Articles, Education, Electronics, Electronics Theory, Energy, Home Circuits, Power Supply, Techniques, Technology

How to calculate domestic power consumption? Fact File 24


Electronic Energy Meter (EEM) is used to meter the domestic power consumption for a prescribe period, say one month. The Electronic Energy Meter (EEM) functionally outperforms the traditional Ferrari’s wheel meter. The EEM has many advantages.

1. It reduces the cost of theft and corruption on electricity distribution network with electronic designs and prepayment interfaces.

2. Electronic energy meter measures current in both Phase and Neutral lines and calculate power consumption based on the larger of the two currents.

3. EEM improves the cost and quality of electricity distribution.

Most of the electric appliances consume large amount of current. Heater, Electric iron, Mixi, Grinder, Fridge etc are current hungry appliances. Their uncontrolled use will definitely increase the bill and may change the tariff. If these instruments are kept ON for many hours, your electricity bill will be really shocking. Old humming fan, CRT based TV, Fridge with defroster (its heater switches on frequently to melt the Ice.) etc can also increase the current consumption. Use of these high current devices during the peak hours (when voltage drops) will double the current consumption.

The EEM has a Imp / kWh LED which blinks to indicate Impulses per Kilo Watt Hour. Normally if a 100 watts bulb burns for 1 minute, the pulse rate of LED in the EEM will be 5.3 blinks per minute. + or – 5 times can be considered as normal. If the blinking rate is very high, your EEM is showing a wrong reading and you will be forced to pay more. It is very easy to monitor the power consumption and we can reduce the bill considerably. Remember! unlike mechanical meter, Electronic energy meter will sense very small amount of current. Even a glowing indicator lamp in the switch board will cost something.

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Why careless marking makes mistake in OMR ? Fact File 23


Optical Mark Recognition (OMR) is the technique used to scan a marked paper to detect the presence or absence of the mark in a predetermined position. The OMR reader illuminates a beam of strong light onto the paper for recognizing the marks. The contrasting reflectivity at the predetermined positions is then utilized to detect the marked positions on the paper. The marked areas reflect less light compared to the blank or unmarked areas. If the darkening of bubbles is not perfect or incomplete, the Reader fails to identify the marks and leave the areas as unmarked.

The most important use of OMR is the detection of pencil marked bubbles in optical answer sheets used in Multiple Choice Question (MCQ) examinations. The personal information of the candidate is marked in the data part of the OMR by darkening the appropriate circles. Similarly the answers are also marked by bubbling the suitable circles in the preprinted answer sheet. The OMR reader scans the answer sheet to recover the data and answers. The answer sheets are then graded automatically by the OMR reader. Even if you mark the correct position, if the marking is incomplete, you will not get the score due to error reading.

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Why Currency looks so colourful? Fact File 22



Because it uses Optically Variable Ink or OVI as an Anti counterfeiting measure.OVI is considered as the most complicated type of ink to prevent forgery of documents. The ink has a colourful metal luster with two colours. Various combinations of colours are Red-Green, Gold-Silver, Green-Blue combinations. When viewed under sunlight, the ink gives two colours with optical variation and sharp colour change. Due to its complicated ink production procedure, huge investment, high anti-forgery reliability, it has become an excellent anti-forgery ink. Moreover, the ink is highly resistant to environmental factors such as sunlight, moisture etc.

Depending on the angle of incidence of light, the OVI reflects different wavelengths of white light. As a result, a colour change feels when viewed with unaided eye. If the document is copied using a scanner, only one colour will appear in the image so that it is easy to check the documents with the original one.The OVI is highly useful to show the authenticity of the documents since the use of the ink is strictly controlled and not available easily.

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