In star connection motor is taking low current and produce
high torque and in delta connection motor is taking high
current and low torque.to start the motor from stand still
condition we requeired high torque so first motor should in
star connection and then it should have conti. with delta
A star connected motor takes less current compared to a
delta connected motor since the phase current is 1/sqrt3
times the line current, but torque developed by the motor is
affected, since starting current is heavy in order to reduce
the heavy inrush current we place a star delta
starter.....so tat starting current can be comparitively
small...the reason for shifting to delta connection(after
motor attains 80% of the rated speed)is the power output of
the motor wil be 3 times the output wen it is connected in
star.....it doesn;t mean tat the m/c 3 times more efficient
than star connected one..but correspondingly the power drawn
by the motor also increases.........
comments r welcome....
actually we uses star and delta connections in a motor for
starting purposes,when the motor starts it will take high
current which effect to our power factor so to reduce the
inrush current we use the star/delta connections. in start
we get high tarque and less current which is our
requirments,in delta we get high current and less torque.
how to find 5 kilo meter long under ground 33 kv cable
fault location if IR VALUE shows 0.05 M ohm @5000 volt.and
cable fault locator shows some time fault distance 3 kilo
meter ,3.7 kilo meter and some time 1 kilo meter? now how
to find the fault location that where is leakage.
In 110V DC supply,if a closed circuit gets open, How can we
identify the voltage which is measured after the
resistor(4KOhm) which is open with negative.it shows 55V +ve
when measured, also the actual positive source is 55V +ve
.Because there is no voltage drop in open circuit. How can
we identify whether this is the voltage which is series with
the resistor or the DC source direct +ve.