- Domeniu: Electrical equipment
- Number of terms: 4774
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A small generator normally used as a rotational speed sensing device. Tachometers are typically attached to the output shaft of DC or AC inverter motors requiring close speed regulation. The tachometer feeds its signal to a control which adjusts its output to the DC motor or AC inverter motors accordingly (called "closed loop feedback" control).
Industry:Electrical equipment
Has direct bearing on the life of a given motor and when considering life expectancy, the following application considerations that affect the motor's operating temperature, should be taken into account
1. Bearing
2. Lubricants
3. Duty Cycle
4. Radial Loading
5. Axial Loading
6. Mounting
7. Enclosure
8. Ambient Temperature
9. Ventilation
As a general rule of thumb each 10fC increase in total temperature over the maximum permissible to the motor insulation system halves its life. Bearing or gear lubricant life is halved for every 25fF (approx. 14fC) increase in temperature. Heat eventually causes deterioration of most lubricants and seals leading to leakage and increased friction.
Industry:Electrical equipment
Some of the electrical energy losses inherent in motors are converted to heat causing some of the motor parts to heat up when the motor is running. The heated parts are at a higher temperature than the air surrounding them thereby causing a rise above room (ambient) temperature.
It is important to match the proper motor and insulation system (NEMA temp. codes) to the appropriate ambient temperature. If a motor has been built with greater than 1.0 service factor then it can run at a temperature some what higher than the motor's rated operating temperature. In all cases, the actual insulation thermal capability usually is higher than the motor's operating temperature to allow for any excessive heat areas. This is called hot spot allowance. (See Insulation Systems for NEMA standard temperature codes.) Each temperature code has an associated temperature rise which when added to the ambient and hot spot should not exceed the temperature handing of the insulation system.
Industry:Electrical equipment
Tests conducted to determine the temperature rise of certain parts of a motor above the ambient temperature, when operating under specific conditions.
Industry:Electrical equipment
A variety of tests are conducted to ensure motor performance, efficiency, and manufacturing integrity:
Industry:Electrical equipment
A complete test is a test which meets the requirements of IEEE-112-1978. It includes the tests conducted in a Routine Test as well as. full-load heat run; no-load current and watts' determination of torques; efficiencies at 125, 100, 75, 50 and 25 percent of full load; power factor at 125, 100, 75, 50, and 25 percent of full load.
Industry:Electrical equipment
A test performed to verify the motor sound level, conducted in accordance with IEEE-85. The tests are performed under no-load conditions in sound room.
Industry:Electrical equipment
A routine test is a basic test done in the factory to the requirements of NEMA MG1, paragraph 12.51 and IEEE-112-1978 and includes the following measurements: no load current/watts; winding resistance; and high potential test.
Industry:Electrical equipment
A witness test is a test performed with a customer representative present.
Industry:Electrical equipment
An inherent overheating protective device which is responsive to motor temperature and which, when properly applied to a motor, protects the motor against dangerous overheating due to overload or failure to start. This protection is available with either manual or automatic reset.
Industry:Electrical equipment
