Basic Electrical Concepts

• Reactive power  (var) = due to reactive components
• var = volt-ampere reactive ( correct representation is "var" not Var, VAR or VAr)
• Active or real power  (Watt)     = power ratings
• Apparent power (VA)= power consumed

Active Elements

Which have the ability to electrically control the flow of electron. Some active devices allow a voltage to control the flow of electron and some allow another current to control the flow of electron. i.e transistor, SCR's, etc

Passive Elements

Which have not ability of electrical control of  electrons i.e resistor, inductor, etc

• Energy generated / year = max. demand * Load factor * hours in a year

Use of Darlington Pair
It is used to get high current gain.
Practically it is used in many circuits, i.e energy savers.

• In industry one might ask you a question that " how can we get maximum efficiency of a transformer?" The ans is " The efficiency of a transformer will be maximum when the copper loss is equal to the iron loss (Eddy current & Hysterisis).
• Permissible max flux density in a transformer core is 1.6 to 1.8 weber / m.m.

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