Sponsored Results

Navigation

Random Photo

Forum Threads

...

Star delta starter with control circuit drawing.

The Star/Delta starter is manufactured from three contactors, a timer and a thermal overload.The main contactor connects the reference source voltage L1, L2, L3 to the primary terminal of the motor U1, V1, and W1.

star delta starter


Below is a schematic of star delta starter.

star delta starter control wiring


When the start button is pressed, main contactor coil K1 is energised as well as star contactor coil K2 via normally closed contact K3 (delta contactor) and timer contact T.
Timer is most commonly fitted to K1 and will normally operate a few seconds (typically 5-30 seconds) after K1 has energised. The Star and Delta contactors are electrically interlocked and preferably mechanically interlocked as well. This prevent booth contactors to be energized at the same time.

After time set on timer T the timer’s auxiliary contacts in star coil circuit will open  (at the same time auxiliary contact in delta coil circuit will close) and current then flows through the normally closed star contact K2 to operate the delta coil K3. Now Motor terminal connection change from star to delta connection.

 Things you need to remember about star delta starter
  • It requires an induction motor with six winding ends brought out of its terminal box.
  • It requires 2 set of cables from starter to motor.
  • The supply voltage per phase in star is only 58% of the value which would be applied if the windings were connected in delta and this reduces the starting torque and starting current to 1/3.
  • The contactors are smaller than the single contactor used in a Direct on Line starter as they are controlling winding currents only. Contactor K3 can be AC3 rated at one third (33%) of the motor rating. Contactors K1 and K2 are AC3 rated at 58% of the current rating of the motor.


See also:

 


Recommended :




Megger MFT1720 17th Edition Multifunction Tester MARTINDALE ELECTRIC - SB13 - SOCKET ADAPTOR MEGGER MIT320-EN  FLUKE T5-1000, FOR VOLTAGE AND CURRENT ELECTRICAL TESTING


Ratings

Rating is available to Members only.

Please login or register to vote.

No Ratings have been Posted.
Render time: 0.11 seconds
2,532,576 unique visits