Equipment drives selection gear and motor.

Dear All

For the selection of the drives for belt conveyors, Bucket elevators, drag chains etc I used following formula, calculate the absorbed power and add 50% for the gear and 20% for the motor and select gear and motor from the catalogues, i.e. absorbed power 100Kw, gear power 150Kw, motor power 120Kw. My colleagues say I am exorbitant with my percent but I say we select a drive to operate for 20-25 years.

What is your proposal, shall we stay as above or change the philosophy and at what percent.

Thank you in advance.

Apostolos.