D. Mohan Kumar

One of the major problems that is to be solved in an electronic circuit design is the production of low voltage DC power supply from AC to power the circuit.  The conventional method is the use of a step-down transformer to reduce the 230 V AC to a desired level of low voltage AC. The most suitable and low cost method is the use of aVoltage Dropping Capacitor in series with the phase line.

Selection of the Dropping capacitor and the circuit design requires some technical knowledge and practical experience to get the desired voltage and current. An ordinary capacitor will not do the job since the device will be destroyed by the rushing current from the mains. Mains spikes will create holes in the dielectric and the capacitor will fail to work. X-rated Capacitor specified for the use in AC mains is required for reducing AC voltage. 

The conventional mechanical energy meter is based on the phenomenon of “Magnetic Induction”. It has a rotating aluminium Wheel called Ferriwheel and  many toothed wheels. Based on the flow of current, the Ferriwheel rotates which makes rotation of other wheels. This will be converted into corresponding measurements in the display section. Since many mechanical parts are involved, mechanical defects and breakdown are common. More over chances of manipulation and current theft will be higher.

Electronic Energy Meter is based on Digital Micro Technology (DMT) and uses no moving parts. So the EEM is known as “Static Energy Meter” In EEM the accurate functioning is controlled by a specially designed IC called ASIC (Application Specified Integrated Circuit). ASIC is constructed only for specific applications using Embedded System Technology. Similar ASIC are now used in Washing Machines, Air Conditioners, Automobiles, Digital Camera etc.