Engines Lubrication

The purpose of lubrication in electric motors is to reduce friction and internal wear and prevent overheating. The grease serves as a vehicle for the added oil, which does the lubricating functions.

The most frequent failure is not the lack of lubrication, but the excessive lubrication, made with a larger amount of grease than recommended.

Excessive lubrication raises the temperature, due to the great resistance that occurs in the movement of the rotating parts and mainly due to the grease beat, which ends up completely losing its lubrication characteristics.

This can cause leakage and penetrates the grease inside the engine and depositing it on the coils or other parts of the engine. The grease used in the motors 1125-5-100-A is polyurea grease specially developed for electric motor bearings.

This grease has good compatibility with conventional lithium greases, but it is not recommended to mix greases, and if you use another type of grease, consult the manufacturer.

For motors with shielded type bearings there is no need for relubrication since they have been factory lubricated for their normal life and use polyurea grease.

Determination of Series Impedance

For the determination of the series equivalent impedance of transformers, the short-circuit test is used and the same procedure will be applied to the autotransformers, with some small differences.

Determining the serial impedance of a three-terminal autotransformer, primary, secondary, and tertiary, is more common than that of only two windings. When an autotransformer does not have a tertiary winding, the test is done in the same way as in the conventional transformer.

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As the equipment has three windings, three “binary” tests, ie a short test between the primary and the secondary with the tertiary open, a test between the primary and the tertiary with the secondary open and a test Between the secondary and the tertiary, with the primary open.

For the conventional transformer it is not possible to determine the value of the impedances of each of the separate windings by the short-circuit test, and so we find that Z1 = 2Z ‘= 0.5 Zeq, however, in the autotransformer test Possible to generate the impedance of each of the windings separately.