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Consider the following statements regarding synchronous machines: 1. When a synchronous motor is over-excited, its back emf is greater than the supply voltage 2. When a synchronous motor is over-excited, its power factor is leading 3. Synchronous motor is used as capacitor where load is so large that construction of a static capacitor is impractical Which of these statements are correct?
In case of synchronous motor, which of the following are true? a. Synchronous motor is not self-starting b. If the rotor poles are excited by field current and the stator terminals are connected to AC supply, motor vibrates. c. Variable frequency supply is used to start synchronous motor. d. By using frequency converter, a synchronous motor can be brought from standstill to its desired speed.
A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
A three-phase cylindrical rotor synchronous generator has a synchronous reactance Xs and a negligible armature resistance. The magnitude of per phase terminal voltage is VA and the magnitude of per phase induced emf is EA. Considering the following two statements, P and Q, P: For any three-phase balanced leading load connected across the terminals of this synchronous generator, VA is always more than EA Q: For any three-phase balanced lagging load connected across the terminals of this synchronous generator, VA is always less than EA Which of the following options is correct?
Consider the following statements The equivalent emf is equal to the individual emf of the cells in the series combination of cells having the same emf.  The equivalent emf is equal to the individual emf of the cells in the parallel combination of cells having the same emf. Which of the following statement is correct?
A synchronous motor on load draw a current at a leading power factor angle ϕ. If the internal power factor angle which is the phase angle between the excitation emf and the current in the time phasor diagram is ψ. Then the air gap excitation mmf lags the armature mmf by
A synchronous motor is operated at a bus voltage of 1.5 pu and drawing 1.0 pu at zpf leading current. Its synchronous reactance is 0.4 pu. What is the excitation emf of the motor?
A synchronous motor absorbing 60 kW is connected in parallel with an continuous load of 240 kW operating at 0.8 power factor lag.What is the kVAR supplied by the synchronous motor to obtain a total power factor of 0.9 lagging?
Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-connected induction generator. Consider capacitive VAr to be a source and inductive VAr to be a sink of reactive power. Which one of the following statements is TRUE?
Which of the following statements are correct for synchronous motors? 1. Synchronous motors are well-suited for direct connection top reciprocating compressors. 2. Over-excited synchronous motors are most commonly used for power factor improvement. 3. Synchronous motors are generally used for current regulation of long transmission lines Select the correct answer using the code given below.