Protection electric motors

Experiments for testing the flameproofness of specially protected electrical motors and apparatus and for the determination of suitable safety devices for such apparatus, performed at the Berggewerkschaftliche Versuchsstrecke, Gelsenkirchen-Bismarck... 

Electrical. The plant electrical system is sometimes more important than the steam system. The electrical system consists of the utihty company s entry substation, any ia-plant generating equipment, primary distribution feeders, secondary substations and transformers, final distribution cables, and various items of switch-gear, protective relays, motor starters, motors, lighting control panels, and capacitors to adjust power factor. 

An electric motor must be adequately protected against all unfavourable operating conditions and internal or external faults. We have classified these conditions into three categories to identify the most suitable protection ... 

This may be 50 or 60 Hz as the system may require. The permissible variation may be eonsideied as 2% for measuring as well as protection VTs. These limits are based on the recommended variations applicable for a switchgear assembly (lEC 60429-1) or an electric motor (Section 1.6.2),... 

Part I Selection, testing, controls and protection of electric motors... 

It also deals with electric motors as they are typical for their surge behaviour and protection. 

Part I Selection, Testing, Controls and Protection of Electric Motors... 

The speed of an electric motor can be changed by altering the frequency of the electric current. This is because the ratio is the same as 60 or 50 f/p (f = the frequency of the current, p = the number of poles in the stator). Frequency converters are built of electronic components, frequently combined with microprocessors. They provide good motor protection and are superior to the traditional bimetal protection. The characteristic curve for a pump and fan motor is also quadratic, making lower demands to the frequency converters When the frequency of the electrical current is changed in the frequency converter, the main AC supply is transformed into DC. The DC is then treated... 

See also-. Climatic Effects Consumption Domestic Energy Use Electric Motor Systems Electric Power, Generation of Electric Power, System Protection, Control, and Monitoring of Electric Power Substations Electric Power Transmission and Distribution Systems Government and the Energy Marketplace Regulation and Rates for Electricity. 

Figure 14-2B. Typical Holloshaft construction for vertical induction motor, weather-protected construction. (Used by permission Bui. BR 509-91B 1991, U.S. Electrical Motors, Div. Emerson Electric Co.)...

U.S. market is about 20 million pounds per year. The applications are those where one needs very high flame resistance (clothing for firefighters and welders, welder s protective shield, upholstery and drapes), heat resistance (ironing board covers, insulation film for electrical motors and transformers, aerospace and military), dimensional stability (fire hose, V- and conveyor belts), or strength and modulus (circuit boards, bulletproof vests, fiber optic and power lines, ship mooring ropes, automobile tire cord, puncture-resistant bicycle tires). 

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