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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 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 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?
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
Which of the following statements is/are correct with respect to a Scott-connected transformer? I. It can do 3-phase to 2-phase conversion II. It can do 2-phase to 3-phase conversion III. It can do 2-phase to 4-phase conversion IV. It can do 3-phase to 4-phase conversion
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.
The network formed by resistors and capacitors for modifying the rate of change of gain and the phase shift is called a compensating network. Which of the following statements are not correct ? (A) The main purpose of a compensating network is to modify the performance of op-amp ciruit over the desired frequency range (B) There are two types of op-amps : internally compensated and externally compensated (C) 741 C is an externally compensated op-amp while 709 C is internally compensated op-amp (D) The phase lag and phase lead are most commonly used compensating networks in op-amps (E) Phase lag contributes a positive phase angle and phase lead a negative phase angle Choose the most appropriate answer from the options given below : 
Consider the following statements: 1. A synchronous motor has no starting torque but when started it always runs at a fixed speed. 2. A single-phase reluctance motor is not self-starting even if path for eddy currents are provided in the rotor 3. A single-phase hysteresis motor is self-starting Which of these statement(s) is/are correct?
An 3 phase alternator star connected 400 V synchronous motor takes a power input of 5472 watts at rated voltage. Its synchronous reactance is 10** per phase and negligible resistance. If its excitation voltage is adjusted equal to the rated voltage of 400 V, its power factor is _______
If one-phase of a 3-phase synchronous motor is short-circuited, motor