Why, the starting current of 3 phase Induction Motor is 7
to 8 times its rated current?
Answers were Sorted based on User's Feedback
Answer / roysayan01
From the equivalent circuit of an induction motor it can be
seen that the the expression of current is
I=E/[(jX1+R1)+(jX2+R2/s)
Generally during running condition slip,s=0.03
i.e the value of slip is very low which increases the
resistance (R2/s) in the above eqn and as a result of which
current decreases
but
at starting s=1 and so the resistance (R2/s) is small and
the current is 7 to 8 times higher than the current during
running condition.
Hope i explained it vividly.
For ny doubt or query feel free to mail me at
roysayan01@gmail.com
| Is This Answer Correct ? | 46 Yes | 2 No |
Answer / esha
The starting current, sometimes called inrush current will be 8-10 times higher than the motor's rated current because the motor is at rest.
When at rest, the motor appears to be a transformer, with it's secondary winding short circuited, i.e. the rotor winding or squirrel cage is a closed circuit. This results in a low impedance to the system voltage and the motor has a "locked rotor" current of typically 6 times full load current, but also up to 8 and sometimes 10 times current.
This starting value is independent of any load attached, however, the inertia of the motor and load has to be overcome. This is especially true when the motor is connected to a load, like a conveyor belt with product on it. The larger the inertia, the longer the motor takes to reach full speed.
As the motor accelerates, part of the starting current power overcomes this inertia and is conveted to kinetic energy.
info from-wikianswer.com
| Is This Answer Correct ? | 13 Yes | 3 No |
Answer / vinay singh
the air gap path provide more reluctance path to the mutual
flux but mutual flux is constant due to constant applied
voltage. so for constant mutual flux the magnetising m.m.f.
is more and stator draws more magnetising current during
starting.
| Is This Answer Correct ? | 5 Yes | 3 No |
Answer / sdkarwa
because end rings of the squirell cage induction motor are
shorted
| Is This Answer Correct ? | 6 Yes | 8 No |
Answer / s.eltarhoni
i confirm that the obove two answers are right and the
second is more detailed but i would like you to answer why
this case appeares only at starting
| Is This Answer Correct ? | 1 Yes | 3 No |
Answer / richard
during starting time there wont be back emf so it takes 7
to 8 times high current
| Is This Answer Correct ? | 6 Yes | 8 No |
Answer / stalin raj
The motor needs high torque to starts its rotation.The
torque is directly proportional to the square of the
current.Hence it takes a large current at starting.
| Is This Answer Correct ? | 7 Yes | 9 No |
Answer / mukhesh
because end rings of the squirell cage induction motor are
shorted so resistance is small it offers that much of
currentt here is no windings but in slip to improve the st
torques windings are present it offers low current than sqirrel
| Is This Answer Correct ? | 3 Yes | 7 No |
What are the safety equipments you should use while you are in a hvac switch yard
1 Answers GPSC Gujarat Public Service Commission,
testing of Vector Group – YNaoD II
How can I model an open-delta ground transformer for a network supplied by 4 unit GTG and power transformer in ETAP?
what is difference between MCB & MCCB
Why MCCB is Getting tripped sometimes when there is no load in the Midnight ?
What's the difference between a generator using 50Hz and 60Hz? When do we need to use a generator 50Hz and 60Hz?
How can calculat the lode of transformer?
In 11KV Double pole structure for each phase we are using Disc one Insulator. Why we are not using 2 r above insulators instead of one insulator?
WHAT IS THE DIFFERENCE BETWEEN AN ACB & mccb 7 WHAT IS THE CRITERIA WHEN TO USE WHICH OF THE TWO
1. which type of transformer connection is preferred in case of power supply transformers? (A) Star/Star (B) Delta/Delta (C) Star/Delta (D) Zig Zag/Star 2. In a power transformer usuall which winding is closer to the core? (A) Primary winding (B) Secondary winding (C) Low Voltage winding (D) High Voltage winding 3. The power factor of a purely inductive load is (A) Zero (B) Lagging (C) Leading (D) Unity.
9 Answers CECRI_Central_Electrical_Research_Institute,
Why in India distribution transformer are connected in Dyn11 when we know capacity of v-v connection can be increased by adding only a single transformer?
circuit diagram of trip circuit supervision relay
Civil Engineering (5086)
Mechanical Engineering (4456)
Electrical Engineering (16639)
Electronics Communications (3918)
Chemical Engineering (1095)
Aeronautical Engineering (239)
Bio Engineering (96)
Metallurgy (361)
Industrial Engineering (259)
Instrumentation (3014)
Automobile Engineering (332)
Mechatronics Engineering (97)
Marine Engineering (124)
Power Plant Engineering (172)
Textile Engineering (575)
Production Engineering (25)
Satellite Systems Engineering (106)
Engineering AllOther (1379)