Types Of Single Phase Induction Motors

There are five types of single phase induction motor they are

a, Split phase induction motors,
b, Capacitor start induction motors,
c, Capacitor start and run induction motor,
d, Shaded pole induction motor,
e, Repulsion start induction motor.
Of these ,the first three are most commonand so we shall discuss them only in here.

a, Split phase induction motor

We know that normally in all single phase induction motors ,there are two windings namely starting winding(auxillary winding) and running winding(main winding), these two coils are connected in parallel in the split phase induction motor.the centrifugal switch is normally closed and when the motor is started and reaches 80% of its full speed ,the switch opens to disconnect the starting winding which is connected in parallel to the running winding by means of a centrifugal switch. Starting coil has high resistance and low inductive reactance,whereas running coil has low resistance and high inductive reactance.The current on both the starting and running coils are lagging in nature.The phase angles between the starting and running coils is 40-50 degrees.The torque in this motor is low.Its effeciency is around50%.

Applications

Fans,pumps,blowers,etc

b,Capacitor start induction motor

Here the capacitor is aditionally added in between the centrifugal switch and starting winding,because of the addition of capacitor the output power is increased phase angledifference between starting and running coils is approximately 90 degrees power factor is increased due to the addition of capacitor,starting torque is increased and effeciency is also increased.starting current leads the running currrent effeciency is around 55%,starting torque is 350 times of full load torque.

Applications

Compressors,conveyors,air conditioners,etc

c,Capacitor start and run induction motor

Incase of capacitor start motor the capacitance is at the time of starting only and ant the time ofrunning at full speed(rated) it is cut off,but here the capacitor runs till the supply is turned off and so there is an improved effeciency,(i.e) its effeciency is around 65-70%,starting torque is equal to200% full load torque.power factor too increases.

Applications

Washing machines,refrigrators,cooling fans,etc,besides this these motor can be used in all applications of split phase and capacitor start motors.

Applications of LED

The LED's are of different colours such as red,green,blue,yellow,green,etc.They found a wide applications extensively in almost all display boards.the main application is that it is used in seven segment displays,which are used widely in digital indication applications.There are two types of seven segment display's namely
1.Common anode type,and
2.common cathode type.
In the common anode type,the anodes are sort together and a supply of 5v is given and the cathode terminals are connected to the ground,so that the LED's may glow.
And in the common cathode type,the cathode's are sort together and is given to ground,the anode terminals are provided with the supply.
Mostly seven segment display's are used in traffic signal lighting,digital measuring instruments,etc.
Apart from this the LED's are also used in the back-lighting of LCD monitors.

Switches

Toggle Switches


These switches are used in simple applications say two modes and are used mostly in machines were we need a constant switching between two modes.

Selector Switches:

These switches surf between a large number of modes, a simple example of selector switch is a type of ordinary electric fan regulator switch which switches between a wide range.

Drum Switches:

These switches commonly are power supply switches,since they are mostly used to switch ON lathes and drilling machines.They are also used to switch motors to run at forward or in reverse direction.

Rotary Switches:

They perform switching operation throughout 360 degrees example a type of ordinary electric fan regulator switch which rotate 360 degrees.

Limit Switches:

These switches are used to protect a machine part from exceeding its axial distance in case if the part runs off the limit the switch reverses the direction of the part by reversing the direction of rotation of the prime mover mostly a motor.It is actuated by machine part touching it's lever.

Push Button Switches:

These switches are used to control a function either switching 'on' or 'off'.They are mostly used in conventional lathes.

Membrane switches

These switches are of typical use they are used in the contol panel of CNC machines to denote the alpha numeric characters they give a membrane coating to the buttons(switches).