DOL is Direct on line starter, it is used upto 50 H.P Motors
Star delta starter is Starting time Motor Phases are in Star
and Running time it is convert to Delta scheme.( Because
High H.P Motors are Starting time we are appling Low voltage
by using Star system, and it is increase the Torque.)
DOL MEANS DIRECT ON LINE STARETER WE CAN USE DOL UP TO 110
KW MOTORS SPECIALLY WHERE THE STARTING TOURQUE IS LOW AND
STARTING KICK IS ALSO SMALL. WHILE STAR DELTA IS DESIGN TO
REDUSE THE HIGH STARTING KICK. GENERALLY FANS BLOWER AND
COMPERSSOR MOTORS HAVE HIGH STARTING CURRENT DURING THE
STARTING SO IT IS GOOD TO USE STAR DELTA INSTEAD OF DOL.
ANOTHER DIFFERENCE IS THAT DOL HAS ONLY ONE CONTACTOR WHILE
STARDELTA HAS THREE CONTACTOR.
D.O.L Starter=Direct On Line Starter
1.It does not decrease the starting current.
2.It is cheap.
3.It connects directly the motor with supply for starting
as well as for running.
1.It decrease the starting current to 1/3 times.
2.It is costly.
3.It connects motor first in star at the time of starting
then in delta for running.
I have seen in books that says DOL starters are used up to 50 hp(roughly 37 kw). In my project in singapore, 19 pumps of 160 kw are all start by DOL.(May not start all in one time). It is equal to 214 hp each.
DOL-- As its meaning suggests "DIRECT ON LINE" the motors are provided the direct supply without any changes & this starters are only used for protection purpose (not for soft starting of the motor)and are preffered only upto 10 Hp motors in industries....
STAR DELTA--- are preffered beyond DOL range
first reduced voltage(1/3 of supply V) is given to the motor & as it reaches 70-80% of its rated speed full V is given. (it is the function of changing 4m star to delta)is done to reduce the starting current and to protect the motor.......
for any disagreement mail me at firstname.lastname@example.org
DOL MEANS DIRECT ON LINE STARETER WE CAN USE DOL UP TO 5KW
RATEING IT CONNECTED DIRECT TO THE SUPPLY THROUGH OVER
LOAD RELAY IT DOES NOT REDUSE THE STARTING CURRENT. star
delta are used havy rateing motors because it limits the
starting current in 1/3 tmes of starting current
DOL Starter :
This starter is costwise cheap. it doesnot reduce the
starting current of the motor. The starting current of the
DOL starter is 6 to 7 times of the full load current. We can
use this starter for any higher kW range motors also even
6400kW motor.(In my working place using this DOL starter for
this 6400kW motor.
Note: for any standard cannot mentioned this much of the kW
motors only use in this type of starter nu..
Star/Delta Starter :
This starter is costwise higher. It can reduce the
starting current of the motor. The starter current of the
star/delta starter is 3 to 5 times of the full load current.
Generally in my working place this starter can be use above