Losses In An AC Generator:

We conclude that despite taking utmost care. Minor energy losses are always there in an AC generator. As most of the losses are due to the products' property, the losses can cut, but they never can remove.
diesel generator set

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An AC generator is a machine. It uses its mechanical parts to convert mechanical energy into electrical energy. In an ideal condition, the output provided by the AC generator equals the input.

But, in real-life situations, this is not the case. Instead, the output is always less than the input due to the external effects. The external influences can be manifold. But one thing is for sure:

All the mechanical effort put into use does not convert into electrical energy.

But we can exploit ways and means to maximize the output with the available input. First, we need to understand what causes the loss of power and energy in AC generators.

What are the causes of the losses in an AC generator?

While AC generators are running, different small processes are also occurring. These processes cause energy losses. The common causes of failures in an AC generator are:

  • Power loss
  • Eddy currents
  • Molecular friction
  • Mechanical losses
  • Voltage drop

What causes the power losses in an AC generator?

When the current flows through the wire in a circuit, it opposes its flow as resistance. All cables have some amount of resistance. So the power losses in a generator cause due to the resistance of the wire.

The amount of resistance depends on the following factors:

  • Size of the wire
  • The material of the wire
  • Length of the wire

Because resistance of the wire, the wire causes a loss of some power. As the generator is a sophisticated machine, its coil uses several feet of copper wires. Several feet of wire implies a high amount of resistance.

stator with copper wiring

How to calculate the power losses in an AC generator?

Overcome the power losses, the induced voltage introduce. This results in the heating in the wire windings of the generator. The equation to calculate the power losses is:

P = I2R


P= Power

I= Current

R = Resistance

As we can see, the power is proportional to the current’s square (I). This means that the power losses will be four times (Michael, 2019).

The losses that occur due to the wire windings’ resistance are also called—copper losses for a mathematical equation, I2R losses.

What are eddy currents?
How do they cause energy losses in an AC generator?

Increase the amount of induced current. The armature windings are wound in an iron core. This iron core slot is a way to hold the coils. Like the conductor, when it rotates around the magnetic field, voltage induces in it.

The voltage in the coil causes the flow of alternating current in the core. Alternating current produced in the wave call eddy current. The winds cause power losses in the AC generator by producing extra heat. This excess heat is, in fact, a loss of energy.

How to prevent the loss of energy by eddy currents?

The excess heat produced by the eddy currents can cause the AC generator to stop working. To prevent this, divide the core into segments. Then laminate each component with lacquer or rust. The laminations lessen the voltage produced by the eddy currents. Also, they increase resistance to the power which drain by the eddy currents.

brushless ac generator

What is molecular friction?
How to overcome the energy losses by molecular friction?

When the conductor-coil rotates in a fixed magnetic field, innumerable small particles of the coil get lined up with the area. This divides the countless particles into the ones lined up and the scattered ones.

The scattered ones provide friction to the ones lined up with the magnetic field. This results in internal conflict and the production of heat as a result. This phenomenon call molecular variance. Molecular friction is also called hysteresis.

Cut the losses done by molecular friction, silicon steel use. Care take to ensure that the hysteresis loss of this steely low. This silicon-steel amalgam anneal through a heat process to the core. This prevents the losses from happening again.

What type of mechanical losses are involved in AC generators?
How to minimize mechanical losses in an AC generator?

In all types of mechanical devices, friction is a significant automatic loss. Due to the rotation of the coil, air friction, bearing friction, and brush friction occurs. This friction is an ordinary loss that happens in all kinds of mechanical devices. That’s why you don’t need to worry about them.

These mechanical losses can cut by proper lubrication of the generator. , you should also do adequate brush seating. Reduce the air friction losses; generators come with a hydrogen provision mechanism. As hydrogen is less dense than air, this helps in less windage (air friction) losses.

Also, careful maintenance should do from time to time.     

Image for brushless Alternator

What is the voltage drop? How it causes energy loss in an AC generator?

Before the start of the current flow, the voltage difference is at the highest level. When the current starts to flow, a voltage drop develops between the poles. Due to this, the voltage generation gets lowered. The exact value of this dropped value can tell the amount of the loss that has occurred. The drop can calculate from the following equation:

Voltage drop = IaRa + IaXLa


Ia = Armature (Coil) current
R= Armature (Coil) resistance
XLa = Armature inductive reactance

As we know that in Alternating Current, the direction of the current keeps on changing. Inductive reactance is the property of the AC circuit. It opposes the change in the order of the draft.

How to calculate the efficiency of an AC generator?

Efficiency can calculate when the number of losses. Due to the phenomena mentioned above, find. The efficiency of an AC generator tells of the generator’s effectiveness. In the discharge of its energy production (Thomas, 2018).

Calculated by the ratio of useful power output produced. By the generator to the total input provided to do so.

Even with highly-efficient generators, minor losses are always there. So no generator comes with 100% efficiency.   


We conclude that despite taking utmost care. Minor energy losses are always there in an AC generator. As most of the losses are due to the products’ property, the losses can cut, but they never can remove.

But if you are looking for AC generators with the highest efficiency and durability. Then Bolipower is the answer.

Our generators are not only designed to cater to daily power needs, but also they are efficient with various sizes of high-qualities generators. They can work as power equipment for camping, washing machine, refrigerators, and so on.

With voltage stability, BOLIPOWER generators are efficient to the optimal quality with minimal losses.

As our tagline proclaims, ‘when it comes to reliability, we are the one you need.’

Our various quality generators can see from the link: Generators On Our Website.

Any queries, share them with us by commenting below. And if you want to get a quote, contact us, we will get back to you within 24 hours.

Image for author

Hey all, I'm Baymax Yan, working at a generator manufacturer and Having more than 15 years of experience in this field, and I belives that “learn and lives.” The sure thing is that I can often help my work. So I have created the blog to share all my knowledge with you. Hope my sharing helps!

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