A PAPER PRESENTATION ON ADVANCED ENERGY METER BY Mr. Ashish s. Khachane Prof. Ram Meghe Institute of Technology & Reseach ,Badnera “ADVANCED ENERGY METER” ABSTRACT “Science is the study of the world as it is. Engineering is the creation of the world tomorrow” Science is basically “passive” observation of the universe as it exists to generate knowledge. Engineering is making use of that knowledge to meet human needs by creating machine, systems, process and technologies that have not previously existed.
Design and manufacturing are the synthetic part of engineering practice. Manufacturer has received a lot of attention recently for very good economic reasons. Distributed energy should have proper return in form of money to meet of cost of production, transmission and distribution to fix rate for consuming energy, we have to count energy utilized. As well electrical utilities, like any other heavy industries, have greatly increased the familiarity with sophisticated electronics in recent years. Significant changes are taking place in the electric energy industry worldwide.
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Many development came in this field to find how we can measure this energy effectively. First of all came conventional disc type energy meter in this interaction of flux produced by current coil and pressure coil create mechanical counter attached to spindle to which rotating disc is attached. Many times it becomes necessary to find out the energy consumption consumed by our house appliances we use. The project “ADVANCED ENERGY METER” prepared by us can be used to find out how much electricity appliances in our house are using and how much they cost to run. INTRODUCTION
If we want to save power and reduce costs, we need to know how much power each appliance uses over a period of time. Most appliances don’t run all the time, so we need to know the power they use while they are actually running and how much they use over the longer term. The easiest way to determine that is to use an electronic power meter and this new “Energy Meter” fits the bill nicely. It displays the measured power in Watts, the elapsed time and the total energy usage in kWh. In addition, it can show the energy cost in rupees. As a bonus, it also includes comprehensive brownout protection.
One obvious use for this unit it to show refrigerator running costs over a set period of time, so that we can quickly determine the effect of different thermostat settings. Alternatively, it could be used to show the difference in energy consumption between the summer months and the winter months. If we have a solar power installation, this unit will prove invaluable. It will quickly allow us to determine which appliances are the most “power hungry”, so that we can adjust our energy usage patterns to suit the capacity of the installation.
And there are lots of other uses ??? for example, the unit could be used to determine the cost of pumping water, the running costs of an aquarium or even the cost of keeping our TV set on standby power, so that it can be switched on via the remote control. LITERATURE REVIEW Energy Meter:- 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. Problem Definition Standby power The cost of standby power is something that most people never think about.
However, there are lots of appliances in your home that continuously consume power 24 hours a day, even when they are supposedly switched off. These appliances include TV sets, VCRs, DVD players, Hi-fi equipment and cable and satellite TV receivers. They remain on standby so that they are ready to “power up” in response to a command from the remote control. By using the Energy Meter, you can quickly monitor these devices and find out which are the energy wasters. Perhaps when you learn the results, you will be persuaded to turn some of these devices off at the wall or even do away with them altogether!
Brownout protection A bonus feature of the Energy Meter is the inclusion of brownout protection. This means that, when it’s not being used to check energy consumption, the unit can be used to provide brownout protection for a selected appliance. Basically, a brownout occurs when the mains voltage goes low (ie, much lower than the nominal 240VAC) due to a supply fault. This can cause problems because motor-driven appliances (eg, washing machines, air-conditioners, dryers, refrigerators, freezers and pumps) can be damaged by a low mains supply.
If the supply voltage is low, the motor can fail to start (or stall if it’s already running) and that in turn can cause the windings to overheat and burn out. In operation, the Energy meter can switch off power to an appliance during a brownout and restore power when the power is returned to normal. Types of meter 1) Electromechanical induction meter:- 2) Mechanical electricity meter:- 3)Three-phase electromechanical induction meter:- 4) Solid state electricity meter:- BLOCK DIAGRAM Specifications ? Wattage resolution | 0. 01W| Maximum wattage reading | 3750. 00W| ? Kilowatt hour resolution | 1Wh (0. 001kWh)| ? Maximum kWh reading | 99999. 999kWh| ? Cost/kWh resolution | 0. 1 Ru. | ? Maximum cost/kWh reading | 9999. 99| ? Cost/kWh setting from | 0-25. 5 Rs| ? Timer resolution | 0. 1h (6 minutes)| ? Maximum timer value | 9999. 9h| ? Timer accuracy (uncalibrated) typically | ??0. 07%| ? Maximum load current | 10A (15A surge)| ? Reading linearity | 0. 1% over a 1000:1 range| ? Frequency range of measurement | 40Hz to 1kHz| ? Battery current drain during back-up | 10mA| Accuracy | Depends on calibration (error can be ;0. 5%)| ? Accuracy drift with temperature | 0. 002%/??C| ? Brownout voltage detection accuracy after calibration | ??2%| ? Brownout return delay | 18-24 minutes| ? Wattage calibration adjustment | 0. 0244% of reading per step (??2048 steps)| ? Zero Offset adjustment | 0. 12% of reading per step| ? Current monitoring resistance | 1% tolerance, 20ppm/??C coefficient| CIRCUIT DIAGRAM COMPONENT DESCRIPTION IC ADE7756AN The ADE7756 is a high-accuracy electrical power measurement IC with a serial interface and a pulse output.
The ADE7756 incorporates two second-order sigma-delta ADCs, reference circuitry, temperature sensor, and all the signal processing required to perform active power and energy measurement. FEATURES * High Accuracy, Less than 0. 1% Error over a Dynamic Range of 1000 to 1 * An On-Chip User Programmable Threshold for Line Voltage SAG Detection and PSU Supervisory * The ADE7756 Supplies Sampled Waveform Data (20 Bits) and Active Energy (40 Bits) * Digital Power, Phase and Input Offset Calibration, On-Chip Temperature sensor,Compatible Serial Interface * A
Pulse Output with Programmable Frequency * An Interrupt Request Pin (IRQ) and Status Register provide early warning of register Overflow and Other Conditions * Single 5 V Supply, Low Power (25 mW Typical) IC PIC16F628 PIC16F627A/628A/648A microcontrollers typically achieve a 2:1 code compression and a 4:1 speed improvement over other 8-bit microcontrollers in their class. PIC16F627A/628A/648A devices have integrated features to reduce external components, thus reducing system cost, enhancing system reliability and reducing power consumption. Special Microcontroller Features: Internal and external oscillator options: – Precision internal 4 MHz oscillator factory calibrated to ??1% – Low-power internal 48 kHz oscillator – External Oscillator support for crystals and resonators ??? Power-saving Sleep mode,Programmable weak pull-ups on PORTB ??? Multiplexed Master Clear/Input-pin ??? Watchdog Timer with independent oscillator for reliable operation ??? Programmable code protection,Brown-out Reset, Power-on Reset ??? Power-up Timer and Oscillator Start-up Timer ??? Wide operating voltage range (2. 0-5. 5V) ??? Industrial and extended temperature range Regulator 7805
The LM78XX series of three terminal regulators is available with several fixed output voltages making them useful in a wide range of applications One of these is local on card regulation eliminating the distribution problems associated with single point regulation The voltages available allow these regulators to be used in logic systems instrumentation HiFi and other solid state electronic equipment Features * Output current in excess of 1A * Internal thermal overload protection * No external components required * Output transistor safe area protection * Internal short circuit current limit Available in the aluminum TO-3 package Liquid Crystal Display (LCD) 16 x 2 A liquid crystal display (LCD) is an electronically-modulated optical device shaped into a thin, flat panel made up of any number of color or monochrome pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector. It is often utilized in battery-powered electronic devices because it uses very small . In recent years LCD is finding wide spread use replacing 7 segment LEDs or other multisegment LEDs. This is due to following reasons: * The declining process of LCDs. The ability to display numbers, characters, graphics. This is in contrast to LEDs. Which are limited to numbers and a few characters. * In corporation of a refreshing controller into the LCD, thereby relieving the CPU of the task of refreshing LCD. In contrast the LED must be refreshed by the CPU to keep displaying the data. * Ease of programming for characters and graphics. Transformer 09 * Transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors ??? the transformer’s coils or “windings”. Except for air-core ransformers, the conductors are commonly wound around a single iron-rich core, or around separate but magnetically-coupled cores. A varying current in the first or “primary” winding creates a varying magnetic field in the core (or cores) of the transformer. This varying magnetic field induces a varying electromotive force (EMF) or “voltage” in the “secondary” winding. This effect is called mutual induction. WORKING The internal circuitry operates at mains potential. Two 10A mains leads are fitted to the unit ??? one to supply power from the mains and the other to supply power to the appliance.
The unit is easy to use: simply plug it into the mains and plug the appliance into the output socket. An LCD display is visible through the lid of the case and the only exposed parts are four mains-rated switches. These switches are used to set the display modes, reset values and (initially) to set the calibration values. In use, the Energy Meter is simply connected in-line between the mains supply and the appliance to be monitored. The LCD shows two lines of information and this information includes: (1) the elapsed time; (2) the power consumption in watts; (3) brownout indication; and (4) the energy consumption in kWh (kilowatt-hours).
The elapsed time is shown on the top, left-hand section of the display and is simply the time duration over which the energy has been measured. This is shown in 0. 1 hour increments from 0. 1h (ie, 6 minutes) up to 9999. 9h. That latter figure is equal to just over 416 days or 1 year and 51 days, which should be more than enough for any application! After it reaches this maximum elapsed time, the unit automatically begins counting from 0. 0h again. Alternatively, the timer can be reset to 0. 0h at any time by pressing the Clear switch.
The power consumption figure (watts) is displayed to the right of the elapsed time and is updated approximately once every 11 seconds. This has a resolution of 0. 01W, with a maximum practical reading of 3750. 00W (ie, equal to the power drawn by a 15A load with a 250V supply). A 10A load will give a reading of about 2400W, depending on supply voltage. Immediately beneath this figure is the total energy consumption (in kWh) since the measurement started. This has a range from 0. 000kWh to 99999. 999kWh, with a resolution of 1Wh. The maximum value represents over 4. years of energy consumption for an appliance drawing 2500W continuously. This reading can be reset to 0. 000kWh by pressing the Clear switch. In this case, the switch must be held closed for about four seconds before the RESET is indicated on the display. Finally, brownout indication is shown in the lower left-hand section of the display. It displays “SAG” if the mains level drops below the selected voltage for a set time, with the unit also switching off the power to the connected appliance. Alternatively, under normal power conditions (ie, no brownout), the SAG display is blanked and power is supplied to the appliance.
Function switch Pressing the Function switch on the front panel changes the display reading, so that the energy reading is shown in terms of cost instead of kWh. Once again, this reading can be reset 0. 00 by pressing the Clear switch. The maximum reading is 9999. 99 but this is unlikely to ever be reached. Pressing the Function switch again toggles the energy reading to kWh again. Holding down the Function button switches the Energy Meter into its calibration modes. There are eight adjustment modes available here and these can be cycled through by holding the button down or selected in sequence with each press of the Function switch.
We’ll take a closer look at the various calibration modes. Making power measurements In operation, the Energy Meter measures the true power drawn by the load. It is not affected by the shape of the waveform, provided that the harmonics do not extend above 1kHz and the level does not over range. In a DC (direct current) system, the power can be determined by measuring the applied voltage (V) and the current (I) through the load and then multiplying the two values together (ie, P = IV).
Similarly, for AC (alternating current) supplies (eg, 240V mains), the instantaneous power delivered to a load is obtained by multiplying the instantaneous current and voltage values together. However, that’s not the end of the story when it comes to average power consumption, as we shall see. Fig. 1: this graph shows the voltage (V) and current (I) waveforms in phase with each other. Note that the instantaneous power is always positive for this case. Fig. 1 shows a typical situation where the current and voltage waveforms are both sinewaves and are in phase with each other (ie, they both pass through zero at the same time).
In this case, the instantaneous power waveform is always positive and remains above zero. That’s because when we multiply the positive-going voltage and current signals, we get a positive result. Similarly, we also get a positive value when we multiply the negative-going voltage and current signals together. The average (or real) power is represented by the dotted line and can be obtained by filtering the signal to obtain the DC component. In the case of in-phase voltage and current waveforms, it can also be obtained by measuring both the voltage and the current with a meter and multiplying the two values together.
For example, the voltage shown in Fig. 1 is a 240V RMS AC waveform and this has a peak value of 339V. The current shown is 10A RMS with a peak value of 14. 4A. Multiplying the two RMS values together gives 2400W, which is the average power in the load. Note that, in this case, the power value is the same whether we average the instantaneous power signal or multiply the RMS values of the voltage and current. Multimeters are calibrated to measure the RMS value of a sinewave, so if a sinewave has a peak value of 339V, the meter will read the voltage as 240V (ie, 0. 7071 of the peak value).
For non-sinusoidal waveforms, only a “true RMS” meter will give the correct voltage and current readings. RMS is shorthand for “root mean square”, which describes how the value is mathematically calculated. In practice, the RMS value is equivalent to the corresponding DC value. This means, for example, that if we apply 1A RMS to a 1? load, the power dissipation will be 1W ??? exactly the same as if we had applied a 1A DC current to the load. The waveforms in Fig. 1 are typical of a load that is purely resistive, where the current is exactly in phase with the voltage. Such loads include electric light bulbs and electric radiators.
By contrast, capacitive and inductive loads result in out-of-phase voltage and current waveforms. If the load is capacitive, the current will lead the voltage. Alternatively, if the load is inductive, the current will lag the voltage. Inductive loads include motors and fluorescent lamps. The amount that the current leads or lags the voltage is called the power factor ??? it is equal to 1 when the current and voltage are in phase, reducing to 0 by the time the current is 90?? out of phase with the voltage. Calculating the power factor is easy ??? it’s simply the cosine of the phase angle (ie, cosf).
Lagging current Fig. 2 shows the resulting waveforms when the current lags the voltage by 45??. In this case, the resulting instantaneous power curve has a proportion of its total below the zero line. This effectively lowers the average power, since we have to subtract the negative portion of the curve from the positive portion. Fig. 2: Diagram showing what happens when the current lags the voltage by 45??. In this case, the resulting instantaneous power curve has a proportion of its total below the zero line, effectively lowering the average power. And that’s where the problems start.
If we now measure the voltage (240V) and current (10A) using a multimeter and then multiply these values together, we will obtain 2400W just as before when the two waveforms were in phase. Clearly, this figure is no longer correct and the true power is, in fact, much lower, at 1697W. This discrepancy arises because the power factor wasn’t considered. To correct for this, we have to multiply our figure of 2400W by the power factor (ie, cos45?? = 0. 7071). So the true power is 2400 x 0. 7071 = 1697W. These calculations become even more interesting when the current leads or lags the voltage by 90?? as shown in Fig. ??? ie, we have a power factor of 0. In this case, the voltage and current waveforms still measure 240V and 10A respectively when using a multimeter but the power dissipation is now zero. This is because the same amount of instantaneous power is both above and below the zero line. This means that even though there is 10A of current flowing, it does not deliver power to the load. FLOW-CHART Features * Displays power in Watts * Displays energy usage in kWh * Displays measurement period in hours * Displays energy cost * Brownout detection and power switching LCD module shows several readings simultaneously * Calibration for power, offset and phase * Adjustment of Ru. /kWh for cost reading * Adjustment of brownout voltage threshold, calibration, hysteresis & duration. * Optional delayed return of power after brownout is restored to normal voltage CONCLUSION Intelligent energy meter is nothing but meter made up of electronic component which do not contain any mechanical or moving part so that we can reduce mechanical losses which are very common in conventional energy meter, also we have control action in this meter with the help microcontroller.
This intelligent energy meter is microcontroller based. The logic behind the meter is to find out the electricity consumption of our house appliances. This energy meter is constructed with so many features like displaying the power in watts, display energy uses in kWh, displays measurement period in hours, displays energy cost etc. REFERENCES 1) www. myke. com 2) http://www. analog. com/ 3) http://Design???NET. com