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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.
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 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?
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 thermocouple-based temperature measurement system is shown in the adjoining figure. Relevant thermocouple emf data (in mV) is given below. The cold junction is kept at 0°C. The temperature is 30°C in the other parts of the system. The emf V is measured to be 26.74 mV. Th temperature of the hot liquid is Temp. emf of Chromel- Constantan emf of Copper- Constantan 10°C 0.591 0.391 20°C 1.192 0.789 30°C 1.801 1.196 370°C 26.549 19.027 380°C 27.345 19.638
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?
In a synchronous motor the back emf peak set up in the stator depends on ___________
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.
On which of the following does the back emf set up in the stator of a synchronous motor depend? I. Rotor speed II. Rotor excitation III. Coupling angle Choose the correct answer from the options given below.