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Question
how we calculate the 30 KW 3phase electric motor current on 
noload
 Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
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.
 
Is This Answer Correct ?    155 Yes 36 No
J.kesavan
 
Answer
# 2
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.
 
Is This Answer Correct ?    62 Yes 16 No
D.g.skandan
 
 
 
Answer
# 3
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
 
Is This Answer Correct ?    44 Yes 9 No
Suresh
 
Answer
# 4
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..
 
Is This Answer Correct ?    39 Yes 4 No
Suthan Prabhu
 
Answer
# 5
In=p/1.732*v*p.f

=30x1000/1.732*.8*380

=57A

Ino=57/3
19A
 
Is This Answer Correct ?    53 Yes 28 No
Mahmoud
 
Answer
# 6
practically the no load current of 3 phase motor varies
from 25% to 35% whereas in 1phase it is nera to full laod.
 
Is This Answer Correct ?    21 Yes 14 No
Surajkant
 
Answer
# 7
I agree with suthan prabu. there is no formula to calculate.
depends on the manufacturers design, but full load curret can be calculated.
 
Is This Answer Correct ?    17 Yes 10 No
Pillay
 
Answer
# 8
3 ph induction motor will run 30% current on
no load but few motor will take 40% current


EXAMPLE:

KW=3.7KW,Amps=7.45,(Assume 40% Of No Load Amps)

No Load Amps = 7.45*0.4
= 2.98A
 
Is This Answer Correct ?    7 Yes 0 No
K.arivazhagan
 
Answer
# 9
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.
 
Is This Answer Correct ?    7 Yes 1 No
S.p.singh
 
Answer
# 10
Equation with power factor in is the most correct. Several
issues shall be counted before estimating no load current :

- number of the poles

- power factor - there is a curve from the manufacturer
showing how this is changed in a function of power

- size of the machine

- speed

- way of feeding machine - DOL / inverter

Example :

500kW machine 690V 750rpm In=670A, No load - 285A (~42%)

500kW machine 690V 100rpm In=520A, No load - 180A (~34%)

Answer :

KW = 1.732 * V * I * cos phi * K

where K is a factor taking all other circumstances (0,7 to 1
where 1 is ideal situation) lower K for higher number of
poles, multispeed machines, specific construction etc...
 
Is This Answer Correct ?    2 Yes 2 No
Marcin
 

 
 
 
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