Electrical Engineering Q/A 81-to-90

 81: How energy is generated in Nuclear power plant?

In Nuclear power plant energy is released by nuclear fission. Nuclear fission is the process in which heavy nucleus such as 233U92, 235U92,and 239Pu94 when bombarded by certain particles (protons, neutrons, X-rays), the heavy nucleus will split into two or more smaller nuclei, ejection of two or more neutrons and liberation of vast amount of energy. Therefore this split of heavy nucleus into two or more smaller nuclei is called fission process.

82: What is the Ideal transformer?

Transformer which has characteristics such as no winding resistance, no magnetic leakage, no iron loss or core loss (hysteresis and eddy current loss), and zero magnetising current is termed as Ideal Transformer. Ideal transformer is assumed for better explanation and understanding of practical transformer.

83: What is the difference between high and low tension?

"Tension" is a french word for voltage. Low tension or L.T means low voltage which is upto 1kv and High tension of H T means high voltage which is upto 132kv. We (Residential consumers) are supplied L.T supply, either single phase 220v or three phase 400 where as industrial consumers are supplied H.T.

84: what are tie-lines?

The transmission line which connect one area to another is called Tie-line

85: Why electricity is transmitted at higher voltage and not at lower voltage?

Because Voltage and current are inversely proportional to each other
By sending electricity at higher voltage, we are reducing the current and the main reason of reducing current is because when current flows, it produces heat. More the current flows, more the heat will be produced. Approx 7% Electricity is wasted as heat during transmission. So, to minimize the heat losses, we transfer Electricity at higher voltage.
Another scenerio could be like. Imagine we are transferring at low voltage than current will rise and ultimately we would need a big conductor to accomodate that current flow. Cost of conductor will rise. So, to reduce heat losses and cost of conductor, we transfer at high voltage.

86: What does high starting torque means?

You might have heard that " Machine needs a high starting torque". So what does high starting torque means?
Torque basically is turning effect of force. High starting torque means you need a higher starting force to rotate/move the machine.
Just like when you open the tap of new water bottle, you apply more force to rotate the tap to open it. This is torque.

87: Why we can't store AC in Batteries instead of DC.or Can we store AC in batteries instead of DC?

We cannot store AC in batteries because AC changes their polarity up to 50 (When frequency 50 Hz) or 60 (When frequency = = 60 Hz) times in a second. Therefore the battery terminals keep changing Positive (+ve) becomes Negative (-Ve) and vice versa, but the battery cannot change their terminals with the same speed so that's why we can't store AC in Batteries. in addition, when we connect a battery with AC Supply, then It will charge during positive half cycle and discharge during negative half cycle, because the Positive (+ve) half cycle cancel the negative (-Ve) half cycle, so the average voltage or current in a complete cycle is Zero. So there is no chane to store AC in the Batteries.

88: What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans?

The difference between the electronic and ordinary electrical regulator is that in electronic regulator power losses are less because as we decrease the speed the electronic regulator gives the power needed for that particular speed but in case of ordinary rheostat type regulator, the power wastage is same for every speed and no power is saved. In electronic regulator, triac is employed for speed control by varying the firing angle speed and it is controlled but in rheostatic,control resistance is decreased by steps to achieve speed control.

89: Operation carried out in Thermal power stations?

The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine, the turbine which is coupled with the generator generates the electricity.

90: Why the capacitors works on ac only?

Generally capacitor gives infinite resistance to dc components (i.e., block the dc components). it allows the ac components to pass through.