3 phase DOL Starter Motor Diagram

What is DOL Starter

A DOL starter (or Direct On Line starter or across the road starter) could be a technique of popping out a three-section induction motor. In DOL Starter associate induction motor is connected directly across its 3-phase offer, and also the DOL starter applies the total line voltage to the motor terminals. Despite this direct association, no hurt is finished to the motor. A DOL motor starter contains protection devices, and in some cases, condition watching. A schematic drawing of a DOL starter is shown below:
Since the DOL starter connects the motor on to the most path, the motor attracts an awfully high inflow current compared to the total load current of the motor (up to 5-8 times higher). the worth of this massive current decreases because the motor reaches its rated speed.

DOL Starter Wiring Diagram

The schematic for a DOL stater is shown below. an immediate on-line starter consists of 2 buttons, a inexperienced button for beginning and a RED for stopping purpose of the motor. The DOL starter contains associate MCCB OR gate breaker, contactor associated an overload relay for cover. These 2 buttons, i.e. inexperienced and Red or begin and stop buttons management the contacts.

To start the motor, we have a tendency to shut the contact by pushing the inexperienced Button, and also the full line voltage seems to the motor. A contractor is of three poles or 4-poles. If any fault happens, the auxiliary coil gets de-energized, and thus the starter disconnects the motor from offer mains.

3 Phase Motor Starter with Overload Protection

When a motor attracts excessive current to fulfill the load needs such this load demand goes on the far side the rated limit, this can be called overload. Thermal overload protection may be a style of security once the motor attracts over current or excessive current and causes heating of the instrumentality. Overload is additionally the kind of over current. therefore overload relays are utilized to limit the quantity of current drawn.

But that doesn’t mean that protects the tangency. Fuse or MCB employed in the system protects the over current. Overload protection opens a circuit at comparatively low currents that are a touch on top of the rating of the motor. Overload currents are doubtless to break if they persist for a protracted time, i.e. it’ll not trip if a high price of current flows for a brief amount like the beginning of the motor.

we regularly offer overload protection via associate overload relay. Overload relays additionally be|is also} solid-state devices with adjustable trip setting also referred to as because the electronic relay or by interacting with connected temperature sensors referred to as as a thermal relay or if solely operates for excess current flow then referred to as as a magnetic relay. for many motors, the utmost rating of the overload protection device is one hundred and twenty-fifth of the complete load ampere rating.

DOL Starter Wiring Diagram

The schematic for a DOL stater is shown below. an immediate on-line starter consists of 2 buttons, a inexperienced button for beginning and a RED for stopping purpose of the motor. The DOL starter contains associate MCCB OR gate breaker, contactor associated an overload relay for cover. These 2 buttons, i.e. inexperienced and Red or begin and stop buttons management the contacts.

Advantages of DOL Starter

The advantages of a DOL starter include:

1. Simple and most economical starter.
2. More comfortable to design, operate and control.
3. Provides nearly full starting torque at starting.
4. Easy to understand and troubleshoot.
5. DOL starter connects the supply to the delta winding of the motor.