Thermal model protection for Soft starter

Motor protection is the one of important criteria that we must consider when design the application to avoid serious damage or injury.

Normally we used thermal overload relay to protect electric motor from overload current problem.But if we used soft starter to driven our motor application,the suitable types of protection is using the motor thermal model.

This types provide more precise protection for electric motor and it more accurate and efficient.It only available for high end motor protection relay for conventional starter. read more

Types of soft starter

Soft Starter is the common application for electric motor control driven for industry.It efficient motor control and the application is user friendly.

Soft starter now more advance technologies and can replaced conventional motor starter such as star delta starter,auto transformer or Direct Online starter.It already built in the motor control system and easy to install and wiring to our application.

This time i want share some information about types of soft starter.These types is different because it depend on application and system design.Before we install a new soft starter to our application,we need to understand basic types of soft starter. read more

Star delta motor connection

For star delta stater,the motor connection must have 6 cables from control panel and 6 terminals at induction motor ( U1,U2,V1,V2,W1,W3).To wiring the motor connection for star delta starter,the important thing that we must fully understand is about the basic of STAR DELTA MAGIC TRIANGLE.

For detail about star delta stater please read my last post about it. From this triangle diagram,we can determine the correct phase,cable termination for right terminal and the rotation.As we know,the star delta stater is so tricky if we not fully understand the concept and their method. This time i want share my technique when perform wiring task and connected to the star delta stater for induction motor.

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Star delta starter

This is a starting method that reduces the starting current and starting torque. Star delta starter design normally consists of three contactors, an overload relay and a timer for setting the time in the star-position (starting position).

For the star delta starter, a motor must be in delta connected during a normal run and the main purpose is to be able to use star delta starter.

Star delta starter received the starting current is about 30 % of the starting current during direct on line start and the starting torque is reduced to about 25 % of the torque available at a D.O.L start.

Star delta starter only works when the application is light loaded during the start. If the motor is too heavily loaded, there will not be enough torque to accelerate the motor up to speed before switching over to the delta position. read more

Direct on line starter

Around the world it famous with name DOL starter or direct on line starter.This is the most common starting method available on the market and at basic stater for all motor application.The starting equipment consists of only a main contactor and thermal or electronic overload relay.The disadvantage with DOL starter is that it gives the highest possible starting current.

A normal value is between 6 to 7 times the rated motor current but values of up to 9 or 10 times the rated current exist.Besides then DOL starter draw the starting current there also exists a current peak that can rise up to 14 times the rated current since the motor is not energized from the the first moment when starting. read more

Soft starter

A soft starter has different characteristics to the other starting methods. It has thyristors in the main circuit, and the motor voltage is regulated with a printed circuit board.It can control the current flow to motor more efficient and stability.

The soft starter makes use of the fact that when the motor voltage is low during start, the starting current and starting torque is also low.This type of motor starting is common used for air-condition and chiller system because it can reduce starting current in rush and can made a compressor more life span.

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Electric Motor starter method

Basically motor starter designed for asynchronous motors or induction motor is a mechanism  to start and stop the motor operation.It also provides over current,overload and short circuit protection during operation.

The main task is the starter motor to reduce motor starting currents,High inrush current and prevent the motor from operating when suddenly the power supply to be connected.It is for safety and to avoid serious damage of equipment or person.

Motor starter also capable to controlling the forward reverse rotation, speed motor, braking and various other duties as appropriate.In industry,motor starter very common used to control of equipments and application using electric motor for production or any process. read more

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