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speed of a dc motor can be varied by mainly two methods:-
1)field control method
2)armature control method
further ,
field control method can be divided in 3 parts:-
1)field rhestat control method---speed variation is acomplished by means of a variable resistance inserted in series with shunt field
2)reluctance control method---by changing the reluctance of magnetic circuit by choosing right material..
3) field voltage control method-requires variable field voltage supply.
and armature control method can be divided in 3 parts :-
1)armature resistance control---variable resisitance connected in series with armature
2)shunted armature control.
3)armature voltage control.
------------mrityunjay pandey
(kiit university ,btech 2nd year)
Wiki User
∙ 13y ago
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How speed of a squirrel cage induction motor can be varied?
There are two ways of changing the speed of AC motors,by altering the frequency or the number of poles in the motor. An increase in frequency of the supply voltage to the motor will cause it's speed to increase while reducing the frequency will causes the motor speed to drop. This is the method exploited by Variable Speed/Frequency Drive. The second method of changing the number of motor's stator poles is the difficult. The manufacture must design the motor such that the number of the motor's pole in operation can be increased or reduced. Increasing the number of poles increases the stator flux density which decreases the speed. Decreasing the number of poles does the opposite. This method is typically found in two speed motors and it's rarely used compared to VSDs.
How two speed motor work?
there is two winding is there, one for slow speed , another for fast speed, but both are not variable, but is constant speed. If you use inverter, High speed wingding used for inverter connection .
What is the rotor speed of synchronous motor?
It depends on the number of poles and the frequency of the power. A two pole motor running on 60 Hz would rotate at 1800 RPM.
Why the speed of synchronous motor is independent of load torque?
because we two different supply i.e a.c to the stator of synchronous motor and d.c to the rotor,hence we basically make opposite polarity by these two supplies.
How many Slip rings in synchronous motor?
If the synchronous motor is single phase then there are two slip rings & if this motor is three phase so the slip rings are three in number. Correction; I have never seen a single phase synchronous motor. It would cost more that it was worth. A synchronous motor has a separately excited field. If the excitation comes from a stationary DC source it has 2 slip (collector) rings. A brushless induction motor has no slip rings because the exciter armature rotates and so do the rectifiers. A permanent magnet motor, used with variable frequency drives, is another type of synchronous motor that has no slip rings. A three phase motor with 3 slip rings is a Wound Rotor motor. Wound rotor motors are variable speed motors that were used for such applications as bridges and cranes before variable speed drives.
How speed of a squirrel cage induction motor can be varied?
There are two ways of changing the speed of AC motors,by altering the frequency or the number of poles in the motor. An increase in frequency of the supply voltage to the motor will cause it's speed to increase while reducing the frequency will causes the motor speed to drop. This is the method exploited by Variable Speed/Frequency Drive. The second method of changing the number of motor's stator poles is the difficult. The manufacture must design the motor such that the number of the motor's pole in operation can be increased or reduced. Increasing the number of poles increases the stator flux density which decreases the speed. Decreasing the number of poles does the opposite. This method is typically found in two speed motors and it's rarely used compared to VSDs.
Is three phase induction motor is a fixed speed motor?
This is a more complicated question then first meets the eye. First, the direct answer. Synchronous or Asynchronous motors can work. However, varying speed in an AC motor can only be done by changing the frequency. This requires the use of a Variable Frequency Drive (Like the Altivar series of drives). A variable frequency drive can create noise on the output, thus you may need filter, and the motor should have inverter duty windings. If the motor does not have inverter duty windings, then you may not be able to reduce the speed much. Also, when running a motor at a slower speed, you will need to determine the minimum speed that will allow proper torque to the load, as well as still maintain cooling of the motor coils. Putting a drive onto a motor may require the assistance of a licensed engineer.
How do you wire a two speed pool motor?
Your pool control system must be capable of handling a two speed motor. You'll have to go to the manual to determine connections for your specific motor and controller. You can't effectively use a two speed motor if your control system is not designed and programmed for such a motor.
How many contactors are required for two speed motor?
two
Replace two speed electric motor with single speed electric motor?
Replace with single speed of the same electrical, speed, and mechanical considerations for mounting, choosing the preferred speed from the existing two speed. In general it is common practice especially in the HVAC industry to replace a three speed motor with a four speed motor, using only three of the speeds that match the existing. Replacement must be with a single speed of the same horsepower, torque, and other electrical considerations of the needed or preferred two speed choice of speeds. Often the choice of speed, changes the horsepower or torque.
What is latency speed?
CAS and RAS Latency are two ways of measuring speed
What are two ways that a force can change speed?
friction \
Two ways to change velocity?
speed and direction
What are two ways to know when to shift?
engine speed (rpm) road speed (mph)
How two speed motor work?
there is two winding is there, one for slow speed , another for fast speed, but both are not variable, but is constant speed. If you use inverter, High speed wingding used for inverter connection .
What the two ways of latencys measure speed?
Cas & ras.
Why the DC motor is call as synchronous motor?
A 60Hz synchronous motor spins at synchronous speed - if it's a two pole motor it will spin at exactly 1800 rpms. An asynchronous motor will spin at a speed lower than the power supply frequency - a symilar asynchronous motor may spin at 1700 rpms.
