Answer / p.raju

Starting condition

when the field wdg is open means there is no production of
magnetic field,even though the armature carries the current
(limitted by starter) there is no motoring action thats why
motor will not start.

Running condition

sudennly the field disappears thats why motor attains a
very high speed....

Answer / rvg

AT the time of starting:

since the winding not energized, there will not be magnetic
field and at the same time armature being energized. so the
effect is ,a low resistance path being energized, so there
are chances of armature winding damage.

During running condition:

As soon as the field winding got de-energizes, the magnetic
field becomes close to zero(practically there will be some
residual magnetism), and speed of the motor will be much
higher and ultimately, the rotor will will be
damaged(mechanical parts).

Answer / diptendu gantait

WHEN THE MOTOR FIELD OPEN THEN ARMATURE IS BURN-OUT OR
ROTOR GATE MAX SPEED AND MAY BE THROWNOUT BY THE DANGEROUS
SPEED.

Answer / dharma

when starting condition no flux in the filed because of
opencircuit. when open motor run the motor goes to
dengirous high speed and burn.

Is C.T will sense the current in both direction. As i know the C.T will sense the current in only one direction.

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