Explain the relationships among speed, frequency, and the number of poles in a three-phase induction motor

1 answer:

5 0

The synchronous speed (rpm) equals 60 times the frequency divided by the number of pole pairs. For 50Hz, a two-pole motor will have a synchronous speed of 3000 rpm, a four-pole motor of 1500 rpm.

The actual speed is a few percent lower due to the slip of the asynchronous motor.

The slip increases with the torque, typical values are 5–10%. The rated speed for a four-pole motor at 50Hz will thus be something like 1360 rpm. At no-load, the slip is very small.

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In monopolistic competition, if a firm advertises and effectively raises consumer awareness of its product, it tends toA) lower

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Answer:

B) raise costs and increase demand for its product

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The increase in unemployment that occurs during recessions and depressions is called Group of answer choices normal unemployment

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Answer:

cyclical unemployment.

Explanation:

Unemployment rate refers to the percentage of the total labor force in an economy, who are unemployed but seeking to be gainfully employed. The unemployment rate is divided into various types, these include;

I. Cyclical unemployment rate (CU).

II. Frictional unemployment rate (FU).

III. Structural unemployment rate (SU).

IV. Actual unemployment rate (AU).

V. Natural Rate of Unemployment (NU).

A cyclical unemployment can be defined as a type of unemployment which is typically related to changes in the business, economy or industry cycle such as recession, governmental policies etc.

Mathematically, cyclical unemployment rate can be calculated using the formula;

$Cyclical \; unemployment \; rate \; (CU) = Actual \; unemployment \; rate \; (AU) - Natural \;unemployment \; rate \; (NU)$