltage (lagging power factor)

5)    Reactive Power Limitations:

• Reactive power does not travel very far.
• Usually necessary to produce it close to the location where it is needed
• A supplier/source close to the location of the need is in a much better position to provide reactive power versus one that is located far from the location of the need
• Reactive power supplies are closely tied to the ability to deliver real or active power.

 Reactive Power Caused Absence of Electricity -A Blackout

• The quality of the electrical energy supply can be evaluated basing on a number of parameters. However, the most important will be always the presence of electrical energy and the number and duration of interrupts.
• When consumption of electrical energy is high, the demand on inductive reactive power increases at the same proportion. In this moment, the transmission lines (that are well loaded) introduce an extra inductive reactive power. The local sources of capacitive reactive power become insufficient. It is necessary to deliver more of the reactive power from generators of power plants.
• It might happen that they are already fully loaded and the reactive power will have to be delivered from more distant places. Transmission of reactive power will load more the lines, which in turn will introduce more reactive power. The voltage on customer side will decrease further. Local control of voltage by means of auto transformers will lead to increase of current (to get the same power) and this in turn will increase voltage drops in lines. In one moment this process can go like avalanche reducing voltage to zero. In mean time most of the generators in power plants will switch off due to unacceptably low voltage what of course will deteriorate the situation.
• Insufficient reactive power leading to voltage collapse has been a causal factor in major blackouts in the worldwide. Voltage collapse occurred in United States in the blackout of July 2, 1996, and August10, 1996 on the West Coast
• While August 14, 2003, blackout in the United States and Canada was not due to a voltage collapse as that term has traditionally used by power system engineers, the task force final report said that” Insufficient reactive power was an issue in the blackout” and the report also “overestimation of dynamics reactive output of system generation ” as common factor among major outages in the United States.
• Demand for reactive power was unusually high because of a large volume of long-distance transmissions streaming through Ohio to areas, including Canada, than needed to import power to meet local demand. But the supply of reactive power was low because some plants were out of service and, possibly, because other plants were not producing enough of it.”

 Problem of Reactive Power:

• Though reactive power is needed to run many electrical devices, it can cause harmful effects on appliances and other motorized loads, as well as electrical infrastructure. Since the current flowing through electrical system is higher than that necessary to do the required work, excess power dissipates in the form of heat as the reactive current flows through resistive components like wires, switches and transformers. Keep in mind that whenever energy is expended, you pay. It makes no difference whether the energy is expended in the form of heat or useful work.
• We can determine how much reactive power electrical devices use by measuring their power factor, the ratio between real power and true power. A power factor of 1 (i.e. 100%) ideally means that all electrical power is applied towards real work. Homes typically have overall power factors in the range of 70% to 85%, depending upon which appliances may be running. Newer homes with the latest in energy efficient appliances can have an overall power factor of 90%.
• Electric companies correct for power factor around industrial complexes, or they will request the offending customer to do so, or they will charge for reactive power. Electric companies are not worried about residential service because the impact on their distribution grid is not as severe as in heavily industrialized areas. However, it is true that power factor correction assists the electric company by reducing demand for electricity, thereby allowing them to satisfy service needs elsewhere.
• Power factor correction will not raise your electric bill or do harm to your electrical devices. The technology has been successfully applied throughout industry for years. When sized properly, power factor correction will enhance the electrical efficiency and longevity of inductive loads. Power factor correction can have adverse side effects (e.g. harmonics) on sensitive industrialized equipment if not handled by knowledgeable, experienced professionals. Power factor correction on residential dwellings is limited to the capacity of the electrical panel (200 amp max) and does not over compensate household inductive loads. By increasing the efficiency of electrical systems, energy demand and its environmental impact is lessened

 Effects of Reactive Power in Various elements of Power System:

 1)    Generation:

• An electric power generator’s primary function is to convert fuel into electric power. Almost all generators also have considerable control over their terminal voltage and reactive-power output.
• The ability of   generator to provide reactive support depends on its real power production. Like most electric equipment, generators are limited by their current carrying capability. Near rated voltage, this capability becomes an MVA limit for the armature of the generator rather than a MW limitation.
• Production of reactive power involves increasing the magnetic field to raise the generator’s terminal voltage. Increasing the magnetic field requires increasing the current in the rotating field winding. Absorption of reactive power is limited by the magnetic-flux pattern in the stator, which results in excessive heating of the stator-end iron, the core-end heating limit.
• The synchronizing torque is also reduced when absorbing large amounts of reactive power, which can also limit generator capability to reduce the chance of losing synchronization with the system.
• The generator prime mover (e.g., the steam turbine) is usually designed with less capacity than the electric generator, resulting in the prime-mover limit. The designers recognize that the generator will be producing reactive power and supporting system voltage most of the time. Providing a prime mover capable of delivering all the mechanical power the generator can convert to electricity when it is neither producing nor absorbing reactive power would result in under utilization of the prime mover.
• To produce or absorb additional VARs beyond these limits would require a reduction in the real power output of the unit. Control over the reactive output and the terminal voltage of the generator is provided by adjusting the DC current in the generator’s rotating field .Control can be automatic, continuous, and fast.
• The inherent characteristics of the generator help maintain system voltage. At any given field setting, the generator has a specific terminal voltage it is attempting to hold. If the system voltage declines, the generator will inject reactive power into the power system, tending to raise system voltage. If the system voltage rises, the reactive output of the generator will drop, and ultimately reactive power will flow into the generator, tending to lower system voltage. The voltage regulator will accentuate this behavior by driving the field current in the appropriate direction to obtain the desired system voltage.

 2)    Synchronous Condensers:

• Every synchronous machine (motor or generator) with a controllable field has the reactive power capabilities discussed above.
• Synchronous motors are occasionally used to provide dynamic voltage support to the power system as they provide mechanical power to their load. Some combustion turbines and hydro units are designed to allow the generator to operate without its mechanical power source simply to provide the reactive power capability to the power system when the real power generation is unavailable or not needed. Synchronous machines that are designed exclusively to provide reactive support are called synchronous condensers.
• Synchronous condensers have all of the response speed and controllability advantages of generators without the need to construct the rest of the power plant (e.g., fuel-handling equipment and boilers). Because they are rotating machines with moving parts and auxiliary systems, they may require significantly more maintenance than static alternatives. They also consume real power equal to about 3% of the machine’s reactive-power rating.

 3)    Capacitors & Inductors:

• Capacitors and inductors (which are sometimes called reactors) are passive devices that generate or absorb reactive power. They accomplish this without significant real power losses or operating expense.
• The output of capacitors and inductors is proportional to the square of the voltage. Thus, a capacitor bank (or inductor) rated at 100 MVAR will produce (or absorb) only 90 MVAR when the voltage dips to 0.95 pu but it will produce (or absorb) 110 MVAR when the voltage rises to 1.05 pu. This relationship is helpful when inductors are employed to hold voltages down.
•  The inductor absorbs more when voltages are highest and the device is needed most. The relationship is unfortunate for the more common case where capacitors are employed to support voltages. In the extreme case, voltages fall, and capacitors contribute less, resulting in a further degradation in voltage and even less support from the capacitors; ultimately, voltage collapses and outages occur.
• Inductors are discrete devices designed to absorb a specific amount of reactive power at a specific voltage. They can be switched on or off but offer no variable control.
•  Capacitor banks are composed of individual capacitor cans, typically 200 kVAR or less each. The cans are connected in series and parallel to obtain the desired capacitor bank voltage and capacity rating. Like inductors, capacitor banks are discrete devices but they are often configured with several steps to provide a limited amount of variable control which makes it a disadvantage compared to synchronous motor.

 4)    Static VAR Compensators : (SVCs)

• An SVC combines conventional capacitors and inductors with fast switching capability. Switching takes place in the sub cycle timeframe (i.e. in less than 1/60 of a second), providing a continuous range of control. The range can be designed to span from absorbing to generating reactive power. Consequently, the controls can be designed to provide very fast and effective reactive support and voltage control.
• Because SVCs use capacitors, they suffer from the same degradation in reactive capability as voltage drops. They also do not have the short term overload capability of generators and synchronous condensers. SVC applications usually require harmonic filters to reduce the amount of harmonics injected into the power system.

 5)     Static Synchronous Compensators : (STATCOMs)

• The STATCOM is a solid-state shunt device that generates or absorbs reactive power and is one member of a family of devices known as flexible AC transmission system.
• The STATCOM is similar to the SVC in response speed, control capabilities, and the use of power electronics. Rather than using conventional capacitors and inductors combined with fast switches, however, the STATCOM uses power electronics to synthesize the reactive power output. Consequently, output capability is generally symmetric, providing as much capability for production as absorption.
•  The solid-state nature of the STATCOM means that, similar to the SVC, the controls can be designed to provide very fast and effective voltage control. While not having the short-term overload capability of generators and synchronous condensers, STATCOM capacity does not suffer as seriously as SVCs and capacitors do from degraded voltage.
• STATCOMs are current limited so their MVAR capability responds linearly to voltage as opposed to the voltage squared relationship of SVCs and capacitors. This attribute greatly increases the usefulness of STATCOMs in preventing voltage collapse.

 6)    Distributed Generation:

• Distributing generation resources throughout the power system can have a beneficial effect if the generation has the ability to supply reactive power. Without this ability to control reactive power output, performance of the transmission and distribution system can be degraded.
• Induction generators were an attractive choice for small, grid-connected generation, primarily because they are relatively inexpensive. They do not require synchronizing and have mechanical characteristics that are appealing for some applications (wind, for example). They also absorb reactive power rather than generate it, and are not controllable. If the output from the generator fluctuates (as wind does), the reactive demand of the generator fluctuates as well, compounding voltage-control problems for the transmission system.
• Induction generators can be compensated with static capacitors, but this strategy does not address the fluctuation problem or provide controlled voltage support. Many distributed generation resources are now being coupled to the grid through solid-state power electronics to allow the prime mover’s speed to vary independently of the power-system frequency. For wind, this use of solid-state electronics can improve the energy capture.
• For gas-fired micro turbines, power electronics equipment allows them to operate at very high speeds. Photovoltaic’s generate direct current and require inverters to couple them to the power system. Energy-storage devices (e.g., batteries, flywheels, and superconducting magnetic-energy storage devices) are often distributed as well and require solid-state inverters to interface with the grid. This increased use of a solid-state interface between the devices and the power system has the added benefit of providing full reactive-power control, similar to that of a STATCOM.
• In fact, most devices do not have to be providing active power for the full range of reactive control to be available. The generation prime mover, e.g. turbine, can be out of service while the reactive component is fully functional. This technological development (solid-state power electronics) has turned a potential problem into a benefit, allowing distributed resources to contribute to voltage control.

 7)    Transmission Side:

• Unavoidable consequence of loads operation is presence of reactive power, associated with phase shifting between voltage and current.
• Some portion of this power is compensated on customer side, while the rest is loading the network. The supply contracts do not require a cosφ equal to one. The reactive power is also used by the transmission lines owner for controlling the voltages.
• Reactive component of current adds to the loads current and increases the voltage drops across network impedance. Adjusting the reactive power flow the operator change voltage drops in lines and in this way the voltage at customer connection point.
• The voltage on customer side depends on everything what happens on the way from generator to customer loads. All nodes, connection points of other transmission lines, distribution station and other equipment contribute to reactive power flow.
• A transmission line itself is also a source of reactive power. A line that is open on the other end (without load) is like a capacitor and is a source of capacitive (leading) reactive power. The lengthwise inductances without current are not magnetized and do not introduce any reactive components.  On the other hand, when a line is conducting high current, the contribution of the lengthwise inductances is prevalent and the line itself becomes a source of inductive (lagging) reactive power. For each line can be calculated a characteristic value of power flow.
•  If the transmitted power is more than pre define Value, the line will introduce additionally inductive reactive power, and if it is below pre define Value, the line will introduce capacitive reactive power. The pre define Value depends on the voltage: for 400 kV line is about 32% of the nominal transmission power, for 220 kV line is about 28% and for 110 kV line is about 22%. The percentage will vary accordingly to construction parameters.
• The reactive power introduced by the lines themselves is really a nuisance for the transmission system operator. In the night, when the demand is low it is necessary to connect parallel reactors for consuming the additional capacitive reactive power of the lines. Sometimes it is necessary to switch off a low-loaded line (what definitely affect the system reliability). In peak hours not only the customer loads cause big voltage drops but also the inductive reactive power of the lines adds to the total power flow and causes further voltage drops.
• The voltage and reactive power control has some limitations. A big part of reactive power is generated in power plant unites. The generators can deliver smoothly adjustable leading and lagging reactive power without any fuel costs.
• However, the reactive power occupies the generation capacity and reduces the active power production. Furthermore, it is not worth to transmit reactive power for long distance (because of active power losses). Control provided “on the way” in transmission line, connation nodes, distribution station and other points requires installation of capacitors or\and reactors.
• They are often used with transformer tap changing system. The range of voltage control depends on their size. The control may consist e.g. in setting the transformer voltage higher and then reducing it by reactive currents flow.
•  If the transformer voltage reaches the highest value and all capacitors are in operation, the voltage on customer side cannot be further increase. On the other hand when a reduction is required the limit is set by maximal reactive power of reactors and the lowest tap of transformer.

Assessment Practices to control Voltage & Reactive Power:

• Transmission and Distribution planners must determine in advance the required type and location of reactive correction.

1)    Static vs. Dynamic Voltage Support

• The type of reactive compensation required is based on the time needed for voltage recovery.
• Static Compensation is ideal for second and minute responses. (Capacitors, reactors, tap changes).
• Dynamic Compensation is ideal for instantaneous responses. (condensers, generators)
• A proper balance of static and dynamic voltage support is needed to maintain voltage levels within an acceptable range.

2)    Reactive Reserves during Varying Operating Conditions

• The system capacitors, reactors, and condensers should be operated to supply the normal reactive load. As the load increases or following a contingency, additional capacitors should be switched on or reactors removed to maintain acceptable system voltages.
• The reactive capability of the generators should be largely reserved for contingencies on the EHV system or to support voltages during extreme system operating conditions.
• Load shedding schemes must be implemented if a desired voltage is unattainable threw reactive power reserves

3)    Voltage Coordination

• The reactive sources must be coordinated to ensure that adequate voltages are maintained everywhere on the interconnected system during all possible system conditions. Maintaining acceptable system voltages involves the coordination of sources and sinks which include:

1. Plant voltage schedules
2. Transformer tap settings
3. Reactive device settings
4. Load shedding schemes.

• The consequences of uncoordinated of above operations would include:

1. Increased reactive power losses
2. A reduction in reactive margin available for contingencies and extreme light load conditions
3. Excessive switching of shunt capacitors or reactors
4. Increased probability of voltage collapse conditions.

• Plant Voltage Schedule :Each power plant is requested to maintain a particular voltage on the system bus to which the plant is connected. The assigned schedule will permit the generating unit to typically operate:

1. In the middle of its reactive capability range during normal conditions
2. At the high end of its reactive capability range during contingencies
3. “Under excited” or absorb reactive power under extreme light load conditions.

• Transformer Tap Settings :Transformer taps must be coordinated with each other and with nearby generating station voltage schedules.
• The transformer taps should be selected so that secondary voltages remain below equipment limits during light load conditions.
• Reactive Device Settings :Capacitors on the low voltage networks should be set to switch “on” to maintain voltages during peak and contingency conditions. And “Off” when no longer required supporting voltage levels.
• Load Shedding Schemes: Load shedding schemes must be implemented as a “last resort” to maintain acceptable voltages.

4)    Voltage and Reactive Power Control

• Requires the coordination work of all Transmission and Distribution disciplines.
• Transmission needs to:

1. Forecast the reactive demand and required reserve margin
2. Plan, engineer, and install the required type and location of reactive correction
3. Maintain reactive devices for proper compensation
4. Maintain meters to ensure accurate data
5.  Recommend the proper load shedding scheme if necessary.

• Distribution needs to:

1. Fully compensate distribution loads before Transmission reactive compensation is considered
2. Maintain reactive devices for proper compensation
3. Maintain meters to ensure accurate data
4. Install and test automatic under voltage load shedding schemes

References:

1. Samir Aganoviş,
2.  Zoran Gajiş,
3. Grzegorz Blajszczak- Warsaw, Poland,
4. Gianfranco Chicco
5. Robert P. O’Connell-Williams Power Company
6. Harry L. Terhune-American Transmission Company,
7. Abraham Lomi, Fernando Alvarado, Blagoy Borissov, Laurence D. Kirsch
8. Robert Thomas,
9. OAK RIDGE NATIONAL LABORATORY

 

 

 

Electrical Energy Saving Tips

How to save  Electrical energy at Home

In our home we use lot of electrical equipment like Tv, Freeze, Washing machine,Mp3 player. music system, computer laptop. But we have not adequate knowledge for how to use this electrical equipment in proper way Due to this ignorance we are paying more electricity Bill which we are not actually use.

Do you know in actual we are consuming more electricity or paying more amounts what we actually not use it?

According to the energy auditors we can easily save between 5 and 10% of their energy consumption (and costs) by changing our behavior such as switching electrical equipment off at the mains rather than leaving it on standby, turning off lights when they’re not being used

By saving Electrical energy will directly reflected to saving money so it is very necessary to under stood ghost unit or amount which we are paying without using the appliances.

The major appliances in your home — refrigerators, clothes washers, dishwashers — account for a big chunk of your monthly utility bill. And if your refrigerator or washing machine is more than a decade old, you’re spending a lot more on energy than you need to.

Today’s major appliances don’t hog energy the way older models do because they must meet minimum federal energy efficiency standards. These standards have been tightened over the years, so any new appliance you buy today has to use less energy than the model you’re replacing. For instance, if you buy one of today’s most energy-efficient refrigerators, it will use less than half the energy of a model that’s 12 years old or older.

Lighting

• Get into the habit of turning lights off when you leave a room. —-Saving Energy 0.5 %
• Use task lighting (table and desktop lamps) instead of room lighting.
• Take advantage of daylight
• De-dust lighting fixtures to maintain illumination—–Saving Energy 1 %
• Compact fluorescent bulbs (CFL):

1. CFL use 75% less energy than Normal bulbs.
2. CFL are four times more energy efficient than Normal bulbs.
3. CFL can last up to ten times longer than a normal bulb.

• Use electronic chokes. in place of conventional copper chokes.—-Saving Energy 2 %
• Get into the habit of turning lights off when you leave a room.
• Use only one bulb for light fittings with more than one light bulb, or replace additional bulbs with a lower wattage version.
• Use energy-saving light bulbs that can last up to ten times longer than a normal bulb and use significantly less energy. A single 20- to 25-watt energy-saving bulb provides as much light as a 100-watt ordinary bulb.
• Use tungsten halogen bulbs for spotlights—they last longer and are up to 100% more efficient.
• Fit external lights with a motion sensor.
• Use high frequency fittings for fluorescent tubes because they cut flicker and are even more efficient than energy-saving light bulbs. They are suitable for kitchens, halls, workshops and garages.

Save on Your Fridge & Freezer:

• Defrost your fridge regularly.
• Check that the door seals are strong and intact.
• Don’t stand Freezer’s Back Side too near the Wall.
• Avoid putting warm or hot food in the fridge or freezer—it   requires more energy to cool it down.
• Clean condenser coils twice a year.
• Get rid of old refrigerators!  They use twice the energy as new Energy Star® models.
• Keep refrigerators full but not overcrowded.
• Defrost your fridge regularly. When ice builds up, your freezer uses more electricity. If it frosts up again quickly, check that the door seals are strong and intact.
• Do not stand the fridge next to the oven or other hot appliances if you can help it. Also ensure there is plenty of ventilation space behind and above it.
• Keep the fridge at 40°F and the freezer at 0°F. Empty and then turn your fridge off if you go on a long vacation (but make sure you leave the door open).
• Aim to keep your fridge at least three-quarters full to maintain maximum efficiency. A full fridge is a healthy fridge.
• Avoid putting warm or hot food in the fridge or freezer—it requires more energy to cool it down.

AIR CONDITION UNIT

• For Home Purpose use Window unit Instead Of Split Unit.
• For Office and Commercial Purpose Use Split AC instead of Window unit.
• Consider installing a programmable t. Just set the times and temperatures to match your schedule and you will save money and be comfortably cool when you return home.
• Get air conditioner maintenance each year.
• Checks the condenser coils, the evaporator coils, the blower wheel, the filter, the lubrication and the electrical   contacts.
• Replace worn and dirty equipment for maximum efficiency.
• Replace air conditioner filters every month.
• Turn off central air conditioning 30 minutes before leaving your home.
• Consider using ceiling or portable fans to circulate and cool the air.
• Try increasing your air conditioner temperature. Even 1 degree higher could mean significant savings, and you will probably not notice the difference.
• Keep central air conditioner usage to a minimum—or even turn the unit off—if you plan to go away.
• Consider installing a programmable thermostat. Just set the times and temperatures to match your schedule, and you will save money and be comfortably cool when you return home.
• Get air conditioner maintenance each year—ensure your service person checks the condenser coils, the evaporator coils, the blower wheel, the filter, the lubrication and the electrical contacts. Replace worn and dirty equipment for maximum efficiency.
• Replace air conditioner filters every month.
• Buy the proper size equipment to meet your family’s needs—an oversized air conditioner unit will waste energy.
• If you have a furnace, replace it at the same time as your air conditioner system. Why? Because it is your furnace fan that blows cool air around your home, and a newer furnace fan provides improved air circulation all year round, plus saves energy costs.

Water Heater:

• Check your hot water temperature. It does not need to be any higher than 140°F for washing purposes.
• Plug the basin or bath when you run any hot water.
• Use a timer to make sure the heating and hot water are only on when needed.
• Insulate your hot water pipes to prevent heat loss, and your water will stay hotter for longer. Plus, you will also use less energy to heat it. And simply fitting a jacket onto your hot water tank can cut waste by up to three quarters.
• Take showers—a bath consumes 5 times more hot water. Buy a low-flow showerhead for more efficiency and it will pay for itself in no time.
• Avoid washing dishes under hot running water, and do not pre-rinse before using the dishwasher.
• Repair dripping hot water taps immediately
• Make sure hot water taps are always turned off properly.

Washing Machine:

• Wash full loads of Washing Machine—you will use your machine less often, saving time, and it is more energy-efficient.
• Wash at a lower temperature or the economy setting to save even more.
• Use the spin cycle, and then hang washing out rather than tumble drying—your clothes and linens will smell fresher!
• If you need to tumble dry, try a lower temperature setting.
• Use your dryer for consecutive loads, because the built-up heat between loads will use less energy.

Oven/Electrical Cooker:

• Make sure your oven door closes tightly.
• Use a microwave rather than conventional oven, when possible.
• Keep the center of the pan over the element, and keep the lid on when cooking on the stovetop.
• Only boil the amount of water that you need—just ensure there is enough water to cover the heating element. Turn the element or electric kettle down as soon as it reaches the boiling point.

COMPUTER / LAPTOP

• Buy a laptop instead of a desktop, if practical. —-Saving Energy 5 %.
• If you buy a desktop, get an LCD screen instead of an outdated CRT.
• Use sleep-mode when not in use helps cut  energy costs by approx  40%.
• Turn off the monitor; this device alone uses more than half  the system’s  energy.
• Screen savers save computer screens, not energy.
• Use separate  On/Off switch Socket Instead of One.
• Laser printers use more electricity than inkjet printers.

FAN:

• A ceiling fan in operation through out night will gobble up 22 units in a month.
• There is a wrong notion that fan at more speed would consume more current.
• Fan running at slow speed would waste energy as heat in the regulator.
• The ordinary regulator would take 20 watts extra at low speed.
• The energy loss can be compensated by using  electronic   regulator

Buy efficient electric appliances:

• They use two to 10 times less electricity for the same functionality, and are mostly higher quality products that last longer than the less efficient ones. In short, efficient appliances save you lots of energy and money.
• In many countries, efficiency rating labels are mandatory on most appliances. Look Energy Star label is used.
• The label gives you information on the annual electricity consumption. In the paragraphs below, we provide some indication of the consumption of the most efficient appliances to use as a rough guide when shopping. Lists of brands and models and where to find them are country-specific and so cannot be listed here, but check the links on this page for more detailed information.
• Average consumption of electric appliances in different regions in the world, compared with the high efficient models on the market

Ghost consumers:

• Identify the “ghost consumers” which consume power – not because they are in use, but because they are   plugged in and are in stand-by mode.
• The TV consumes 10 watt power When It’s is in Stand by Mode.

Ex.  TV is in stand-by-mode  for 10 hours a Day.

Energy Consumption  /  Day= 10 X 10 = 100 Watts. = 0.1 KWH.

Energy consumption /  Month= 1X100X30=3000 Watts=3KWH ( Unit) .

Energy Consumption in Rupees. = 3 X 4 = 12 Rs/Month.

• The TV consumes 5 watt power when we  don’t  plug out from switch Board.

Ex.  TV is in un Plug Mode for 10 hours a Day.

Energy Consumption  /  Day= 5 X 10 = 50 Watts. = 0.05 KWH.

Energy consumption /  Month= 1X50X30= 1500 Watts=1.5 KWH ( Unit) .

Energy Consumption in Rupees. = 1.5 X 4 = 6 Rs/Month.

• The cell phone charger uses 3 watt per hour when plugged.
• Mosquito mats consume 5 watts per hour.
• If you use an electric geyser, do not leave it in thermostat mode, for it causes standing losses of 1-1.5 units.