Question

Mention the type of electricity supplied to our homes and its voltage

Answer 1

First a little bit of History. Initially Power Distribution happened through DC. It was not until 1950's when people started converting to AC. In India, I am one of the few rare ones to have seen and used DC supplies in early 1980 at Howrah, WB. Lets look at what we want as features from the power supply: •Low / Negligible drop over long distances •Non-Lethal •Efficient Power transfer i.e. Low power wastage •Ability to connect Sources and Sinks arbitrarily •Ability to Step-up or Step-down as per requirement with simple equipment Lets see how DC fares: •Very high voltage drop over distances. Needs Power Supply sources at regular intervals to maintain Voltage. •Extremely LETHAL! You might get permanent muscle contraction/expansion injuries as our body works on milli-volts of DC , whereas supplies are typically 100's of volts. •Power wastage is pretty high owing to being associated with the voltage drop. for Example, if a 10MW, 200V DC plant see's a 10% voltage drop the power wasted is also 10% [ 1MW ] based on a simplistic model. In reality it is much greater. •You cannot connect sources arbitrarily. There is always a chance of equipment being damaged due to voltage difference. You have to put in a current limiting resistance which causes associated power loss and voltage drop. •DC-DC converters are typically electronic and did not come along the time when DC supplies were used. So there was NO way to convert voltage levels. And now for AC: •Voltage Drop [ or even rise !! ] is a function of source and load and transmission line impedences. It requires a pretty complex Network Simulation to figure out these drops. Further these drops are not static, they are dynamic that i.e they change every instant. This makes AC capital expensive , as expensive are required to control the plant and distribution centers. •Lethality is a function of Volatge. At 110V, 60Hz [ US ] or 220V,50Hz [ INDIA ] the voltages will cause a tingle but no permanent damage or death. •Power is wasted on the resistive elements of the transmission lines, not due to the capacitive and inductive effects. Thus unless there are faults , power wastage can be controlled greatly.