Month: May 2023

Why Power Plant capacity rated in MW and not in MVA

Interview Questions / By

Ravi answered

A Power Plant capacity is rated in MW and not in MVA due to following reasons:-

In a power generating station Prime mover i.e. Turbine generates only active power in Watts, Prime mover then rotate generator coupled to this which then converts mechanical power into electrical energy which is further transmitted to transmission lines and then electrical energy being used at homes shops etc. So that we express power plant capacity rating in MW and not in MVA. Which means no matter how large your generator is, but it depends on capacity of Prime mover or turbine i.e. a 50 MW turbine connected to a 90 MVA generator in a power plant will generate only 50 MW power at full load.

Or you can say a power plant rating is expressed in terms of Prime mover/ turbine and not by alternator set coupled to the turbine.

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Robert answered

MVA is the apparent Power i.e. simple product of voltage and current and the power which is supplied and transmitted from generator to load.

MW are the “Real Power” that perform advantageous work, it is always lower than apparent power by an amount called Power factor, power factor less than 1 are caused by load impedences that are not pure resistance.

What LED bulb is equivalent to 100 watt Incandescent bulb?

Uncategorized / By

Ravi answered

Efficiency of bulbs are usually measured in lumen per watt.

So for incandescent bulb efficiency is 15 lumens per watt, it means a 100 watt incandescent bulb efficiency is 1500 lumens.

LED bulb efficiency is 100 lumens per watt now to get 1500 lumens we need 15 watt led bulb. Therefore 15 watt LED is equivalent to 100 watt incandescent bulb.

Pari answered

Incandescent bulb gives 12 lumens/watt.

Fluorescent tubes (commonly known as bar lights) gives 40 lumen/ watt, LED (light emitting diode) gives 129 lumens/ watt theoretically now since we have to achieve 100 lumens/watt, so approximately 12 Volt led can give lumen output equivalent to 100 watt bulb.

Why is Transformer rated in KVA and not in KW ?

Interview Questions / By

Transformer is a device that transfer electrical power from one circuit to another circuit without changing input power and frequency. Or one can say it can step up and step down the voltage while power and frequency remain constant.

Also there are two types of losses in transformer :-

  1. Copper losses

2. Iron losses or Core losses

In transformer Copper loss depend on current flowing through the winding of transformer, while Iron loss depend on Voltage which means total loss of transformer depends on voltage and current which is expressed in VoltAmpere VA and not on load Power factor (P.F.). So Transformer rating is expressed in VA or KVA and not in W or KW.

How to buy Right Air Conditioner in 2023?

Electrical Machines, Uncategorized / By

The summer of 2023 is here and getting hot day by day, Air cooler is good to lower down the room temperature but it can’t remove moisture content from air as it can’t dehumidify the air as a result the room environment is clammy so Air conditioner is best suited for summer.Now the question arises which is right air conditioner to be installed a per your room specifications.

As different sizes of Air conditioner available in market like 0.8 Ton, 1 Ton, 1.5 Ton, 2 Ton, 2.5 Ton, 3 Ton, 3.5 Ton. so we have to choose one particular Ton of AC as per specifications of rooms.

How to calculate AC tonnage for room

The actual method of finding AC tonnage for room is very confusing as it consists of British thermal unit (BTU) 1 Ton equals 12000 BTU. but here we tell you the simple method to find out the AC tonnage for room, firstly we have to find out the volume of room now the question arises how to find out the volume of room which is very simple.

Volume = (Length * Breadth * Height) in cubic feet

Room Design

As shown above this is design showing the room, here l indicates the length of room now you have to simple measure the same length of your room with the help of measuring tape in feets. b donates the breadth and h donates the height of room. so you have to measure all the three dimensions of room and calculate volume in cubic feet.

Once you calculate the volume of room Divide the volume of room by 1000 and you will get AC tonnage required for room size.

Also Read :

This is not the exact AC tonnage required for room as there are also various other factors affecting the ac capacity required for your room listed below:-

  • Whether Direct sunlight falling on your ceiling (because if you are living on top floor then direct sunlight strikes on your ceiling on the other hand if you are living in ground floor and its a double story house i.e. there are floor above that room then sunlight don’t strikes directly over the ceiling.
  • The place you live is very hot or moderate type climate.
  • The Positioning of windows of room.
  • Number of people residing in the room

The table below shows the right AC tonnage required for your room. While preparing this table we have assumed-

  • 3-4 people residing in the room
  • Average height of room from floor to ceiling is 10 feet.
Area of RoomCooling RequirementRecommended AC Tonnage
100 Sq ft0.9 tons1 ton ac
120 Sq ft1.0 tons1 ton ac
150 Sq ft1.3 tons1.5 ton ac
160 Sq ft1.4 tons1.5 ton ac
170 Sq ft1.5 tons1.5 ton ac
200 Sq ft1.7 tons2 ton ac
250 Sq ft2.1 tons2 ton ac
300 Sq ft2.6 tons2.5 ton ac
400 Sq ft3.4 tons3.5 ton ac

Here we didn’t consider direct exposure of sunlight to ceiling and room walls from south west, so Recommended AC Tonnage can change with these variations.

The Thumbrule for calculating these factors also are as follows-

  1. Add 0.10 ton to cooling requirement, if you are living in hot place.
  2. Add 0.20 ton to cooling requirement, if there is direct sunlight exposure to ceiling of room.
  3. Add 0.10 ton to cooling requirement, if walls of the room are exposed to sunlight from south-west direction.

So If area of your room is 120sq.ft then as per above table cooling requirement is 1.0 ton, but now if there is direct exposure of sunlight to ceiling and wall exposed to south-west direction and also place you live is hot then cooling requirement for room increases from 1.0 ton to 1.4 ton and hence you have to invest in a 1.5 Ton AC.

Now we have explain each aspect of finding out the AC tonnage required for room Now if again you find it difficult to calculate the AC Tonnage then you can use below Calculator to find out the AC Tonnage, you have to just fill the necessary details asked by the calculator and then click on calculate and you will get cooling requirement along with AC Tonnage required for room.

Calculator

I hope you like this article and get complete information regarding AC Tonnage requirement for room, if any queries you can feel free to contact us.