Overload relay setting and calculation

22/04/2011 by 90 Comments

Overload relay is the one of important device for motor control.It can prevent our motor from overheat or winding burning due overload of ampere.

We need to setting the value of overload relay properly depend on our application and motor full load ampere.If we setting low from FLA,it can cause motor trip c0ntinues and process not running smoothly.

But if we setting to high from FLA,the overload relay cannot protect the motor if overload happen.It can cause the motor failure or winding burns.So we must calculated and get a right setting for the overload relay. read more

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Types of motor overload relay

21/04/2011 by 8 Comments

A motor overload relay is an electro-mechanical relay that is operated by heat developed in the relay.When the level of current in a circuit reaches a preset value, the increased temperature opens a set of contacts.

Overload relay should install in our motor starter application for extra protection.Overload relay can avoid serious damage for electric motor when overload happen to our system with proper setting.

The increased temperature opens the contacts through a bimetallic strip or by melting an alloy that activates a mechanism that opens the contacts depend on our setting for overload relay.This time i explain detail about common types of overload relay for motor control. read more

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Miniature Circuit Breaker Sizing

04/02/2011 by 64 Comments

When we design or build a electrical installation,we must know how to choose the suitable circuit breaker for the any application that we design.For electrician,this is compulsory knowledge.So here i want share my little knowledge about circuit breaker sizing method.

This calculation for sizing the miniature circuit breaker.For other circuit breaker likes MCCB,ACB,VCB,OCB and etc,it have a additional factor and calculation that we must consider.

For that why i will discuss it in my next post…so this time i want explain the simple way how to sizing the miniature circuit breaker for our application. read more

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PLC Programming

28/01/2011 by 1 Comment

How we can make the PLC functioning properly to control the machine?We need to stored the PROGRAMMABLE CONTROL SYSTEM  into the PLC memory.We need the special PLC PROGRAM to written the PLC language.For that task..we need the PC or LAPTOP to run the programming software :D

After we make a sketch for the diagram control circuit,we need to transfer into the Programming Language using the special software provide by PLC maker. This a the best part when we need to draw the diagram into the program.We need study the user manual first before can done properly :D

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Magnetic Contactor

21/01/2011 by 5 Comments

Magnetic contactor is common used in automation industry for motor control application.It is function basically like “relay”.The power source into the coil of winding,it like the solenoid operation.It can delivery a big ampere to  the loads and very long lasting and high durability.

When the power is “on”,it energized the coil and make plunger move and the switch contact is change from normally open to closed position.It allowed the current move from input terminal to output terminal.Then if we connected to the 3 phase motor,it will running :D

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Direct on line starter

08/10/2010 by 32 Comments

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

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Motor Overload Protection

07/10/2010 by 9 Comments

Overload protection is installed in the main control circuit or power line of motor to protect from damage due to mechanical malfunction overload conditions when it is running.

The effect of an overload is an excessive rise in temperature in the motor windings due to current higher than full load current.

Properly sized overload protection disconnects the motor from the power supply when the heat generated in the motor circuit or windings approaches a damaging level for any reason. Read More

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