Answer / irfan

3 phase indution need rotor resistance starter,dol starter
etc. because to reduse heavy starting current and provide
overload and novoltage protection

Answer / sudipta

Starter is connected in series with the armature. Now, this
armature current is given by Ia=(v-Eb)/Ra. Here, v is
terminal voltage, Eb is back emf, Ra is armature resistance.
In the case of an induction motor,at the time of
starting,back emf is zero. So, Ia=v/Ra. As Ra is very small,
Ia is too high. So,a resistance(R) is connected in series
with the armature. So, the starting current decreases and
motor gets protection from overcurrent.

Answer / balakrishna shetty

When 3phase induction motor is directly connected to the supply, it takes heavy current at starting ( 5 to 7 Times the full load current ) and creates a large voltage drop in the line.Due to this
(a). Motor winding May be damaged.
(b) Neighbouring consumers are inconvenienced.
To avoid this starters are used.

what parameters should we check to reduce the power bill

0 Answers  

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How many types of interlocking use in screw type air compressor,make-Kaser(BSD MODEL)?

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HOW MANY POLES ARE THERE IN 3 SLOTS PER POLE PER PHASE MOTOR

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If single phase voltage level is 230V than why three phase voltage level is not 660V ?, but it is only 440V.

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RATING OF LIGHTENING ARRESTER FOR 11 KV LINE IS 9 KV BUT WE KNOW THAT LIGHTENING ARRESTER IS USED FOR OVER VOLTAGE PROTECTION SO WHY NOT THE RATING OF LIGHTENING ARRESTER BE MORE THAN 11KV ???????????????//

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what is leading and laging please in details

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ro plant grundfos bm30type pump.we start the pump using siemens 3rw 4423-1bc44, 30kw soft starter. bur its failier frequently. so we planed to change the dol starter. sp please tell me any budy its possible or not翿შ†

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What will happened, if field voltage change with 220 voltage to 110 voltage for a dc shunt motor?

1 Answers  

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