Question { 53029 }

why does chattering take place in ac contactors?
can it be avoided & what care does the manufacturer take to
eliminate this phenomenon????

Answer

It is mainly because of
voltage drop at
contactor..increase the cable
core size with spare core

Question { Indian Navy, 161066 }

What is the working principle of ceiling fan?

Answer

Ceiling fan is a Single phase Induction
motor. Generally we use a capacitor
start &Run AC Motor for ceiling Fans.
Motor principle: whenever current
carrying conductor is placed in a
magnetic field-it experiences force.
Stator: supplied by 1-phase voltage,
current will produce in the stator
winding-so magnetic field. But AC
motor needs a rotating magnetic
field in
order turn the motor shaft (fan
blades). This is done by applying
voltage with
different phases to different windings.
In a single phase system (like at your
house where you would use a ceiling
fan) there is only one voltage phase.
The capacitor is used to provide a
phase shift (i.e. a time offset between
currents)
in the windings of the motor, making
it
appear that the motor is operating in
a
multiphase system.In Simple Terms, A
single Phase is Split Into Two. There
are
also other methods to split Phase But
using a capacitor is less expensive.
Now we have magnetic field.
We need current carrying conductor:
Because of Induction, voltage will
develop in rotor as It is a closed
circuit
current will produce-so current
carrying conductor placed in
magnetic field.
Rotor will rotate.

Question { Cushman Wakefield, 11643 }

How to protect the water pump by no load running.

Answer

Use a dryrun protection