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Why the synchronous motor is always a salient pole machine ie why don't we use a cylindrical pole machine as a synchronous motor?
The speed of the machine is tied to the power supply frequency and the number of poles the machine has. It becomes impractical to make a round rotor machine with many poles, so machines that spin at low revolutions will typically be salient designs. A two or four pole machine could be round rotor designs.
What else can I help you with?
Why a machine should run with synchronous speed?
A synchronous motor is not self starting.However when it is provided with some prime mover ,which rotates it up to 80% of sync. speed,then it continues to rotate at sync.speed even after prime mover is removed.It happens so because rotor poles are locked with rotating magnetic field and hence the speed is always synchronous.
Why do you use induction generators in wind generation rather than synchronous generators?
If you use synchronous generator... you need rotor to rotate always in synchronous speed... practically it s not possible always to produce that speed by air flow... Air flow always varies...But using induction generator, you need to get speed to make slip as positive value.. it is always possible...so induction generator is best one..
How many types of winding are used in AC and DC motors?
IN DC MOTORThere are 2 types of windings:1. Field windingOn poles core which are on stator body.These are always concentrated type.2. Armature windingOn rotor on motor may be simplex or multiplex and lap or wave connected.IN AC (Synchronous ) MOTOR3-phase star or delta connected on stator (armature ) suppliedby 3 phase may be concentrated or distributed (usually preferred) .Rotor (field ) has concentrared in salient pole type nd distributed in cylindrical type supplied by DC supply.IN AC ( Induction ) MOTOR3-phase (star or delta connected) distributed winding on stator and wound rotor .In squirrel cage rotor short circuted copper bars are used.
Why a normal machine could not have the mechanical efficiency of 100?
Because there is always going to be friction, the efficiency of any machine will always be less then 100 percent.
Why induction motor speed is always less then synchronous speed?
induction motor never runs at synchronous speed, if it does so there would not be any relative speed between stator flux and rotor and no emf will induce in rotor and we can not apply motor principle as we need current carrying conductor in magnetic field.
Why a machine should run with synchronous speed?
A synchronous motor is not self starting.However when it is provided with some prime mover ,which rotates it up to 80% of sync. speed,then it continues to rotate at sync.speed even after prime mover is removed.It happens so because rotor poles are locked with rotating magnetic field and hence the speed is always synchronous.
Why single phase induction motor always runs below the synchronous speed?
For exactly the same reason as three-phase motors always run below synchronous speed. If they were to run at synchronous speed then no voltage and, therefore, no rotor current will be induced into the rotor to drive it.
Why do you use induction generators in wind generation rather than synchronous generators?
If you use synchronous generator... you need rotor to rotate always in synchronous speed... practically it s not possible always to produce that speed by air flow... Air flow always varies...But using induction generator, you need to get speed to make slip as positive value.. it is always possible...so induction generator is best one..
Explains why a 3-phase induction motor develops no torque when running at synchronous speed?
When rotor speed becomes equal to Synchronous speed in an induction motor, it means that the slip is zero. Which means that there is no cutting of magnetic lines by rotor bars and hence no torque is generated. To generate Torque, rotor speed should always be less than the synchronous speed. That is why, you must have seen in your dailty life that all induction motors are rated below 3000 RPM(sync speed for a 2 pole machine). Sync speed (Ns) = 120f/P
Equal periods of rotation and revolution of the moon cause what?
Cause us to always see the same "face" of the moon. This is called synchronous rotation.
When periods of the moons rotation and revolution are equal what is it called?
It is called synchronous rotation when the rotation and orbit take the same amount of time.
What is a synchronous rotation?
A synchronous rotation is when an object's rotation period matches its orbital period, causing the same side of the object to always face its orbiting body. This is commonly seen in moons orbiting larger planets, such as Earth's moon.
Why in a real machine the output work is always less the input work?
In a real machine, part of the energy (or power) is always wasted.
The mechanical advantage of a machine is always greater than 1?
well the advantage of that is pie, not math pie but pie that you eat
State at which the moon's orbital and rotational periods are equal?
Synchronous rotation occurs when the moon's orbital period (the time it takes to orbit the Earth) and rotational period (the time it takes to rotate on its axis) are equal. This means that the same side of the moon always faces the Earth.
How many types of winding are used in AC and DC motors?
IN DC MOTORThere are 2 types of windings:1. Field windingOn poles core which are on stator body.These are always concentrated type.2. Armature windingOn rotor on motor may be simplex or multiplex and lap or wave connected.IN AC (Synchronous ) MOTOR3-phase star or delta connected on stator (armature ) suppliedby 3 phase may be concentrated or distributed (usually preferred) .Rotor (field ) has concentrared in salient pole type nd distributed in cylindrical type supplied by DC supply.IN AC ( Induction ) MOTOR3-phase (star or delta connected) distributed winding on stator and wound rotor .In squirrel cage rotor short circuted copper bars are used.
Why a normal machine could not have the mechanical efficiency of 100?
Because there is always going to be friction, the efficiency of any machine will always be less then 100 percent.
