Difference Between kVA and kW

kVA vs kW

Have you ever noticed that with every appliance or piece of electrical machinery that you avail, they will always indicate their respective power ratings?

You will notice that some electrical equipment express their power ratings in kW, or kilowatts; and some are expressed in kVA, or kilo Volt Amperes. Both values express power, but they are actually different.

kVA is known as the ‘apparent power’ of a particular circuit or electrical system. In direct current circuits, kVA is equal to kW, because voltage and current do not get out of phase. However, ‘apparent power’ and ‘real power’ (which is expressed as kW) may differ in alternating current circuits. kW is simply the amount of actual power that does valid work. It should be noted that only fraction of kVA is accessible to do work, and the rest is an excess in the current.

Solving for the kW (real power) requires another variable called the Power Factor (PF). That so-called Power Factor is a nebulous value that can vary for every appliance or electrical device. In essence, the value of the Power Factor is either given in a percentage, or 0 to 1, wherein 100 percent (or 1) is considered as unity. The closer the Power Factor is to unity, the more efficient a particular device is with its use of electricity.

Unity is practically present in DC circuits, which creates no difference between the kVA and kW. A device uses less kW when the voltage is out of phase with the current. At the same time, the Power Factor naturally lowers in the process. Power Factor will either be leading or lagging, depending on which way the load shifts the phase of the current with respect to the phase of the voltage.

The relationship between the three (kVA, kW, and Power Factor) is mathematically described as:

kW = kVA x Power Factor; kVA = kW / Power Factor; Power Factor = kW / kVA

In DC circuits, the power factor is mathematically inconsequential, because it is in unity. Therefore:

kW = kVA = Volts x Current x 1 = Volts x Current

Summary:

1. kVA is known as the ‘apparent power’, while kW refers to the actual, or real power.

2. kW is the amount of power capable of doing work, while only a portion of kVA is available to do work.

3. kW is kilowatts, while kVA is kilo Volts Amperes.

4. kVA is equal to kW in DC circuits because the voltage and current are not out of phase (unity).

5. However, in AC circuits, voltage and current may get out of phase. Therefore, kW and kVA will differ depending on the Power Factor, or how much leading or lagging occurs.

Read more: Difference Between kVA and kW | Difference Between | kVA vs kW http://www.differencebetween.net/science/difference-between-kva-and-kw/#ixzz3dxOF3nTj

 How a Turbocharger Works

Critical to the Operation of Diesel EnginesAn engine is designed to burn a fuel-air mixture to produce mechanical energy. The mechanical energy then moves pistons up and down to create the rotary motion that turns the wheels of a vehicle. The more mechanical energy, the more power the engine can produce.
A significant difference between a turbocharged diesel engine and a traditional naturally aspirated gasoline engine is that the air entering a diesel engine is compressed before the fuel is injected. This is where the turbocharger is critical to the power output and efficiency of the diesel engine. It is the job of the turbocharger to compress more air flowing into the engine’s cylinder. When air is compressed the oxygen molecules are packed closer together. This increase in air means that more fuel can be added for the same size naturally aspirated engine. This generates increased mechanical power and overall efficiency improvement of the combustion process. Therefore, the engine size can be reduced for a turbocharged engine leading to better packaging, weight saving benefits and overall improved fuel economy.
Although turbocharging is a relatively simple concept, the turbocharger is critical to the operation of the diesel engine and therefore requires a highly engineered component. Our extensive experience in turbocharging technology and knowledge of engines combines for world-class design and manufacture of Holset Turbochargers, renowned for their durability, high standard of safety, and reliable performance that engines demand.
How does a turbocharger work?
A turbocharger is made up of two main sections: the turbine and the compressor. The turbine consists of the (1) turbine wheel and the (2) turbine housing. It is the job of the turbine housing to guide the (3) exhaust gas into the turbine wheel. The energy from the exhaust gas turns the turbine wheel, and the gas then exits the turbine housing through an (4) exhaust outlet area.
(1)  The turbine wheel (2)  The turbine housing
(3)  Exhaust gas
(4)  Exhaust outlet area(5)  The compressor wheel (6)  The compressor housing(7)  Forged steel shaft (8)  Compressed air


















The compressor also consists of two parts: the (5) compressor wheel and the (6) compressor housing. The compressor’s mode of action is opposite that of the turbine. The compressor wheel is attached to the turbine by a (7) forged steel shaft, and as the turbine turns the compressor wheel, the high-velocity spinning draws in air and compresses it. The compressor housing then converts the high-velocity, low-pressure air stream into a high-pressure, low-velocity air stream through a process called diffusion. The (8) compressed air is pushed into the engine, allowing the engine to burn more fuel to produce more power.