In this method, full voltage is applied to the motor, but the starting current would be very high(usually 5-8 times more than it’s rated current). 1) DOL StarterĭOL stands for Direct Online Starter, most commonly used in the industry to start the motor. There are many types of starter used to start the motor, in this blog we are going to see some basic motor starters and their conversion in PLC ladder logic. The motor starter provides other functionality also to protect the motor from any other fault like overload, single phasing, under-voltage, voltage unbalance, stall protection. As the motor accelerates to its running speed, full voltage is applied to the motor. But for a heavy motor with more power, other advanced starters like Star-Delta, Soft Starter, and VFD Starter is used.Īdvanced starter(like Star-Delta, Soft Starter, VFD Starter) applies less voltage to reduce the high initial current, this voltage reduction is for a short time. Normally DOL(Direct On-Line) starter is used to start the motor.
The Motor Starter is a device that is used to start and stop the motor to which it is connected. Therefore, Starter is needed to limit the starting current to avoid damage to the motor as well as other connected electrical equipment in the same line supply. It also generates a voltage dip on the supply line which might result in the malfunction of other connected electrical equipment. This huge current can damage the motor windings. This current reduces as the motor achieves it’s running speed. Initially, it will take a huge amount(normally 5-8 times more than it’s rated) current. So, In this blog, we are going to see the What is Motor Starter, Types of Starter and Why do we need starters to start any motor?Īdditional to this we will also cover the basic conversion of this motor starter into PLC Programming using Ladder Logic.Īs we all know that when we supplied a 3-phase supply for the starting of induction motor. To drive this Electric Motor, we need Motor Starter. If you want to drive any mechanical equipment then you have to connect it with Electric Motor.
This means that if the coil that drives the motor in the forward direction is energized, a normally closed set of contacts wired in series with the reverse coils will prevent that coil from being energized as long as the forward coil remains energized.In Electrical Engineering, the most basic topic is Electrical Motor.
To prevent unintentional energization of both the forward and reverse coil at the same time, the coils are equipped with normally closed contacts, which are then wired in series with the opposite direction’s coil to act as an electrical interlock. Reversal of three-phase motor rotationīoth coils power contacts feed through a single set of OLR to provide running protection in both directions. When the alternate coil is energized, Lines 1 and 3 are interchanged with Terminals 1 and 3, allowing for a phase shift in the 3-phase circuit, driving the motor and causing it to rotate in the opposite direction. They are connected so that under normal conditions, one coil will connect L1 with T1, L2 with T2, and 元 with T3. Motor Starters and Contactors 15 Forward/Reverse Starters NEMA Forward Reverse motor starter with OLRĪ forward/reverse magnetic motor starter is constructed from two regular contactors installed with a mechanical interlock that prevents both coils from pulling in simultaneously.