In most of the industry today induction motors are used. Following are some of the main advantages and disadvantages of 3 phase induction motor discussed in detail.
Advantages of Induction Motor:
The advantages of 3 phase induction motor are:
- The very first advantage of an induction motor is that it has a very simple construction. The stator construction is similar in both asynchronous motors and synchronous motors. In rotor construction, slip rings are used in synchronous motors to feed DC supply while in induction motors squirrel cage rotor winding’s are shorted.
- The three phase induction motors are self starting. It means only AC excitation is required to operate the induction motor and no DC excitation is used like we use in a synchronous motor.
- The induction motor is proved to be a robust motor. That is because of their sturdy structure. It can operate in a variety of environmental conditions.
- Less maintenance is required for the induction motor as compared to others like in a DC motor there are carbon brushes which wear and tear and hence we have simple less maintenance motors.
- The cost of these motors is low as they do not have carbon brushes, commutators and slip rings. The absence of these parts makes them very cheap as compared to the other motors.
- There are no sparks in the operation of motors simply because they don’t have any brushes which can cause fatal sparking. Due to this advantage, they can be used in hazardous conditions like in the explosive or polluted environments.
- They are being used to operate in a wide range of industrial applications.
- The 3 phase induction motors have overall good speed regulation and overload capacity.
- Induction motors are highly efficient machines. Their efficiency at full load ranges from 85 to 95%.
- The working of an induction motor is very simple as a 3 phase motor is self starting and does not require any special mechanism for it’s starting. However, the single phase motor requires a capacitor for it’s starting.
Disadvantages of Induction Motor:
The disadvantages of 3 phase induction motor are:
- The induction motors have a poor starting torque. As a result, they draw inrush currents causing momentary voltage drop. So the motor is not suitable for high power applications like traction systems etc. In the slip ring induction motors the starting torque is comparatively better due to the presence of resistance in the circuit of rotor.
- Squirrel cage induction motors have very poor power factor at low load. Upon starting the motor draws high magnetization current to overcome the air gap reluctance present between the rotor and stator. Poor power factor leads to increase in copper losses. Hence, reducing the overall efficiency. To compensate this we make the use of capacitors.
- The speed is difficult to control in an induction motor. This is because a three phase induction motor is a constant speed motor. Hence for applications where fine speed control is needed, dc motors are used instead of induction motors. Nowadays, VFD’s are used for controlling speed in induction motors.
- a single phase induction motor is not a self start motor like the three phase induction motor,and it requires a capacitor in it’s auxiliary winding to start.
These are some of the advantages and disadvantages of induction motor that we have to cope with.