What is a DOL Starter?
Direct on-line is the simplest form of motor starter. This method involves directly switching the polyphase stator onto the supply mains. This is also called an “across-the-line starter.” Depending upon size and design, the motor takes a low-power factor starting current of 5 to 7 times its full-load current. Such large currents of short duration don’t harm the rugged squirrel cage motor, but the high currents may cause objectionable voltage drops in the power supply lines feeding the induction.
These large voltage drops cause undesirable dips in the supply line voltage; consequently, the operation of other equipment connected to the same supply line is affected considerably. A common example is the momentary dimming of lamps and tube lights in the home when a refrigerator motor starts. In the direct-on-line method of starting cage motors, the motor is connected using a starter across the full supply voltage.
This consist of the overload relay , protecting device and main contactor- these all are used for the motor starting operations in which the stator winding are directly connected to the main supply.
DOL Starter
For cases to avoid damage to the motor, various techniques are used to reduce the starting current with the use of a motor starter, these techniques vary on different factors and also protect the motor from overcurrent and overloading. DOL starter is one of the techniques used and in this article, we are going to discuss DOL starters and the starting of induction motors. We will cover what is starting induction motors and their functions, what are DOL starters, their application, terminologies, theory, construction, working, and the difference between DOL and star-delta starters.
Table of Content
- DOL Starter
- Important Terminologies
- Construction and Working
- 3 Phase Motor Starter with Overload Protection
- DOL Starter Wiring Diagram
- Advantages , Disadvantages and Applications