star delta transition starter


Thread Starter


Dear all,
Is it necessary to make the transition contactor (transition resistor) close when the motor is running at star status, or otherwise only necessary to close during the changing moment to delta status?
Moreover, how to size teh transition resistor?
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Star Delta starters - turn on the line and star contactors. After time turn off the star contactor and approx 80ms later turn on the delta contactor. Make sure you use software interlocks and, preferably, electrical and mechanical interlocks.
This is very basic electrical stuff that we all learn as apprentices and if you do not know what you are doing you should give the job to someone who does, or go to college and learn. If the star and delat come together there is an extremly large explosion. The higher the fault level, the larger the explosion.
Dear Friend,

When you fix mechanical interlock, electrical lock and timer delay it is not necessary
during PLC programming to keep some ms slape between the contacts as well as interlock in programming too.

Sanjay Vani
For the information and much more
You can get the free klockner moeller "Automation and power distribution wiring manual" which covers all types of star delta starters.

The size of transition resistor is:
In Motor = Power Motor (KW)/Voltage Motor x 1.732 x Cos phi Motor
R = Voltage Motor/1.732 x In Motor

Supriyatna, Tangerang-Indonesia
[email protected]
Responding to Anonymous' original query:

For the first part... Yes, the resistors used for the closed-transition starter are initially connected in parallel with the windings.

For the second part, sizing, a greater issue must be addressed! The very fact that you are considering a closed-transition circuit is indicative of the motor's inadequacy for the application. That is, the accelerating torque is too great, the driven machine inertia too large, or both.

Phil Corso, PE
Boca Raton, FL
[[email protected]] ([email protected]) {[email protected]}
The installation for Star delta close transition is:
Step one: The motor running at star connection.
Step two: The motor running at star parallel with resistor at the winding motor less 50ms.
Step three: The motor running at delta serial with resistor at the winding motor less 50ms.
Step four: the motor running at delta connection.

Supriyatna, Jkt-Ind
[email protected]

Thulani Blaai

Hi there I'm only a first year Apprentice so I need all the info I can get please send me the manual ASAP if that's possible.I would gladly appreciate your help.
Pls, can u kindly give me details on the materials required to build a Star-delta Transition starter.

Also, what r d advantages over the Regular starting method.