Mechanical Shaft Power to Electrical Motor Power

2.2/3.7 ≈ 59% rather than 50% loaded.

If the 2.2 shaft hp already includes a safety factor (?), you might be able to omit the (additional) 1.2 factor. In that case, a standard 2.2kw motor might suffice, especially if it also includes its own service factor. (In the U.S. 1.15 is common, but I don't know about your locale.)

Motors are supposed to be rated by output, with the input power being somewhat higher according to the efficiency of the motor.

thanks for your reply.

location is india. shaft HP is without Safety factor. i think in india Service factor shall not be used.( i am not sure).

We have on CR4 several friends from Tamil Nadu and other areas of India. With luck, some further information may arise that fits your location. There are European motors between 2.2kw (3hp) and 3.7kw (5hp); maybe you can find an intermediate selection that meets IS.

i shall do .

this is the example for choosing motor KW.

like that we are using so many motors in our industry. how we can aviod this problem. once we can select the exact motor with less safety margin.it will create future loads.(unavoidable).

It's ok to use the 3.7 KW motor if that's the next size available on the market, anyway, the load dictates the power consumption and inputs of your motor. If you might select lower rated motor for the use, it heats up more often than the 3.7 KW and when there is heat, it shortens the life of the coils ending to lossing resistance in a short period of time, so you might not be able to serve the capacity its intended.

Try to evaluate with the price, see the difference between 3.7KW and 2.2 KW, it aint that big amount I believe.

It's worth to consider other than buying another 2.2KW at a quarter life span of 3.7KW motor.

Just to clear up one issue though, the motor rated "power" IS the shaft power, not the electrical power (called the "absorbed" power in your part of the world). So a 2.2kW motor will put out 2.2kW of shaft power, but may draw (absorb) 2.75kW of electrical power from the line if it is only 80% eff..

thanks for your information.

the design people keep 15% over margin due to future loads.because if Bucket elevator is design for 100TPH. but client may run 120TPH.in this case motor may not deliver that power.so design people keep some safety margin. so 2.2KW shaft power for 100TPH.if want to run 120TPH. you keep 2.2*1.15.so motor margin is increased.then if critical motor electrical engneer keep some margin that is one size higher frame size.finall motor is over sizied. 100 & 75 % loading motor efficiency is 90.2%.if motor is loading for 50%.the efficiency shall be 89.2only. kindly suggest me

120TPH versus 100TPH is a 20% increase, not 15%. Then 2.2KW x 1.20 = 2.64KW. From the usual local motor sizes, you can select 3.7KW. (Unless, as mentioned before, you can find a European ~3.0KW motor that meet IS.) For these larger motors, you may need to reevaluate the shaft design and increase it.

(There are too many fingers in this pie, by the way.)

You really seem to be concerned that having a motor that is "over-sized" will introduce inefficiencies. Motor ratings define the maximum (nominal) output capacity. An unloaded motor only has to contend with bearing friction and copper losses. Bigger motors have bigger windings and therefore less copper losses compared to equivalent loading onto smaller motors. Bearing friction and cooling fan drag are much the same for either. So having a bigger motor would be more efficient as they run cooler due to lower copper loss. That will let you do your 120TPH easily and not worry about any waste at lower loads. Electric motors have almost no parasitic input energy characteristics unlike internal combustion engines which chew juice even when unloaded. If you think too much you will just confuse yourself.

I'd look at the actual efficiency curves of each motor. You may find that the larger motor and smaller motor have nearly identical consumption at the design load.

It is quite in order to open discussion with (a) motor supplier(s). Telephone?