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Why Is The Starting Current High In A Dc Motor (or) Why Do We Use A Starter? |
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Answer» For DC MOTORS, Voltage equation is V=Eb-IaRa Where V = Terminal voltage, Eb = Back emf in Motor Ia = Armature current Ra = Aramture resistance. At STARTING, Eb is zero. Therefore, V=IaRa, Ia = V/Ra, where Ra is very LESS like 0.01ohm.i.e, Ia will become enormously increased. The EXCESSIVE current will damage commutator and brushes and eventually BLOW out the fuses. For DC motors, Voltage equation is V=Eb-IaRa Where V = Terminal voltage, Eb = Back emf in Motor Ia = Armature current Ra = Aramture resistance. At starting, Eb is zero. Therefore, V=IaRa, Ia = V/Ra, where Ra is very less like 0.01ohm.i.e, Ia will become enormously increased. The excessive current will damage commutator and brushes and eventually blow out the fuses. |
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