DOI stands for direct online stater is a method of starting a 3 phase induction motor. In DOL an induction motor is connected directly across its 3 phase supply and the DQL stater applies the full line voltage to motor terminals.
Advantages of DOL starter:
- It is a simple and most economical starter
- Easy to understand and troubleshoot
- It is easy to operate
- DOL starter connects the supply to the delta winding of the motor device
- Provides nearly full starting torque at the starting
- More comfortable to design, operate, and control
- DOI is an inexpensive starter
- The designing, operating, and controlling of this starter is very easy
Disadvantages of DOL starter:
- Mechanically tough
- Unnecessary high starting torque
- DOL starter reduces the lifespan of the machine
- High starting current
- DOL start causes a significant dip in voltage, hence suitable only for small motors
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