Hello friends, today I am going to tell you ** Selection of specific electrical loading and magnetic loading**: If you also want to know, then keep reading this article completely.

## Selection of Specific Electric Loading

The following factors play an important role in selecting the specific electrical loading:

**(1) Temperature Rise –** The temperature of the windings increases substantially for higher values of specific electrical loading. The use of insulating materials allows us to use high specific electrical loadings for machines. The cooling system of the machine must be taken into account when selecting high loadings. In machines that have good cooling, the value of the ampere conductor is taken more. If the cooling coefficient of the machine is low, the value of the specific power loading can be used. With the machine having good ventilation, a low value of cooling coefficient and a high value of specific power loading can be used.

**(2) Speed of Machine –** If the speed of the machine is high and the machine’s ventilation is good, then high losses can be dissipated. Therefore, high-speed machines can be used for high-value specific power loadings.

**(3) Voltage –** More space is required for the insulator in high voltage machines, so there is less space for the conductors. The increase in voltage leads to a decrease in the normal and specific electrical loading, so for high voltage machines, the value of the specific electrical loading is taken as low.

**(4) Size of Machine-** Drivers can be easily arranged in large machines. Therefore, the machine with a larger diameter has higher specific power loading.

**(5) Armature Reaction –** If we take the value of specific electrical loading high, then the value of armature mmf is high, or in other words, armature becomes magnetically powerful. Due to this, the flux generated by the field of the machine in the event of load on the machine, there is more desaturation. As a result, the amount of flux in the air space decreases. To overcome this effect, the number of turns in the field winding of the machine has to be increased, and the cost of the machine increases. Hence it is taken care of while selecting the specific power loading.

**(6) Commutation –** The difficulty in commutation is due to the generation of more reactance voltage during commutation by taking more specific electrical loading. Hence the value of specific power loading should be less from the point of view of commutation.

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## Selection of Specific Magnetic Loading

The selection of specific loading is affected by certain factors. Many of these factors are general, applicable to all types of machines, and many of these factors are specific, only to single machines. Here D.C. We will study the factors affecting the loading of the machine. In general, the following factors affect the specific magnetic loading:

**(1) Flux Density in Iron Teeth of Armature –** Let the maximum value of flux density for the air gap, then the maximum value of flux density in the armature teeth will also be obtained. The maximum flux density (E) occurs in the armature teeth, where the width of the tooth is the least. The value of the air gap density is selected so that the value of the flux density at the root of the tooth does not exceed 2.2 teslas (Tesla = Wb/m2). Otherwise, the value of MMF required for the teeth will be greatly increased. The flux density in the iron part is proportional to the average flux density in the air space. If the flux density exceeds the specified, the iron losses in the ferrous parts of the machine increase.

**(2) Magnetising Current –** The magnetizing current of the machine is directly proportional to the mmf required to exert a force on the iron parts of the machine and the flux through the air gap. The mmf required for an air gap is directly proportional to the flux density in the gap. It is observed that the value of flux density for iron parts depends on the specific magnetic loading. On selecting a low value of specific magnetic loading, the flux density in the iron parts is low, so these parts act on the knee part in the linear or B-H curve. Values of MMF are low or almost negligible for iron parts, e.g., linear for H or in B-H curves, the values of mmf per meter length on flux density in knee parts are very low.

When the value of specific magnetic loading is high, the flux density in the iron parts acts so that these parts are in the saturation region in the B-H curve, due to which the per unit length is very large. Therefore, the value of magnetization mmf increases due to specific magnetic loading, and the value of magnetizing current is high.

**(3) Frequency –** When the machine‘s armature rotates, the magnetic circuit of the armature comes alternately (one after the other) under the influence of the north and south poles. The frequency of the reversal is f=pn/2. If the reversal frequency is high, the iron losses in the armature and teeth will also be high, so the value of high flux density in the machine’s air gap is not used.

**(4) Size of Machine –** The size of the machine increases as the value of flux density in the machine increases. As the value of diameter (D) of the machine increases, the width of the teeth of the machine increases.

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Now you must know* Selection of specific electrical loading and magnetic loading?*