750 rpm. As Ns = 120f/P

Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor. ...

If we change the excitation of synchronous machine will it affect on motor speed? Answer : No, If we change the excitation of synchronous machine it will not affect on motor speed. ...

A synchronous motor has better power factor as compared to that of an equivalent induction motor. Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field. ...

Answer : The operating speed of a synchronous motor can be changed to new fixed value by changing frequency. ...

Which motor have more efficiency, synchronous motor or induction motor? Answer : Synchronous motor has more efficiency. ...

Answer : Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed. ...

Answer : If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in damage to the starting winding. ...

Synchronous motor always runs at which speed? Answer : Synchronous motor always runs at synchronous speed....

Why the speed of synchronous motor is constant?

The speed of a three-phase induction motor is controlled by variable voltage variable frequency cont Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases ...

Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor. ...

speed control methods of three phase induction motor? Answer : Speed control of three phase induction motor...

What will happen if the induction motor runs at synchronous speed ? Answer : Since there is always slip present in rotor it cannot run at synchronous speed no current will be developed hence no torque will developed...

What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and Answer : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these ...

The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be? Answer : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4. ...

Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop. ...

what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconn Answer : When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop....

A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by Answer : 0...

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW Answer : An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is 83.33 kW ...

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 p Answer : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu ...

Basic electrical engineering Answer : To find the stator field of a three-phase induction motor, we need to determine the synchronous speed of the motor. The synchronous speed (\(N_s\)) can be calculated using the following formula: \[ N_s = \frac{120 \times f}{P} \] where: - \(N_s\) is the synchronous speed in RPM (revolutions per mi...

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for Answer : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles ...

If the field of synchronous motor is under excited, power factor will be? Answer : If the field of synchronous motor is under excited, power factor will be lagging. ...

With a neat sketch give the working of shaded pole induction motor. Answer : Explanation: It has squirrel cage rotor and salient pole stator. The stator poles are shaded partially by short circuited conductor band to create the phase difference between the fluxes emerging from shaded and un-shaded portion. These phase differing fluxes produce the required torque on the rotor...

The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is Answer : The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is 4 percent ...

The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min (A) 100 rpm (B) 200 rpm (C Answer : The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min 200 rpm ...

If the load of the normally excited synchronous motor is increased the power factor will? Answer : If the load of the normally excited synchronous motor is increased the power factor will become lagging. ...

The synchronous motor will develop maximum power when the load angle is? Answer : The synchronous motor will develop maximum power when the load angle is 900. ...

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inse Answer : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω ...

Answer : The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%. ...

Answer : In case one phase of a three-phase synchronous motor is short-circuited the motor will not start. ...

The maximum constant load torque under which a synchronous motor will pull into synchronism at rat Answer : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque. ...

The maximum torque which a synchronous motor will develop at rest for any angular position of the Answer : Stepper motors are widely used for several reasons: 1. **Precision Control**: Stepper motors move in discrete steps, allowing precise control over position without needing feedback mechanisms. 2. **Open-Loop Operation**: They can operate in an open-loop control system, meaning they do not require ...

Three phase synchronous motor will have how many sliprings? Answer : Three phase synchronous motor will have two sliprings. ...

A change of 4% in the supply voltage to an induction motor will produce a change of approximately Answer : A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque ...

In an induction motor if the flux density is reduced to one-half, of its normal value then the torqu Answer : In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth ...

Answer : If starting winding of a single-phase induction motor is left in the circuit, it will draw excessive current and overheat. ...

Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase. ...

Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly. ...

The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) un Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque ...

A three-phase synchronous motor connected to ac mains is running at full load and unity power factor Answer : Leading...

The synchronous motor which works on leading power factor and does not drive any mechanical load is Answer : The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser. ...

How can we improve power factor using synchronous motor? Answer : Improving power factor using a synchronous motor involves operating the motor in a specific way to provide reactive power compensation to the electrical system. Here are the steps and principles involved: ### 1. Understanding Power Factor and Reactive Power - **Power Factor (PF)**: It is the ratio ...

Answer : Yes, we can make the power factor of synchronous motor leading by adjusting its excitation. ...

Answer : An induction motor has relatively high power factor at near full load. ...

Explain energy conservation technique “by improving power quality” for induction motor. Answer : Energy conservation method in induction motor by improving power quality: Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage unbalance, maintaining voltage & frequency value and avoiding harmonic distortion. i) Voltage unbalance: Three...

Answer : The power factor of a single-phase induction motor is usually lagging. ...

At which time power factor of the induction motor is low? Answer : The power factor of the inducction motor is low at the time of starting as compare to while the induction motor is running. ...

What is back EMF of synchronous motor? Answer : Back EMF (Electromotive Force) in a synchronous motor refers to the voltage generated by the motor's rotating magnetic field as it turns. Here's how it works: 1. **Synchronous Motor Operation**: A synchronous motor operates at a constant speed, known as synchronous speed, which is determined by the...

Why starter is required for starting an induction motor?

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