There are following formula's which are very useful for an electrical engineer while doing calculation on various aspects for induction motors.
High Inertia Loads
High Inertia Loads
t =

WK^{2}
x rpm
308 x Tav. 
WK^{2} = inertia in lb.ft.^{2}
t = accelerating time in sec. T = Av. accelerating torque lb.ft.. 

T =

WK^{2}
x rpm
308 x t 
For calculating time required to accelerate an induction motor at a particular load formulaI will help the same
If you know want a particular motor to get accelerated at a given time then required torque can be calculated by using formulaII in above.
Both formulas are quite helpful while doing programming in Variable frequency drives and softstarters.
Inertia
reflected to motor = Load Inertia X (

Load rpm/Motor rpm

)X(Load rpm/Motor rpm)

Synchronous Speed, Frequency And Number Of Poles Of AC Motors
n_{s}
=

120 x f
P 
f =

P x n_{s}
120 
P =

120 x f
n_{s} 
Relation Between Horsepower, Torque, And Speed
HP =

T x n
5250 
T =

5250 HP
n 
n =

5250 HP
T 
Motor Slip
% Slip =

n_{s}
 n
n_{s} 
x 100

Symbols
I

=

current in amperes

HP

=

output power in horsepower

n

=

motor speed in revolutions per minute (RPM)

ns

=

synchronous speed in revolutions per minute (RPM)

P

=

number of poles

f

=

frequency in cycles per second (CPS)

T

=

torque in poundfeet

EFF

=

efficiency as a decimal

PF

=

power factor as a decimal
