Answer / krish

When a motor starting with star/Delta starter,In case of
Open transition during change over time from Star to Delta
for momentarily the supply will interupted for the motor &
it changes to Delta,But in case of closed Transition there
connect resistance will when change form star to delta &
this arrangement will avoid the open Interuption

Answer / sashi kanth

COnsider a 3 phase induction motor is switched on by the
means of starter in delta configuration winding of stator.
This is usually done to reduce the time the machine takes
to run at rated speed as the voltage across each phase is
not V/1.732 = 230 V but is 415 V. During normal operation,
winding has to be converted to star configuration. This
transition can be done either by disconnecting the prior
configuration for some instant of time and connecting the
other configuration. As the machine is disconnected from
the excitation for some instant of time it is called open
transition. Closed transition of stator configurations is
done without losing the continuity of the excitation.
Refer to Control of electric drives by Bhattacharya and it
will be more clear.

Answer / dave

worked for carrier a/c 35 years. in a standard open
trastion when charging from star to delta the motor
effectively slows momenatrily for a 1/5 of a scond. closed
traansition this does not happen ,the change from star to
delta is less noticeable.closed transiontion has a fourth
contactor and resistor bank to prevent that 1/5 of second
power loss to the windings .I need some wiring digrams of
closed transion staters to show the tecs how this works

Answer / bala123

can any body please tell about the calculation for find
this resistance values??????????????????????????

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