What Are Two Types Of Clearance In A Turbine?

1. Radial - clearance at the tips of the rotor and casing.
2. Axial - the fore-and-aft clearance, at the sides of the rotor and the casing.

What Is The Function Of A Thrust Bearing?

Thrust bearings keep the rotor in its correct axial position.

What Is A Balance Piston?

Reaction turbines have axial thrust because pressure on the entering side is greater than pressure on the leaving side of each stage. To counteract this force, steam is admitted to a dummy (balance) piston chamber at the low-pressure end of the rotor. Some designers also use a balance piston on impulse turbines that have a high thrust. Instead of piston, seal strips are also used to duplicate a piston's counter force.

What is Li-Po batteries?

Li-Po batteries:

These are also called as Lithium Ion polymer rechargeable batteries because it uses high conductivity polymer gel/polymers electrolyte instead of liquid electrolyte. These come under the Li-ion technology. These are a bit costly. But the battery is very highly protected when compared to the Li-ion batteries. It has Power density of 185 Wh/Kg.

Advantages:

1. These are highly protective compared to Li-ion batteries.
2. Very light in weight
3. Thin in structure when compared to Li-ion batteries.
4. Power density, nominal voltages are comparatively very high compared to Ni-Cad and Ni-MH batteries.

Disadvantages:

1. Expensive.
2. Might explode if wrongly connected.
3. Should not be bent or exposed to high temperature which may cause to explosion.

Applications: Can be used in all the portable devices which need rechargeable advantage like drones, robotics, RC toys etc.

What is Li-ion batteries?

Li-ion batteries: These are made up of Lithium metal and are latest in rechargeable technology. As these are compact in size they can be used in most of the portable applications which need high power specifications. These are the best rechargeable batteries available. These have a nominal voltage of 3.7V (most commonly we have 3.6V and 7.2V) and have various ranges of power capacity (starting from 100s of mAh to 1000s of mAh). Even the C-rating ranges from 1C to 10C and Power density of Li-ion batteries is 126 Wh/Kg.

Advantages:

1. Very light in weight.
2. High C-rating.
3. Power density is very high.
4. Cell voltage is high.

Disadvantages:

1. These are a bit expensive.
2. If the terminals are short circuited the battery might explode.
3. Battery protection circuit is needed.

What is Ni- MH batteries?

Ni- MH batteries:

The Nickel – Metal Hydride batteries are much preferable than Ni-Cad batteries because of their lower environmental impact. Its nominal voltage is 1.25 V which is greater than Ni-Cad batteries. It has less nominal voltage than alkaline batteries and they are good replacement due to its availability and less environmental impact. The power density of Ni-MH batteries is 100 Wh/Kg.

Advantages:

1. Available in all standard sizes.
2. High power density.
3. Easy to recharge.
4. A good alternative to alkaline which has almost all similarities and also it is rechargeable.

Disadvantages:

1. Self-discharge is very high.
2. Expensive than Ni-Cad batteries.

Applications:

Used in all applications similar to the alkaline and Ni-Cad batteries.

What is Nickel Cadmium Batteries?

Nickel Cadmium Batteries:

These batteries are made of Nickel and Cadmium chemical composition. Though these are very rarely used, these are very cheap and their discharge rate is very low when compared to NiMH batteries. These are available in all standard sizes like AA, AAA, C and rectangular shapes. The nominal voltage is 1.2V, often connected together in a set of 3 which gives 3.6V. It has Power density of 60 Wh/Kg.

Advantages:

1. Cheap in cost
2. Easy to recharge
3. Can be used in all environments
4. Comes in all standard sizes

Disadvantages:

1. Lower power density
2. Contains toxic metal
3. Needs to be charged very frequently in order to avoid growth of crystals on the battery plate.

Applications:

Used in RC toys, cordless phones, solar lights and mostly in the applications where price is important.

What is Lead-acid batteries?

Lead-acid batteries:

It consists of lead-acid which is very cheap and seen mostly in cars and vehicles to power the lighting systems in it. These are more preferable in the products where the size/space and weight doesn’t matter. These comes with the nominal voltage starting 2V to24V and most commonly seen as 2V, 6V, 12V and 24V batteries. It has Power density of 7 Wh/Kg.

Advantages:

1. Cheap in cost
2. Easily rechargeable
3. High power output capability

Disadvantages:

1. Very heavy
2. Occupies much space
3. Power density is very low

Applications:

Used in cars, UPS (uninterrupted Power Supply), robotics, heavy machinery etc..

What is Alkaline battery?

• Alkaline batteries: It is basically constructed with the chemical composition of Zinc (Zn) and Manganese dioxide (MnO₂), as the electrolyte used in it is potassium hydroxide which is purely an alkaline substance the battery is named as alkaline battery having the power density of 100 Wh/Kg.

Advantages:

1. Cycle life is more
2. More compatible and efficient for powering up portable devices.
3. Shelf life is more.
4. Small in size.
5. Highly efficient.
6. Low internal resistance so that discharge state in idle state is less.
7. Leakage is low.

Disadvantages:
Cost is a bit high. Except it everything is an advantage.

Applications:
It can used in torches, remotes, wall clocks, small portable gadgets etc.

What is Coin Cell battery:

Coin cell batteries: The chemical composition of coin cell batteries is also alkaline in nature. Apart from alkaline composition, lithium and silver oxide chemicals will be used to manufacture these batteries which are more efficient in providing steady and stable voltage in such a small sizes. 

It has Power density of 270 Wh/Kg.

Advantages:

1. Light in weight
2. Small in size
3. High density
4. Low cost
5. High nominal voltage (up to 3V)
6. Easy to get high voltages by arranging serially
7. Long shelf life

Disadvantages:

1. Needs a holder
2. Low current draw capability

Applications:

Used in watches, wall clocks, miniature electronic products etc.

Function: strcmp()

C/C++ Programing:

strcmp( leftString[], rightString[] ) 

This function can return three different integer values based on the comparison:

1. Zero

2. An integer greater than zero

3. An integer less than zero.

......................................................................

Code:

int main()

{ 

      

    char leftStr[] = "g f g";

    char rightStr[] = "g f g";

      

    // Using strcmp()

    int res = strcmp(leftStr, rightStr);

      

    if (res==0)

        printf("Strings are equal");

    else 

        printf("Strings are unequal");

      

    printf("\nValue returned by strcmp() is:  %d" , res);

    return 0;

}

.........................................................................

Output: when both string are same it will return zero.

Strings are equal
Value returned by strcmp() is:  0

Source

What is control valve?

• A valve with a pneumatic, hydraulic, electric or other externally powered actuator that automatically opens or closes the valve fully or partially by the signals received from controlling instruments is called control valve.

"A control valve is a valve used to control fluid flow by varying the size of the flow passage as controlled by a signal from a controller."

Parts of Control Valve:

1. Bellows
2. Positioner
3. Stem

Input Signals:

How to check a capacitor?

The capacitor can be checked with a battery operated avometer as below:

• At first a good capacitor shows "dead short" any two terminals  then the resistance reading gradually starts build up as the capacitor begins to charge up to the battery voltage.
• A good capacitor shows almost an infinite resistance between the terminals and the earthing points from the very beginning.

What is battery power density?

Power density:

It defines power capacity of a battery for a given mass of volume.

For example 100 Wh/Kg (Alkaline battery standard power density) implies that for 1 Kg of chemical composition it provides 100 Wh of power capacity.

Now, volume of a AAA alkaline battery is 11.5 grams. So if 1Kg can give 100 Wh capacity, then how much a 11.5 gram AAA battery can give?? 

Let’s calculate.

Wh (for 11.5 gm) = 100*11.5/1000 = 1.15 Wh

 

So, we know the nominal voltage of alkaline battery is 1.5V. So it provides 1.5V * (1.15/1.5)A * 1 hour gives 0.76 Ah = 760 mAh of power capacity which is almost equal to the power capacity of a standard AAA alkaline battery.