What You Need To About A Thermal Relay?

On March 22, 2018   /   Thermal Relay   /   Leave a comment
What You Need To About A Thermal Relay?

A relay is a device used for switching and is used in many electrical as well as electronic circuits. It acts as shield guard against extra voltage, current or even heat and protects the gadget as well enable the gadget to perform with great efficiency. As per the expert’s relays are types of switch controlled by an electric current. Basically, relays can be utilized safely switch from low to high voltages and currents. Though there are many types of relays used in the various application, this short article is primarily written to educate the readers and other enthusiasts about the Thermal Relay which is widely used in the areas such as motor control, temperature control devices both in homes as well as in large factories.

Working Principle of Thermal Relays and its Construction

In general, a thermal relay also known as Thermal Overload Protection Relay (TOPR) is a simple device which offers over current protection for all motors used in various applications in homes or in the industries. Basically, this TOPR prevents the motor when it gets overloaded and produces heat as a result. Such events occur when there is an excess current drawn by the motor, and if continued for long, it can ruin the motor itself. In this context, a TOPR is installed which can sense the excess heat and switch off the motor circuit and thereby prevents serious damages.

Let us know what a thermal overload relay is all about. As the general law in physical science, various metals have a different coefficient of thermal expansion. When two different metals which are joined together are heated the metal which has a higher value of the coefficient of thermal expansion will expand more than the other one, and it causes a bend in this bimetallic strip. All the TOPR works in this principle and the switches used in these relays are fitted with the bimetallic strips so that it can trip off when the temperature goes high in the applied motor.

Let us know what a thermal overload relay is all about. As the general law in physical science, various metals have a different coefficient of thermal expansion. When two different metals which are joined together are heated the metal which has a higher value of the coefficient of thermal expansion will expand more than the other one, and it causes a bend in this bimetallic strip. All the TOPR works in this principle and the switches used in these relays are fitted with the bimetallic strips,o that it can trip off when the temperature goes high in the applied motor.

The design of the TOPR is known to be critical, and the relays are made for various specifications and hence used in different applications. Here one should remember the fact that a motor during its general operation produces a certain amount of heat due to self-induction. Hence while designing these thermal sensitive relays, a designer has to consider the optimum temperature generated by the motors and accordingly the suitable relays are to be added to the circuit. This factor is considered to be critical, and hence the buyers need to use the correctly rated relays that can produce the expected results by switching off the motor when there is an excess heat than the desirable thermal level.

Read Also : The Latest Solid State Relays

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The Latest Solid State Relays

On February 16, 2018   /   Solid State Relays   /   Leave a comment
The Latest Solid State Relays

Overview of Solid State Relays

Technology always keeps changing. Earlier there were transistors that led to the use of television in every home. Later the electromagnetic relay came that produced high current and found use numerous operations. Today, there are solid state relays that work on a microprocessor. Solid State Relays have no moving parts. The electromagnetic relay had springs, magnetic field, and mechanical contacts. The SSR has properties of a solid-state semiconductor both optical and electrical. It performs the input to output isolation by using the semiconductor. It performs switching functions very well. There is much more to it and not just changing, that gives it an extensive scope in the future.

It is somewhat similar to the electromagnetic relays as well. For instance, SSR also provides total electrical isolation like it happens in an electromagnetic relay. It provides resistance to some infinite value when nonconduction or the circuit is open. On the other hand, when the circuit is closed, it has negligible resistance producing high current. It has the capability of getting designed as an AC or DC switch both. It uses TRIAN, SCR or switching transistor to make it happen. It is different from the mechanical contacts that were used earlier in a relay.

Fundamentally, there are no differences between an SSR and electromagnetic relay. The main advantage SSR has over the traditional relays is that it operates without the use of any moving part. Hence, the name a solid state relay. There are no issues of contacts get detached from each other due to moving parts. There is no chance of wear and tear happening as only solid parts are present in its construction. The On and OFF function takes places much faster as the chance of contacts get bounced up is very less.

There are no electrical noises produced due to the turn-off and turn on in case of zero current state and zero voltage state respectively. Elimination of electrical sounds is a great relief at times. Therefore SSR is gaining popularity slowly over the electromagnetic relays. One can buy it in its standard form that is an off the shelf pack that has ranges of few amperes of volts to several hundreds of amperes and volts. The output switching capability can be customized or bought in its standard form depending on your requirement. There are plenty of options as there are different current and voltage ranges available in the market.

Companies are making SSR make sure customers have plenty of options in the standard product itself. The operation of SSR is similar to that of the electromagnetic relay where even a small voltage input can result in very high voltage output. SSR takes less room than an electromagnetic relay and is much faster in operation. An SSR can operate by creating an Opto coupling instead of using magnetic fields for providing isolation. The type of switching device used decides whether the output of SSR will be AC or DC. Its functioning could be understood very well by referring to its diagrams. However, the fundamental principle is not hard to understand and can be learned quickly if you operate one.

Read Also : What You Need To About A Thermal Relay?

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