This is a starting method that reduces the starting current and starting torque. Star delta starter design normally consists of three contactors, an overload relay and a timer for setting the time in the star-position (starting position).
For the star delta starter, a motor must be in delta connected during a normal run and the main purpose is to be able to use star delta starter.
Star delta starter received the starting current is about 30 % of the starting current during direct on line start and the starting torque is reduced to about 25 % of the torque available at a D.O.L start.
Star delta starter only works when the application is light loaded during the start. If the motor is too heavily loaded, there will not be enough torque to accelerate the motor up to speed before switching over to the delta position.
Description of Star Delta Starter Operation
For star delta starter,the basic function is to enable the motor to start and the motor windings are configured in a star formation to the supply voltage.
The voltage applied for star delta starter to the individual motor winding is therefore reduced by a factor of 1√3 = 0.58 this connection amounts to approximately 30% of the delta values. The starting current is reduced to one third of the direct starting current.
Due to the reduced starting torque, the star-delta-connection is suitable for drives with a high inertia mass but a resistance torque which is low or only increases with increased speed. It is preferably used for applications where the drive is only put under a load after run-up.
After motor run-up, in most cases an automatic timing relay controls the switch-over from star to delta. The run-up using star connection should last until the motor has reached the approximate operational speed.
so that after switching to delta, as little post acceleration as possible is required. Post-acceleration in delta connection will instigate high currents as seen with direct on-line starting.
The duration of start in star connection depends on the motor load. During delta connection, the full mains voltage is applied to the motor windings.
To enable a switch-over from star to delta, the six ends of the motor winding are connected onto terminals. The contactors of a star-delta starter switch over the windings accordingly.
How star delta starter works?
Starting in star, the main contactor connects the mains to winding endings U1, V1, W1.The star contactor shorts winding endings U2, V2, W2.
After successful run-up, the star contactor switches itself off and the delta contactor connects terminals U1/V2, V1/W2,W1/U2.
When changing from star to delta, we should pay attention to ensure it running in the correct phase sequence.Incorrect phase sequence can lead to very high current peaks during the cold switch-over pause, due to the easy torque reduction following re-start.
High peaks current can damage the motor windings and stress the control gear unnecessarily. The rotation of the motor has to be considered as well.If wrong rotation,we should change the rotation by switch the phase.I discuss detail about How to change star delta starter motor rotation in my separate post.
For star delta starter circuit diagram,wiring technique and motor base termination,Please read my post for star delta motor connection.Also for simple star delta control circuit wiring and types of star delta starter,please refer to my post for Electro mechanical star delta.
For more detail,please refer to ELECTRIC MOTOR HANDBOOK :-
Good informations in this site. how to to find out the wrong termination in star delta connection. for example in star delta connected motor star in star mode but after change in delta mode contactor of delta and main are in pick up condition but motor got off not in trip. can u explain this
Are u already confirm your motor connection true or not?i think your motor terminal connection maybe wrong..please refer my last post about star delta motor connection
For this ,, the W1,V1,U1 are connected to the same phase of W2,V2 And U2. So you need to change the cable that link the W2,V2 and u2.
please give a diagram of star-delta starter with transition resistors(Kondorfer)
please refer to my post : http://www.electricneutron.com/motor-control/electro-mechanical-star-delta-starter/
hi,
The artical which is above is more enough to understand and knowledge of particular thing.
very usefull
plz send to my email a control circuit of forward reverse connection…A.S.A.P….thank you…
i will discuss in my next post about control circuit of forward reverse for star delta starter…thanks
can anyone tell me about the difference in delta and star connections from the generator?
please post me the book to my email,thank you.
dfghsdhr
in a star delta stater how we can set the timer timing to switch to delta from star according to load characterstics.
it hard to setting the best timing for star delta starter.Typical setting for timer is around 8 until 10 second….
Dear Sir,
We are manufacturer of animal food.it is in pallate fome.and our requirement of Star-Delta Starter for 40HP Motor.so,please give the Quotation for the same.
Kind Regards,
Chandrakant Parekh.
+91 95588 13099
Director
Divine Ani-Food Manufacturing Unit.
Unjha(Mehsana)
Dear Sir
please tell me ,
what will happen if the motor is running and contactornya only 1 ( Delta contactor off )
regards
HF
Hi I am looking for a way to change the rotaion on only delta as motor runs forward in star but tries to reverse rotaion when changing into delta causing fuses to blow.tried to change L1 L3 at motor but motor runs at very high amps
Dear Sir,
Please read my last post : http://www.electricneutron.com/motor-control/how-to-change-rotation-for-star-delta-starter/
Dol starter pump connection
Hi, Can u plis give me control circuit for the compressor of star delta with addition of the solinoid valve and pressure switch
we have supplied dol starter of 10hp motor but it fails because of relay got burnt & after that we once again replaced the relay/contactor it works for 03 days same has repeated & motor winding got burnt.
then we replace the star delta starter found the same has been repeated after 02 days of working condition
kindly inform us the reason for the above if any suggestions.
suresh k g
Please check your actual full load and motor sizing
Please check current rating for your contactor.It should same or high ampere rating from your motor full load ampere.
motor in starting come in star connection then after delta. motor burn reason is single phasing check the both contactor continuity that incoming band outgoing connection voltage are ok or not and also check the timer working and thing is o/l relay burn there are three reason
1) bimatlick strip dusty
2) lose connection
3)lower rating
best information
I need for star Dalta with timer gigram
Sir.. can u kindly help me out as i am confused while connecting my 40hp motor crampton greaves with the starter. Here i will give u the sequences..
Starter.. C1 L1 A1 L2 B1 L3
AO BO CO
Motor… U1 (u ) W2 (k)
V1 (v) U2 (l)
W1 (w) V2 (m)
SO kindly help give me the direction.. waiting for ur anticipation.
How to set a overload relay setting in star as well as in detla connection ??
Very useful
Thanks for your information. Please am a new beginer. Can you please send me a book that contains everything about motor staters method. Again I want to know how the. Star contactor is being connected to the three phase machine. Thanks for your anticipated effort
Sir,
I have a Centrifugal Fan of 150 HP motor which we run with star delta starter with timer and thermal relay base contactors. How much time can be set between star and delta starter ? any thumb rule which depends upon motor HP or any ??
When we are starting the motor it draws 340 amp. it reduce gradually up to 285 amp. and then come in delta in 25 sec. In delta it draws 825 amp. and reduce to 70 amp. with in 2 sec. and again after 2 sec. motor trip. What will be the reason ?? Please help me.
What’s star and delta sent me in email
please my rquest send the one video hindi mediem please star delta motor control with conection
hindi longuage send star delta motor control conection
please say
Me how do select 3 magnetic contractor and over load on star delta operation 75 hp motor . please gave me calculation
v=440
p.f=0.8
3 phase
75 hp
sir place say
Me how do the select star delta magnetic connector and over load. please gave me calculation
v=440
pf=0.8
75hp motor (please send my email addresses)
sir please help me mai star Delta starters se ek starters se do motor ko on off karna hai please give me diagram
why relay burns again and again i have 30hp motor on tubewell .can it burn because of nutrul from transformer is weak.i use jyoti star delta starter
I have a motor connected in Delta but two times now it has been making contacts get jammed in whenever there is a phase failure ie when one phase goes off.This happens before the over load relay trips yet the over load is set at the minimum.Motor full load is 58A/40hp.The supply is direct on line.What do you think is the cause of this.Can the star connection solve the problem.
Good post . I Appreciate the facts , Does anyone know where my assistant can get a blank IRS W-2 form to fill out ?
hello sir,
my name is murali I need to to know how to identify star delta timer failure.
Hi i have a granulator connected in star delta. The second contactor keeps on blowing. What could the cause of this be?
Please check your Ampere rating for your contactor vs your Full Load Ampere
75 HP/55k/92 amp- star delta starter for 55 HP motor
HELLO
PLEASE QUOTE
STAR4-DELTA AHU
MOTOR STARTER (SET6)
FOR:
2 SETS 25HP
2 SET6S 15HP
2 SETS 10HP
LOOKING FORWARD TO HEARING YOU SOON.
B/R
ROLLY/MANILOA OVERSEAS INC. TEL;6328004227 FAX;6328004172
please say
Me how do select 3 magnetic contractor and over load on star delta operation 75 hp motor . please gave me calculation
v=440
p.f=0.8
3 phase
75 hp