30 KW MOTOR NOMALLY FULL LOAD 54 AMPS, BUT WITH OUT LOAD
30% CURRENT WILL TAKE,ANY THREE PHASE INDUCTION MOTOR WITH
OUT LOAD 30PERSENT CURRENT WILL TAKE.

No load current of a 3phase induction motor varies
according to its KW and rpm. Normally as a thumb rule
fraction HP motors (below 2.2KW) will be 50% of full load
current. Above 2.2KW may be 20% to 30% OF full load
current.

no standerd farmulla to calculate the noload current but as
a thumbrule 3 ph induction motor will draw 30% current on
no load but few motor will take 50 to 60 % current

Actually,there is no standard formula to calculate the
noload current of the motor.Normally 25% to 40% of full
load current of the motor.Also depending upon motor KW and
supplier..

There is no standerd formula for calculating no load
current, It depend on the desine and material used in
motor. There is a major role of material(winding wire&
stamoing)to anhancing the efficiancy of motor.

Torque of a rotor depends on its diameter and weight along
with winding as well as material and methodology of
construction and also on applied bearings and lubrication. A
bulky, heavier rotor will draw more no load current than
small, light weight rotor. Formula : Torque (T) = qr (Where
q=Tangential force acting at PCD of winding due to effect of
current flowing through it, and r= distance of winding from
centre of the shaft). This torque only tries to rotate the
dead weight(W) of the rotor on no load. It can be said
T=qr=(W + rolling friction in bearings + wind resistance).
These all factors can be calculated easily and then finally
to arrive the result i.e. no load current, however bearing
frictional force and wind force can be ignored.