Magnetism

Magnetism basically consists of lines considered impossible to be seen of forces created by types of natural magnets and also by the known as electromagnet.

Among the most common types of natural magnets, the three main ones are the needle found in the compass, the horseshoe used in animals, and the bar. The magnets have two main specifications, they can attract and attach to any material containing iron, and if they are free to move, such as the compass needle, for example, have the ability to point to the north or south.

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In electric motors, each magnet has two poles, one is the north pole and the other is the south pole. The lines impossible to be seen in the magnetic flux leave the north pole and go towards the south pole. Just as the flow lines are invisible, the effects of the magnetic field created by them, depending on the situation, may even become visible.

If a sheet of paper is placed on a natural magnet or an electromagnet, and iron filings are placed on it, the iron filings may be deposited along the invisible lines of the stream.

Motors with and without grease

In greaseless electric motors, lubrication must be performed as described in the existing preventive maintenance plan. The disassembly and assembly of this type of motor must be made according to the specifications described by the manufacturer. Electric motors with shielded bearings require their bearings to be automatically replaced when they reach the end of their grease life.

In the case of motors with grease fittings, at the precise moment of relubrication of their bearings with the engine stopped, it is necessary to thoroughly clean the vicinity of the grease entry holes. It is extremely important that approximately half of the recommended total grease is placed on the nameplate of the engine, and thus cause the engine to rotate for about one minute at the rated speed.

The engine must be switched off so that the remaining grease can be put in place and, afterwards, replace the grease guard. For the relubrication process of the bearings at the moment the engine is in operation, it is important that the person responsible for the action is careful to clean the vicinity of the grease entry hole and, as in electric motors without grease. https://www.mrosupply.com/automation/ac-variable-frequency-drive/697987_vs1md43-8_baldor/