The synchronous speed of an AC motor is determined by the supply frequency and the number of poles in the machine. The formula for synchronous speed ($N_s$) is:
$N_s = \frac{120 \times f}{P}$
Where:
- $N_s$ = Synchronous speed in revolutions per minute (rpm)
- $f$ = Supply frequency in Hertz (Hz)
- $P$ = Number of poles
Synchronous Speed Calculation: Initial State
Given initial parameters:
- Frequency ($f_1$) = 50 Hz
- Number of poles ($P_1$) = 4
Calculate the initial synchronous speed ($N_{s1}$):
$N_{s1} = \frac{120 \times 50}{4} = \frac{6000}{4} = 1500 \text{ rpm}$
Synchronous Speed Calculation: Changed Parameters
The problem states that the frequency and pole number are halved. The load torque change does not affect the synchronous speed itself.
New parameters:
- New frequency ($f_2$) = $\frac{f_1}{2} = \frac{50}{2} = 25 \text{ Hz}$
- New number of poles ($P_2$) = $\frac{P_1}{2} = \frac{4}{2} = 2 \text{ poles}$
Calculate the new synchronous speed ($N_{s2}$):
$N_{s2} = \frac{120 \times f_2}{P_2} = \frac{120 \times 25}{2} = \frac{3000}{2} = 1500 \text{ rpm}$
Motor Speed Conclusion
After halving the frequency and the number of poles, the new synchronous speed of the motor remains 1500 rpm. For a synchronous motor, the operating speed is the synchronous speed.
Similar Questions
- If $A \in R_{n \times n}$; $\det A=0$, then :
A. A is non singular and the rows and columns of A are linearly independent
B. A is non-singular and the rows and columns of A are linearly dependent
C. A is non-singular and A has one zero rows
D. A is singular
E. A is singular and rows and columns of A are linearly dependent
Choose the correct answer from the options given below : - The matrix equation $AX=0$, represents :
- The greatest rate of increase of $f = xy^{2}z^{3}$ at the point $(0, -1, -2)$ is :
- The derivative of $y = \int_{0}^{\ln x} \sin e^{t} dt$ is :
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- If A is a null Matrix, then its rank is :
- Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : If $u = xy f\left(\frac{y}{x}\right)$, then $x \frac{\partial u}{\partial x} + y \frac{\partial u}{\partial y} = 2u$
Reason (R) : Given function u is homogeneous of degree 2 in $x$ and $y$.
In the light of the above statements, choose the most appropriate answer from the options given below : - Solving a second order Differential equation using Laplace transform :
A. Partial fraction expansion
B. Apply initial conditions in Laplace domain
C. Take Laplace transform of differential equation
D. Obtain time domain solution
Choose the correct answer from the options given below : - Determining Eigenvalues of a matrix :
A. Solve the characteristic equation
B. Form matrix $A - \lambda I$
C. Compute determinant
D. Identify eigenvalues
Choose the correct answer from the options given below : - A lag network for compensation normally consists of :
A. R, L and C elements
B. R and L elements
C. R and C elements
D. R only
E. L only
Choose the correct answer from the options given below :
Important Questions from Mixed Topic (CUET PG)
- Who was the founder of Bolshevik Communist party?
- What is the key guide to statecraft in the realist tradition?
- Chronologically arrange the events in the Cold War period.
A. Berlin Wall is constructed
B. Communist China joins the UN
C. Soviet invasion of Czechoslovakia
D. Berlin Blockade
Choose the correct answer from the options given below: Morgenthau's principles of political realism are:
A. Politics is rooted in permanent and unchanging human nature which is basically self centred, self-regarding and self-interested
B. Politics is an autonomous sphere of action and cannot therefore be reduced to morals
C. International Politics is an arena of conflicting self-interests
D. The ethics of international relations is situational ethics which is very different from private morality
Choose the correct answer from the options given below:Who among the following political thinkers consider the anarchical self help system to be a compelling factor for States to maximise their relative power positions?
