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Project Report Final

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SKN - BENTEX GROUP OF COMPANIES COMPANY PROFILE: SKN-BENTEX group started operations 50 years back at Delhi, the capital state of India with manufacturing of Electrical items. Chopra Brothers Mr. Satish Chopra, Mr. Kapil Chopra & Mr. Nishit Chopra have promoted the group. SKN-BENTEX” Group products are at the forefront of innovation in industrial and agricultural field for protection and control of Electric Motor. It is the pioneers and leaders in the field with latest international engineering products based on the world’s best technology since last four decades. “SKN-BENTEX” Group has a rich history of success, which has been achieved through dedication, teamwork and visionary thinking and sincere service of pride in result oriented performance. “SKN- BENTEX” Group has been continuously restructuring to set up state-of-the-art electrical products manufactured at their own plants under strict quality control standard. In this thrust, most of group companies adopted International Quality Standard and have been certified for ISO-9001 Certification and products are also available on ISI-Marked. The SKN-BENTEX Group of Companies engaged in wide range of products and has mainly three subgroups of electrical product range such as “ SKN”, “SKN” Bentex Linger “BENTEX- Linger” with their separate products line and “SKN-BENTEX ” Group is a collection of smaller companies specialist in a
Transcript
Page 1: Project Report Final

SKN - BENTEX GROUP OF COMPANIES

COMPANY PROFILE:

SKN-BENTEX group started operations 50 years back at Delhi, the capital state of India with manufacturing of Electrical items. Chopra Brothers Mr. Satish Chopra, Mr. Kapil Chopra & Mr. Nishit Chopra have promoted the group. SKN-BENTEX” Group products are at the forefront of innovation in industrial and agricultural field for protection and control of Electric Motor. It is the pioneers and leaders in the field with latest international engineering products based on the world’s best technology since last four decades. “SKN-BENTEX” Group has a rich history of success, which has been achieved through dedication, teamwork and visionary thinking and sincere service of pride in result oriented performance. “SKN-BENTEX” Group has been continuously restructuring to set up state-of-the-art electrical products manufactured at their own plants under strict quality control standard. In this thrust, most of group companies adopted International Quality Standard and have been certified for ISO-9001 Certification and products are also available on ISI-Marked. The SKN-BENTEX Group of Companies engaged in wide range of products and has mainly three subgroups of electrical product range such as “ SKN”, “SKN” Bentex Linger “BENTEX-Linger” with their separate products line and “SKN-BENTEX ” Group is a collection of smaller companies specialist in a specific range of products. Besides this “SKN-BENTEX” group engaged in the field of, LPG Home Appliances, LPG Regulators, Building Construction and Export Activities.Home Appliances: LPG Gas Stove , Cooking Range (OTG & Oven), LPG Burner, LPG Regulator & Adaptor, Gas Stove with Copper Brazed Cylinder, Hotel Equipments: Kitchen Equipments, Service Trolleys, Deep & Vertical Freezers, India Railways: Water Tanks, Luggage Racks, Doors.Electrical Appliances: MCB, MCCB, ELCB, Energy Meter, Motor

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Starters & Complete Range of Electrical Products.Mono Block Pump, Exhaust Fan, Auto LPG Conversion Kit with Cylinder, CNG Conversion Kit, Building Construction Township Development, Hotel & Clubs, Retail Shopping Malls, LPG Dispensing Station To undertake Turnkey Project for installation & Commissioning.Haryana City Gas to Undertake Turnkey Project for distribution of Natural Gas to Domestic, Commercial, Industrial and Transport sector.

Firm Type : Nature of Business :Expansion level :

Proprietorship Manufacturer,Export/Import International

Today, with the above wide range of products SKN-Bentex group is a well-recognized name in Indian Household. Group has already achieved turnover of USD 50.00 Millions and has employed more than 1000 employees in eight manufacturing locations in National Capital region of Delhi and regional offices supporting our business through- out the country. After making its presence felt in the domestic market, Group has already spread wings in internationally and started exports to various countries through a separate export division.

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ENERGY METERS

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INTRODUCTION TO ENERGY METERS:An electric meter or energy meter is a device that measures the amount of electrical energy supplied to or produced by a residence, business or machine.Electricity is a clean, convenient way to deliver energy. The electricity meter is how electricity providers measure billable services.The most common type of meter measures kilowatt hours. When used in electricity retailing, the utilities record the values measured by these meters to generate an invoice for the electricity. They may also record other variables including the time when the electricity was used.Since it is expensive to store large amounts of electricity, it must usually be generated as it is needed. More electricity requires more generators, and so providers want consumers to avoid causing peaks in consumption. Electricity meters have therefore been devised that that encourage users to shift their consumption of power away from peak times, such as mid-afternoon, when many buildings turn on air-conditioning.

For these applications, meters measure demand, the maximum use of power in some interval. In some areas, the meters charge more money at certain times of day, to reduce use. Also, in some areas meters have relays to turn off nonessential equipment.Providers are also concerned about efficient use of their distribution network. So, they try to maximize the delivery of billable power. This includes methods to reduce tampering with the meters.Also, the network has to be upgraded with thicker wires, larger transformers, or more generators if parts of it become too hot from excessive currents. The currents can be caused by either real power, in which the waves of voltage and current coincide, or apparent power, in which the waves of current and voltage do not overlap, and so cannot deliver power.Since providers can only collect money for real power, they try to maximize the amount of real power delivered by their networks. Therefore, distribution networks always incorporate electricity meters that measure apparent power, usually by displaying or recording power factors or volt-amp-reactive-hours. Many industrial power meters can measure volt-amp-reactive hours.

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UNITS OF MEASUREMENT:

The most common unit of measurement on the electricity meter is the kilowatt hour, which is equal to the amount of energy used by a load of one kilowatt over a period of one hour, or 3,600,000 joules. Some electricity companies use the SI mega joule instead.Demand is normally measured in watts, but averaged over a period, most often a quarter or half hour.Reactive power is measured in "Volt-amperes reactive", (varh) in kilovar-hours. A "lagging" or inductive load, such as a motor, will have negative reactive power. A "leading", or capacitive load, will have positive reactive power.Volt-amperes measures all power passed through a distribution network, including reactive and actual. This is equal to the product of root-mean-square volts and amperes.

Distortion of the electric current by loads is measured in several ways. Power factor is the ratio of resistive (or real power) to volt-amperes. A capacitive load has a leading power factor, and an inductive load has a lagging power factor. A purely resistive load (such as a filament lamp, heater or kettle) exhibits a power factor of 1. Current harmonics are a measure of distortion of the wave form. For example, electronic loads such as computer power supplies draw their current at the voltage peak to fill their internal storage elements. This can lead to a significant voltage drop near the supply voltage peak which shows as a flattening of the voltage waveform. This flattening causes odd harmonics which are not permissible if they exceed specific limits, as they are not only wasteful, but may interfere with the operation of other equipment. Harmonic emissions are mandated by law in EU and other countries to fall within specified limits.

Other units of measurement: In addition to metering based on the amount of energy used, other types of metering are available.Meters which measured the amount of charge (coulombs) used, known as ampere-hour meters, were used in the early days of electrification. These were dependent upon the supply voltage remaining constant for accurate measurement of energy usage, which was

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not a likely circumstance with most supplies.Some meters measured only the length of time for which current flowed, with no measurement of the magnitude of voltage or current is being made. These were only suited for constant load applications. Neither type is likely to be used today.

TYPES OF METERS:

Modern electricity meters operate by continuously measuring the instantaneous voltage (volts) and current (amperes) and finding the product of these to give instantaneous electrical power (watts) which is then integrated against time to give energy used (joules, kilowatt-hours etc). The meters fall into two basic categories, Electromechanical and Electronic.

ELECTROMECHANICALMETERS

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ELECTRO-MECHANICAL METERS

INTRODUCTION:

The most common type of electricity meter is the Thomson or electromechanical induction watt-hour meter, invented by Elihu Thomson in 1888.The electromechanical induction meter operates by counting the revolutions of an aluminum disc which is made to rotate at a speed proportional to the power. The number of revolutions is thus proportional to the energy usage. It consumes a small amount of power, typically around 2 watts.The metallic disc is acted upon by two coils. One coil is connected in such a way that it produces a magnetic flux in proportion to the voltage and the other produces a magnetic flux in proportion to the current. The field of the voltage coil is delayed by 90 degrees using a lag coil. This produces eddy currents in the disc and the effect is such that a force is exerted on the disc in proportion to the product of the instantaneous current and voltage. A permanent magnet exerts an opposing force proportional to the speed of rotation of the disc. The equilibrium between these two opposing forces results in the disc rotating at a speed proportional to the power being used. The disc drives a register mechanism which integrates the speed of the disc over time by counting revolutions, much like the odometer in a car, in order to render a measurement of the total energy used over a period of time.

The type of meter described above is used on a single-phase AC supply. Different phase configurations use additional voltage and current coils.

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CONSTRUCTION:

The construction varies in details from one manufacturer’s product to the next. However, the differences are very minor in nature.There are four main parts of the operating mechanism:

1. Driving System 3. Braking System2. Moving System 4. Registering System

Driving SystemThe driving system of the meter consists of two electromagnets. The core of the electromagnets is made up of silicon-steel laminations. The core of one of the electromagnets is excited by the load current. This coil is called the current coil. The coil of second electromagnet is connected across the supply and, therefore, carries a current proportional to the supply voltage. This coil is called the pressure coil. Consequently the two electromagnets are known as series and shunt magnets respectively. Copper shading bands are provided on the central limb. The position of these bands is adjustable. The function of these bands is to bring the flux produced by the shunt magnet exactly in quadrature with the applied voltage.

Moving System This consists of an aluminum disc mounted on a light alloy shaft. This disc is positioned in the air gap between series and shunt magnets. The upper bearing of the rotor (moving system) is a steel pin located in a hole in the bearing cap fixed to the top of the shaft. The rotor runs on a hardened steel pivot, screwed to the foot of the shaft. The pivot is supported by a jewel bearing. The pinion engages the shaft with the counting or registering mechanism.

A unique design for the suspension of the disc is used in the floating shaft energy meter. Here the rotating shaft has a small magnet at each end, where the upper magnet of the shaft is attracted to a magnet in the upper bearing and the lower magnet of the shaft is attracted to a magnet in the lower bearing. The moving system thus floats without touching either bearing surface, and the only contact with the movement is that of the gear connecting the shaft with the gear of the train, thus the friction is drastically reduced.

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Braking SystemThe permanent magnet positioned near the edge of the of the Aluminum disc forms the braking system. The aluminum disc moves in the field of this magnet and thus provides a braking torque. The position of the permanent magnet is adjustable, and therefore, braking torque can be adjusted by shifting the permanent magnet to different radial positions.

Registering System The function of a registering or a counting mechanism is to record continuously a number which is proportional to the revolutions made by the moving system. By a suitable system, a train of reduction gears the pinion on the rotor shaft drives a series of five or six pointers. These rotate on round dials which are marked with ten equal divisions.

OPERATIONThe supply voltage is applied across the pressure coil. The pressure coil winding is highly inductive as it has very large number of turns and the reluctance of its magnetic circuit is very small owing to presence of air gaps of very small length. Thus the current I through the pressure coil is proportional to the supply voltage and lags it by a few degrees less than 90. This is because the winding has a small resistance and there are iron losses in the magnetic circuit. Current produces a flux. This flux divides itself into two parts. The major portion of it flows across the side gaps as reluctance of this path is small. The reluctance to the path of flux is large and hence its magnitude is small. This flux goes across aluminum disc and hence is responsible for production of driving torque. Flux is in phase with current I and is proportional to it. Therefore flux is proportional to voltage V and lags it by an angle a few degrees less than 90. Since flux is alternating in nature, it induces an eddy emf E in the disc which in turn produces eddy currents. The load current I flows through the current coil and produces a flux. This flux is proportional to the load current and is in phase with it. This flux produces eddy current Ies in the disc. Now the eddy current Ies interacts with flux to produce a torque and eddy current interacts with flux to produce another torque. These two torques are in opposite direction and the net torque is the difference of these.

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Some Important Readings:

Lag Adjustment Devices:Meter will register true energy only if the angle is made equal to 90. Thus the angle between the shunt magnet flux and the supply voltage V should be equal to 90. This requires that the pressure coil winding should be so designed that it is highly inductive and has a low resistance and the iron losses in the core are small. But even with this the phase of flux is not 90 wrt V but a few degrees less than 90

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The required mmf is obtained from a ‘lag coil’ which is located on the central limb of the shunt magnet close to the disc gap and links with the flux that cuts the disc.The arrangements for adjusting the mmf of the lag coil are:

1. Adjustable Resistance: A few turns of fairly thick wire are placed around the central limb of the shunt magnet and the circuit is closed through a low adjustable resistance. The resistance of this circuit is altered to adjust the lag angles of flux. The resistance of the lag coil is so adjusted that angle becomes equal to 90.

2. Shading Bands: In this, copper shading bands L are placed around the central limb of shunt magnet instead of a lag coil with adjustable resistance. The adjustment can be done by moving the shading bands along the axis of the limb. As the shading bands are moved up the limb, they embrace more flux. This results in greater values for induced emf, current and mmf AT produced by the shading bands and therefore the values of lag angle decreases.

Light Load or Friction Compensation:Despite every care taken in the design of both the jeweled-pivot bearing, which forms the lower bearing for the spindle, and of the simple sleeve pin-type bearing at the top of the spindle, friction errors are liable to be serious particularly at light loads. In order to ensure accurate registration at low loads, it is therefore necessary to arrange for small torque, practically independent of the load on the meter, which acts in the direction of rotation and which is nearly as possible equal in magnitude to the friction torque. This is usually obtained by means of a small shading loop situated between the centre pole of the shunt magnet and the disc and slightly the one side of the centre-line of the pole.

CREEP:In some meters a slow but continuous rotation is obtained even when there is no current flowing through the current coil and only pressure coil is energized. This is called creeping. The major cause for creeping is over-compensation for friction. If the friction compensating device is adjusted to give a driving torque to compensate for starting friction which is bigger than the running friction, there is a tendency for the disc to run even when there is no current through the current coils because the friction compensation torque is independent of the load current as the compensating device is voltage actuated. The other causes for creeping are excessive voltage across the potential coil, vibrations, and stray magnetic fields.

In order to prevent this creeping two diametrically opposite holes are drilled in the disc, the disc will come to rest with one of the holes under the edge of a pole of the shunt magnet, the rotation being thus limited to a maximum of half a revolution.In some cases a small piece of iron is attached to the edge of the disc. The force of attraction exerted by the brake magnet on the iron piece is sufficient to prevent creeping of disc.

Overload CompensationIts customary to add an overload compensating device. This usually takes the form of a magnetic shunt for the series magnet core. The magnetic shunt approaches saturation and so its permeability decreases at overloads. Thus at large currents the magnetic shunt

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diverts less of series magnet flux, so that a larger portion of the flux appears in the disc air gap and contributes to driving torque.

Voltage CompensationA certain amount of variation is permitted in the declared voltage of supply. Therefore, energy meters must be compensated for this variation. Voltage variations cause errors owing to two reasons:

1. The relationship between shunt magnet flux and the supply voltage is not linear owing to saturation in iron parts;

2. The shunt magnet flux produces a dynamically induced emf in the disc which in turn results in a self-braking torque which is proportional to square of the supply voltage.

Temperature CompensationAn increase in temperature is accompanied by a rise in resistance of all copper and alluminium parts and results in:

1 A small decrease in the potential coil flux and a reduction in angle of lag between V and flux.2 A decrease in torques produced by all shading bands3 An increase in the resistance of the eddy current paths4 A decrease in the angle of lag of the eddy currents

ERRORS IN SINGLE PHASE ENERGY METERSThe errors caused by the driving system are:

1. Incorrect magnitude of fluxes: This maybe due to abnormal values of current or voltage. The shunt magnet flux maybe in error due to changes in resistance of coil or due to abnormal frequencies.

2. Incorrect phase angles : There may not be proper relationship between the various phasors. This maybe due to improper lag adjustments, abnormal frequencies. Change in resistance with temperature etc.

3. Lack of Symmetry in magnetic circuit : In case the magnetic circuit is not symmetrical, a driving toque is produced which makes the meter creep.

The errors caused by the Braking system are:1. Changes in strength of brake magnet2. Changes in disc resistance3. Self braking effect of series magnet flux4. Abnormal friction of moving parts

ADJUSTMENT IN SINGLE PHASE ENERGY METERS

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Some adjustments are carried out in energy meters so that they read correctly and their errors are within allowable limits. The sequences of these adjustments are:

1. Preliminary Light Load Adjustment: The disc is so positioned that the holes are not underneath the electromagnets. Rated voltage is applied to the potential coil with no current through the current coil. The light load device is adjusted until the disc just fails to start.

2. Full Load Unit Factor Adjustment: The pressure coil is connected across the rated supply voltage and rated full load current at unity power factor is passed through the current coils.

3. Lag Adjustment (Low Power factor adjustment): The pressure coil is connected across rated supply voltage and rated full load current is passed through the current coil at 0.5 p.f. lagging. The lag device is adjusted till the meter runs at correct speed.

4. The performance is rechecked at 0.5 p.f. lagging.5. Creep Adjustment

READING ELECTROMECHANICAL METERS

The aluminum disc is supported by a spindle which has a worm gear which drives the register. The register is a series of dials which record the amount of energy used. The dials may be of the cyclometer type, an odometer-like display that is easy to read where for each dial a single digit is shown through a window in the face of the meter, or of the pointer type where a pointer indicates each digit. It should be noted that with the dial pointer type, adjacent pointers generally rotate in opposite directions due to the gearing mechanism.

The amount of energy represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution. The value 7.2 is commonly seen. Using the value of Kh, one can determine their power consumption at any given time by timing the disc with a stopwatch. If the time in seconds taken by the disc to complete one revolution is t, then the power in watts is

P = 3600. KhT

For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one.

Most domestic electricity meters must be read manually, whether by a representative of the power company or by the customer. Where the customer reads the meter, the reading may be supplied to the power company by telephone, post or over the internet. The electricity company will normally require a visit by a company representative at least annually in order to verify customer-supplied readings and to make a basic safety check of the meter.

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ELECTRONIC METERS

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INTRODUCTION

Electronic meters compared to traditional mechanical solutions in use offer several additional advantages to the utility market. The metering utilities that can be replaced are gas, water and electricity. The advantages are:

• Better reliability • Better accuracy• Ease of calibration• Anti-tampering protection• Automated meter reading• Security• Advanced billing

Of particular importance to the utility company is the tampering of meters. It is estimated that millions of dollars are lost due to the tampering of these meters. Among the tampering are temporary meter disconnect for a period of time before the readings are taken, the use of permanent magnets to saturate current transformers and insertion of mechanical devices to slow down the mechanical turning of the disc.

Electronic energy meters are replacing traditional electromechanical meters in many residential, commercial and industrial applications because of the versatility and low-cost afforded by electronic meter designs. Single- and multi-chip meter designs are helping meter manufacturers and their customers realize these benefits. Thanks to these continually evolving metering ICs, meter builders can implement many features that were impractical with the older mechanical designs.For example, an electronic design can protect against meter tampering and theft of service. It also can measure and record energy usage at different times of the day, so utilities can bill customers for energy based on time of usage. An electronic energy meter also can enable automatic meter reading (AMR), whereby energy metering data is transmitted to the utility over an RF, power line or even infrared communications link. Furthermore, electronic meters pave the way for “sub metering” of smaller operating units (for example, metering each apartment rather than just the building).Improved accuracy and lower power consumption are other benefits of electronic metering. With a mechanical meter, the error in the basic energy usage measurement is on the order of 1%. But with an electronic implementation, it is possible to reduce that error to less than 0.1%. Moreover, running the mechanical meter with its continuously spinning dial may require hundreds of milliamps. That power consumption can be reduced to a couple milliamps in an electronic energy meter, producing big power

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savings for the utility. Electronic meter designs also change the economics of manufacturing energy meters. A single hardware design may be customized for different customers and markets through changes in software. In addition, calibrating the finished meter at the factory is much easier with an electronic meter design. Another consideration is the demand for mechanical-meter replacements that are as inexpensive as possible. In parts of the developing world where many new customers are being connected to the grid, the low cost of the electronic meter is its main attraction.

IC Development:

Since the late 1990s, semiconductor vendors with mixed-signal and data conversion expertise have been developing ICs for electronic energy metering applications.In varying degrees, these components have integrated the energy measurement, calculation and communication functions required to build electronic energy meters ranging from simple function, mechanical-meter replacements to advanced function all solid-state designs.

As in most areas of silicon development, the level of integration for these components grows with time, so that newer ICs offer more functionality and/or less cost. Consequently, the cost of electronic metering is coming down, which, in turn, is affecting the types of meters that are being built. As the metering ICs evolve, there is also a trend to higher accuracy, which is reflected in the energy measurement linearity of the new ICs.The energy metering market is far from monolithic, so metering ICs target different applications. One way to differentiate these chips is by the number of phases that must be measured. Some ICs target single-phase applications, while others are crafted for multiphase (or poly-phase) applications. Within these categories, the chips also are

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distinguished according to whether they target residential, commercial or industrial applications. Another way to segment the energy metering ICs is according to the desired level of meter functionality.

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CONSTRUCTION:

As in the block diagram, the meter has a power supply, a metering engine, A processing and communication engine (i.e. a microcontroller), and other add-on modules such as RTC, LCD display, communication ports/modules and so on.

The metering engine is given the voltage and current inputs and has a voltage reference, samplers and quantisers followed by an ADC section to yield the digitised equivalents of all the inputs. These inputs are then processed using a Digital Signal Processor to calculate the various metering parameters such as powers, energies etc.

The largest source of long-term errors in the meter is drift in the preamp, followed by the precision of the voltage reference. Both of these vary with temperature as well, and vary wildly because most meters are outdoors. Characterizing and compensating for these is a major part of meter design.

The processing and communication section has the responsibility of calculating the various derived quantities from the digital values generated by the metering engine. This also has the responsibility of communication using various protocols and interface with other addon modules connected as slaves to it.

RTC and other add-on modules are attached as slaves to the processing and communication section for various input/output functions. On a modern meter most if not all of this will be implemented inside the microprocessor, such as the Real Time Clock (RTC), LCD controller, temperature sensor, memory and analog to digital converters.

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WORKING:

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Kilowatt-hour meter for determining, from voltage and current signals, the total energy passing through an alternating electrical supply circuit comprises a clock signal generator for generating timing signals at a frequency which is a multiple of the alternating supply frequency, the timing signals being synchronized in phase with the incoming supply frequency, pulse sampling means controlled by said clock signal generator and arranged to sample simultaneously the magnitude of the voltage on and the current in said supply circuit at a predetermined time instant or instants in each cycle and digital data processing means arranged to process the sampled data to determine energy consumption during successive predetermined periods of time and to integrate the successive determinations of energy consumption.

Such an arrangement may be used with a three phase supply in which case the three phase voltages and phase currents are separately sampled or it may be used with a single phase supply in which case only a single voltage and current has to be sampled. The digital data processing means, which is typically a microprocessor system, effects the required computations from the sampled values.

If a single phase supply is considered with the circuit carrying a current I at a voltage V and with a phase lag (or phase lead) between the current and voltage of φ, then if the waveforms were sinusoidal, the power consumption is VI cos φ. Conveniently, this can be measured by pulse sampling during the peak of one of the waveforms. Preferably the measurement is made at the peak of the voltage waveform, so as to determine the instantaneous peak value of V and of I cos φ. The r.m.s. product can be readily determined by processing of this information. It may be preferred to average successive determinations of V and of I cos φ separately over a number of cycles of the alternating supply frequency, typically a few hundred cycles, before determining the product and hence the energy consumption during this period.

The output from the clock signal generator may be integrated, e.g. counted in a digital counter to provide clock time. If a data link is provided, the aforementioned clock signal generator may be utilized to provide clock timing for time-controlled operations, e.g. for example, the customer's data processing means may compute monetary charges; to ensure correct clock time, the integrated output from the clock signal generator may be periodically updated over the data link. It will be understood that such periodic updating is required to correct the clock in the event of any interruption of the supply. Such a clock may be used, for example, for effecting changes in the data processing related to absolute time; e.g. variation of charging rates in accordance with time.

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TESTING OF

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ENERGY METERS

The various tests performed on Energy meters are:

a) TEST OF INSULATION PROPERTIES

b)TEST OF ACCURACY REQUIREMENTS

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c) TEST OF ELECTRICAL REQUIREMENTS

d)TEST FOR ELCTROMAGNETIC COMPATABILITY

e) TEST FOR CLIMATIC INFLUENCES

f) TEST FOR MECHANICAL REQUIREMENTS

A) TEST OF INSULATION PROPERTIES

1. Impulse Voltage Test2. AC Voltage Test3. Insulation Test

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B) TEST OF ACCURACY REQUIREMENTS

1. Test on Limits of Error2. Interpretation of Test Results3. Test of Meter Constant4. Test of Starting Condition5. Test of No Load6. Test of Ambient Temperature

Influence7. Test of Repeatability of Error8. Test of Influence Quantities

c)TEST OF ELECTRICAL REQUIREMENTS

1. TEST OF POWER CONSUMPTION 2. Test of Influence of Supply Voltage3. Test of Influence of Supply Heating4. Test of Influence of Heating5. Test of Influence of Immunity to Earth

Fault

D) TEST FOR ELECTROMAGNETIC COMPATIBILTY

1. RADIO INTERFERENCE MEASUREMENTS

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2. FAST TRANSIENT BURST TEST3. TEST OF IMMUNITY TO ELECTROSTATIC

DISCHARGES4. Test of Immunity to Electromagnetic HF Field

E) TEST FOR CLIMATIC INFLUENCES

i. Dry heat Testii. Cold Test

iii. Damp Heat Cyclic Test

F) TEST FOR MECHANICAL REQUIREMENTS

i. Vibration Testii. Shock Test

iii. Spring Hammer Testiv. Protection against Penetration of dust

and water

MINIATURE CIRCUIT

BREAKERS

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MINIATURE CIRCUIT BREAKER

MCB

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A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.

HISTORY:An early form of circuit breaker was described by Edison in an 1879 patent application, although his commercial power distribution system used fuses. Its purpose was to protect lighting circuit wiring from accidental short-circuits and overloads.

OPERATION:All circuit breakers have common features in their operation, although details vary substantially depending on the voltage class, current rating and type of the circuit breaker.The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the

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trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.Once a fault is detected, contacts within the circuit breaker must open to interrupt the

circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself. Small circuit breakers may be manually operated; larger units have solenoids to trip the mechanism, and electric motors to restore energy to the springs.The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting the circuit. Contacts are made of copper or copper alloys, silver alloys, and other materials. Service life of the contacts is limited by the erosion due to interrupting the arc. Mechanical circuit breakers are usually discarded when the contacts are worn, but power circuit breakers and high-voltage circuit breakers have replaceable contacts.When a current is interrupted, an arc is generated. This arc must be contained, cooled, and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating gas, or oil as the medium in which the arc forms. Different techniques are used to extinguish the arc including:

Lengthening of the arc Intensive cooling (in jet chambers) Division into partial arcs Zero point quenching Connecting capacitors in parallel with contacts in DC circuits

Finally, once the fault condition has been cleared, the contacts must again be closed to restore power to the interrupted circuit.

Short Circuit Current:

A circuit breaker must incorporate various features to divide and extinguish the arc.The maximum short-circuit current that a breaker can interrupt is determined by testing. Application of a breaker in a circuit with a prospective short-circuit current higher than the breaker's interrupting capacity rating may result in failure of the breaker to safely interrupt a fault. In a worst-case scenario the breaker may successfully interrupt the fault, only to explode when reset.

MCB, such as low contact resistance reduces voltage drop and reduction in power loss. It helps to low heat generation: quick arc removal and thereby long life.

MOUNTING ARRANGEMENT:

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MCB's can be installed on Standard (35 mm) DIN Bars by a simple snap action. The MCB mounting is easy tube snapped on and can be removed easily from DIN Bar.

MECHANICAL INTERLOCKING OF MULTIPLE MCB's :

The tripping mechanism of all multiple MCB's is connected internally. This ensures simultaneous tripping of all poles even if the fault occurs in any one of the phases, thus preventing single phase.

Technical Features :

To suit typical circuit and market requirements MCB's are manufactured in two different categories.

B Type (L Series) : This series is specially suitable for protection of equipment like Ovens, GLS lamps , Geysers and general electrical lighting systems. The magnetic tripping of B types MCB starts, above 4 times of the rated current.

C Type (G Series): are designed to protect circuits with inductive loads like motor and generator etc the magnetic tripping commences above 5 times the rated current

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MOTOR STARTORS

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STAR-DELTA MOTOR STARTER

An induction motor's windings can be connected to a 3-phase AC line in two different ways:

wye (star in Europe), where the windings are connected from phases of the supply to the neutral;

Delta (sometimes mesh in Europe), where the windings are connected between phases of the supply.

A delta connection results in a higher voltage to the windings than a wye connection (the voltage is multiplied by). A star-delta starter initially connects the motor in wye, which produces a lower starting current than delta, then switches to delta when the motor has reached a set speed. Disadvantages of this method over DOL starting are:

Lower starting torque, which may be a serious issue with pumps or any devices with significant breakaway torque

Increased complexity, as more contactors and some sort of speed switch or timers are needed

Two shocks to the motor (one for the initial start and another when the motor switches from wye to delta)

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OIL IMMERSED FULLY AUTOMATIC (COMPACT MODEL) STAR-DELTA MOTOR STARTER:

[3 TO 50 HP]

TYPE: SFA C / SFAC[P] / SSAC

440 Volts 3 PhaseRelay Range H.P.

4 - 6.5A 56 – 10A 7.56 – 10A 109 – 14A 1513 - 21A 2020 - 32A 2520 - 32A 3020 - 32A 3530 - 42A 40, 45, 50

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OIL IMMERSED SEMI AUTOMATIC STAR DELTA MOTOR STARTER:

[RATING: 3 HP TO 40 HP]

TYPE: SSA

TECHNICAL SPECIFICATIONTYPE RELAY RANGE H.P.SSA 4 - 6.5A 5.0SSA 6 - 10A 7.5SSA 6 - 10A 10.0SSA 9 - 14A 15.0SSA 13 - 21A 20.0SSA 20 - 32A 25.0SSA 20 - 32A 30.0SSA 20 - 32A 35.0SSA 30 - 42A 40.0

FULLY AUTOMATIC STAR DELTA OIL IMMERSED MOTOR STARTER: 

[3 HP TO 25 HP]

TYPE: BDX SA/FA

TECHNICAL SPECIFICATIONTYPE H.P./KW RELAY RANGE

BDX SA/FA 3.0/2.2 1.8 - 3.0ABDX SA/FA 5.0/3.7 3.6 - 6.0ABDX SA/FA 7.5/5.5 6.0 - 10A

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BDX SA/FA 10.0/7.5 6.0 - 10ABDX SA/FA 15.0/11 9.0 - 15ABDX SA/FA 20.0/15 12.0 - 20ABDX SA/FA 25.0/18.6 15.0 - 25A

OIL IMMERSED MANUAL STAR DELTA MOTOR STARTER:

  [10 TO 200 HP]

TYPE: SSD / SSD (DX) / SSD (SDX)

TECHNICAL SPECIFICATION

  A B C D E Qty. of oil req. in

For Starters(upto 40 H.P.) 400 310 285 290 205 6.5 Ltrs.For Starters (41 to 150 H.P.) 505 415 380 310 210 11.0 Ltrs.

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CEILING FANS

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CEILING FANS

A ceiling fan is a device suspended from the ceiling of a room, which employs hub-mounted rotating paddles to circulate air in order to move air.

HISTORY:

The first ceiling fans appeared in the 1860s and 1870s, in the United States. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. The electrically-powered ceiling fan was invented in 1882 by Philip Diehl. By World War I, most ceiling fans were being manufactured with four blades instead of the original two. Besides making fans quieter, this change allowed them

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to circulate more air, thereby making more efficient use of their motors.

USES:Most ceiling fans can be used in two different ways - for heating or cooling. Most fans have a mechanism, commonly an electrical switch, for reversing the direction in which the blades rotate. In summer, when the fan's direction of rotation is set so that air is blown downward, the breeze created by a ceiling fan speeds the evaporation of sweat on human skin, which is experienced as a cooling effect. In winter, buildings in colder climates are usually heated. Air naturally stratifies — that is, warmer air rises to the ceiling while cooler air sinks to the floor.

PARTS OF A CEILING FAN: An electric motor One to six paddles (called "blades"); usually made of wood, MDF, metal, or

plastic; which mount under, on top of, or on the side of the motor. Metal arms, called blade irons, which connect the blades to the motor. Flywheel, a metal or tough rubber double-torus which is attached to the motor

shaft, and to which the blade irons may be attached. The flywheel inner ring is locked to the shaft by a lock-screw, and the blade irons to the outer ring by bolts that feed into tapped metal inserts. Older flywheels may become brittle and break, a common cause of fan failure. Replacing the flywheel requires disconnecting wiring and removing the switch housing to gain access to the shaft lock-screw.

Rotor, alternative to blade irons

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OPERATION OF A CEILING FAN:

The way in which a fan is operated depends on its manufacturer, style, and the era in which it was made. Operating methods include:

1. Pull-cord control: This is the most common method of operation for household fans. This style of fan is equipped with a metal-bead chain or cloth cord which, when pulled, cycles the fan through the operational speed(s) and then back to off. These fans typically have three speeds (high, medium, and low);

2. Variable-speed control: During the 1970s and 1980s, fans were often produced with a variable-speed control. This was a dial mounted on the fan which, when turned in either direction, continuously varied the speed at which the blades rotated—similar to a dimmer switch for a light fixture.

3. Wall-mounted control: Some fans have their control(s) mounted the wall instead of on the fans themselves; such controls and are usually proprietary and/or specialized switches.

Wireless remote control: In recent years, remote controls have become an affordable option for controlling ceiling fans. While some models do employ this as their sole form of operation, it is more common for a person to purchase an after-market kit and install it on an existing fan. The hand-held remote transmits radio frequency or infrared signals to a receiver unit installed in the fan, which interprets and acts on the signals.

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MONOBLOCK PUMPS

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MONOBLOCK PUMPS

A pump is a device used to move fluids, such as gases, liquids or slurries. A pump displaces a volume by physical or mechanical action. One common misconception about pumps is the thought that they create pressure. Pumps alone do not create pressure; they only displace fluid, causing a flow. Adding resistance to flow causes pressure. Pumps fall into five major groups: direct lift, displacement, velocity, buoyancy and gravity pumps. Their names describe the method for moving a fluid.

APPLICATIONS:Pumps are used throughout society for a variety of purposes. Early applications includes the use of the windmill or watermill to pump water. Today, the pump is used for irrigation, water supply, gasoline supply, air conditioning systems, refrigeration (usually called a compressor), chemical movement, sewage movement, flood control, marine services, etc.

Because of the wide variety of applications, pumps have a plethora of shapes and sizes: from very large to very small, from handling gas to handling liquid, from high pressure to low pressure, and from high volume to low volume.

Liquid and slurry pumps can lose prime and this will require the pump to be primed by adding liquid to the pump and inlet pipes to get the pump started. Loss of "prime" is usually due to ingestion of air into the pump. The clearances and displacement ratios in pumps used for liquids and other more viscus fluids cannot displace the air due to its lower density.

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Pumping Power:The power added to the fluid flow by the pump (Po), is defined using SI units by:

Po = ρ. g. H. QWhere:Po is the output power of the pump (W) ρ is the fluid density (kg/m3) g is the gravitational constant (9.81 m/s2) H is the energy Head added to the flow (m) Q is the flow rate (m3/s) Power is more commonly expressed as kW (103 W) or horsepower (multiply kW by 0.746), H is equivalent to the pressure head added by the pump when the suction and discharge pipes are of the same diameter. The power required to drive the pump is determined by dividing the output power by the pump efficiency. Power needed to pump a given flow against a given head and pipe size, can be calculated using this spread sheet.Various aspects of pumping energy usage are covered in "Energy Efficiency in Pumping". Energy is consumed by the pump, and also lost in the pipework.

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Pump Efficiency:Pump efficiency is defined as the ratio of the power imparted on the fluid by the pump in relation to the power supplied to drive the pump. Its value is not fixed for a given pump, efficiency is a function of the discharge and therefore also operating head. For centrifugal pumps, the efficiency tends to increase with flow rate up to a point midway through the operating range (peak efficiency) and then declines as flow rates rise further. Pump performance data such as this is usually supplied by the manufacturer before pump selection. Pump efficiencies tend to decline over time due to wear (e.g. increasing tolerances and impellers reducing in size).

One important part of system design involves matching the pipeline head loss-flow characteristic with the appropriate pump or pumps which will operate at or close to the point of maximum efficiency. There are free tools that help calculate head needed and show pump curves including their Best Efficiency Points (BEP).[14]

Pump efficiency is an important aspect and pumps should be regularly tested. Thermodynamic pump testing is one method.

SUMMARY

During this complete visit, I got well versed with various electrical devices and circuits. Besides this, I did a deep study about the various methods of theft of electricity and also the techniques used to control such theft, the various latest trends in technology used for energy meters to get an accurate energy measurement.

Once the Energy meters were deeply studied, I gained knowledge about various other products manufactured by the company like MCB’s, Monoblock Pumps, Ceiling Fans and Motor Starters etc.

All in this entire visit has been really beneficial for me in gaining vital practical knowledge about various devices and circuits in the field of Electrical and Electronics.

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