What are stray load losses?

What are stray load losses?

Standards report us that the stray-load loss is that portion of losses in a machine not accounted for by the sum of friction and windage, stator I²R loss, rotor I²R loss and core loss.

What are the losses that occur in DC machines?

The losses that occur in a DC Machine is divided into five basic categories. The various losses are Electrical or Copper losses (I2R losses), Core losses or Iron losses, Brush losses, Mechanical losses, Stray load losses. These losses are explained below in detail.

What is stray loss in generator?

Stray losses are caused by the magnetic leakage and fringing flux in the rotating machine, and their prediction is subject to uncertainties in the machine design. A 750 HP experimental machine has been designed, constructed, and extensively instrumented and tested for direct measurement of the loss components.

What combination of losses is called the stray load loss?

Stray load loss: The combination of friction losses due to moving of bearing and shaft and windage losses due to air gap is called stray loss.

How are stray losses calculated?

The stray losses are calculated under short-circuit conditions. It involves an assumption that the total flux is leakage flux; the core acts as a magnetic screen for setting zero magnetic potential as a boundary condition (magnetic box) in the field model.

What is eddy current losses?

Eddy current loss is conductive I2R loss produced by circulating currents induced in response to AC flux linkage, flowing against the internal resistance of the core.

What power is lost in the stator?

Motor power flow Power is then lost in the stator circuit, and the stator core. The remaining power is transferred to the rotor. Deducting the rotor losses, one obtains the power converted to the mechanical system.

What are constant losses?

As iron core of the armature is rotating in magnetic field, some losses occurs in the core which is called core losses. Normally, machines are operated with constant speed, so these losses are almost constant. These losses are categorized in two form; Hysteresis loss and Eddy current loss.

What is typical transformer losses?

Transformer losses are a combination of core losses and coil losses. These coil losses make up the difference between the 0.5% losses for the core and range from 1.5% to 2% of the total load. Typically, the total losses for a 75 kVA transformer are about 1,000 W at 35% loading or 1.3%.

Why do eddy current losses occur?

When an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to Faraday’s Law of Electromagnetic induction. They will occur when the conductor experiences a changing magnetic field. …

How can we reduce eddy current loss?

Eddy current magnitude can be reduced by designing the core as a set of thin sheets or laminations, in parallel to the magnetic field. Each sheet must be insulated from its neighbours with a thin coating of varnish or oxide film. By laminating the core, the area of each section and hence the induced EMF is reduced.

What are stray losses in a DC generator?

In many of the d.c machines, stray losses are considered as a convention to be 1% of the whole load resultant power. Both the mechanical and the iron losses are collectively termed as stray losses. To know clearly about these losses either in a dc motor or dc generator, the best approach is to follow the power flow diagram.

What kind of losses occur in stray load losses?

The losses occurring in the moving parts of the machine and the air present in the machine is known as Windage losses. These losses are very small. These losses are the miscellaneous type of losses. The following factors are considered in stray load losses.

What kind of loss occurs in a DC machine?

Electrical or Copper Losses in dc machine These losses are also known as winding losses as the copper loss occurs because of the resistance of the windings. The ohmic loss is produced by the current flowing in the windings.

What is stray loss in an induction machine?

For Synchronous and Induction Machine, Stray Load loss is taken around 0.5% of their rated output. Mechanical Loss in Electrical Machine: Mechanical Loss in an Electrical machine basically consists of Bearing friction, Brush friction and Windage loss.