SELECTION OF 3 PHASE INDUCTION MOTOR
For selection of
induction motor we have to consider various factor related to safety,
application use, running time etc. Here are some key points that you have to
kept in mind before selecting the motor.
1)
Running Time: - If you have to
run the motor continuously approx. 24/7 then its S1 Duty type motor. Also as
per running time various Duty types motors are available i.e. S1,S2 to S9, etc.
2)
Torque: - If your machine needs
high torque heavy transmission in weight then you have to consider 2 Pole, 4
Pole, 6 Pole Motors which gives speed 3000, 1500, 750 rpm. As pole increased
speed decreases and provides high torque. But if you need more high torque then
you can couple it with gearbox to get desired output torque which we will
covered detailed overview in next blog for gearbox.
3)
Motor speed & control: - To
run the motor at different speed we use VFD (Variable frequency drive)
i.e. by changing the frequencies of motor, we change their speed. Also we can
control various thing i.e. on or off timing and reverse/forward direction. Same
we’ll cover this in detail in our next blog for VFD.
4)
Power: - As per your machine
specification how much HP or KW power is required you have to calculate i.e.
0.5hp, 2hp, 5hp or 2.2KW, 3.7KW etc. so the motor can easily run and gives
continuous motion without overheating and at its higher efficiency.
5)
Mounting Position: - For
fitment basis you have to fix it with flange or foot mounted type. (for ex.
182F means from bottom of base to center of shaft distance is 182 and F is foot
type) or (if it is flanged type then check short flange or normal its OD and
holes PCD matching or not.) with gearbox or mounting position of frame. Keep in
mind as HP increase frame size increases so, size of motor gradually increase
it means you have to consider space constrained in your mounting area is
available or not.
6)
Environmental Condition/ Safety:
- If your motor run in dirty area or oil industries then you have to kept
safety in mind so, select flameproof and dustproof fully closed cooling fan
etc. if high temperature area is there then you have to select force cooling
type motor also. See which IE certification type you get.
7)
Electrical Supply: - Check
correct power supply in test certificate for ampere rating and frequency types.
Check both weather it is overrated or underrated leads to poor efficiency of
motor. If overrated, then it causes burned armature winding due to overheating during high fluctuations of voltage supply.
8)
Costing/ Expenses: - Motor
require maintenance and consumption of electricity so, how much kw of motor you
are using and how much their electricity consumption occur to pay monthly is coming
under costing of motor.
