Advantages of Numerical relays 1. Electromechanical relays (EMRs) and Solid state relays (SSRs) are designed to provide a common switching function. Relay logic). relays have an advantage over lower-cost electromechanical relays in industrial automation applications due to higher reliability and longer life, but these are not the only advantages…. In an automated control system the main advantages of a PLC over relays are: Easier to develop complex logical expressions with ladder logic software. Mathematically, gamma distribution and Weibull distribution competes with each other in determining the reliability of a system. Motor protection in industrial applications has come a long way over the past 30 years, from bimetallic and eutectic alloy overloads to basic solid-state overloads and what are often referred to today as motor management relays. The actuating force for contact movement is developed by a moving conductor that may be a disc or a cup, through the interaction of electromagnetic fluxes due to fault currents. While manufacturers have largely moved over to programmable logic for these tasks, relays offer a simple and cheap alternative. 9 Reasons Why PLC is used over Microcontrollers. Programmable relays are best in simple applications that won’t need to be changed often. Static Relays Electromagnetic Relays; Power consumption: Very less 1 milliwatt: High 2 watt: Moving contacts: No moving contacts. They also provide relay, timer, and counter functions in a single unit. Increased reliability with PLC life easily reaching +10years, Easier and cheaper to modify or expand the control system at a later date. Reduced design, installation and component costs. Thus a PLC can perform many functions with the same hard wiring. Internal Fault diagnosis: Power system measurements available: Distance to fault locator: Disturbance recorder: Auxiliary protection functions (broken conductor, negative sequence, etc.) Low CT burden – The VA consumption of static overcurrent relays is quite low (7 mVA to 100 mVA) as compared with that of electromagnetic relays (1VA to 3VA) so that smaller CTs are required. One of the advantages of electromechanical relays over solid-state switches is that relays have much lower contact resistance. These are the different types of electromagnetic relays. Induction Relay. Relays contain several parts to make them work. Its economic advantage is its massive production of goods thereby lowering price. These are used as protective relays in AC systems alone and are usable with DC systems. Solid State Relays vs. Electromagnetic Relays Wed, Dec 06 by ATO.com Solid state relay (SSR) is a non-contact switch composed of solid-state electronic components, achieving the connecting and disconnecting circuits without contact and sparking based on the virtue of the electronic components (such as switching transistors, triacs and other semiconductor components). enumerated the advantages of PLC over the traditional relay logic. Auto relays can be used to perform both simple and more complex logical tasks such as - momentary inputs and time controlled functions, for example - the time control operation of wiper blades and the interior light time delay. Virtually maintenance free compared to relays. April 29, 2020 November 13, 2019 by Rick Phillips. TABLE 2 – Advantages of numerical relays over static relays. When this operating current increases, coil energizes the electromagnet. I could keep going, but I think you get the picture of how machines were controlled pre-PLC, and, more importantly, I think you start to see some of the problems with this system of electromechanical control via relays. These relays are known as control relays because they control the relays that control the switch that turns the motor ON and OFF. Due to the inherent characteristics of the components that make up the solid … When the operating current becomes large, the magnetic field produced by electromagnet is high such that this magnetic field pulls the armature or plunger making the trip circuit contacts to close. Advantages of Solid-State Relays Over Electro-Mechanical Relays. When the operating current becomes large, the magnetic field produced by electromagnet is high such that this magnetic field pulls the armature or plunger making the trip circuit contacts to close. PLC advantages compared to electro mechanical relays 1.Ability to interface / communicate with computers 2.Simple programming 3.High reliability 4.Easy maintenance 5.Rugged construction - can operate in extremely harsh conditions 6.Small size 7.Easy expandability 8.Economical in long term 2. An SSR depends on electronic devices such as SCRs and triacs to switch without contacts. An EMR provides switching through the use of electromagnetic devices and sets of contacts. In Electromagnetic Attraction Relays, there is a coil which energises an electromagnet.When the operating current becomes large, the magnetic field produced by an electromagnet is so high that it attracts the armature or plunger, making contact with the trip circuit contacts.These are the simplest type of relays. Induction Type Relays. What are the advantages and disadvantages of PLC (Programmable Logic Controls) over traditional relay wiring controls? PLCs have a lot more functions that just use like relay contacts, though they were first made to replace relays. for signal multiplication, iii. Where space is at a premium, a PLC is often a better option. contact unit using electromagnetic attraction, which is produced when electric current exceeding the specified value flows to the electromagnet; the voltage and current (input signal) applied to the coil opens or shuts the contact. 1: Graphical Representation Of PLC. Weibull distribution can also be used to determine the failure rate. Believe it or not there is a lot of engineering in the design of a relay. The advantages of solid-state relays … PLC • In old days, electrical control was mostly based on relays (Contactors) (i.e. Relays are the essential component for protection & switching of a number of the control circuits & other electrical components. Question added by Aleoden Casan , Electrical T & C Engineer , ALYSJ JV Date Posted: 2014/01/07. All the Relays react to voltage or current with the end goal that they open or close the contacts or circuits. Ever since the semiconductors were invented, the electronics industry grew exponentially at an exceedingly high rate in terms of the number of electronic devices produced each year. One can argue that something complex is not necessarily better than a comparable simpler product that does the same task. Electromechanical relays are a relatively old technology that use a simple mechanical design approach, whereas solid state relays are much newer and advanced—and yes, more complex. Nowadays large rigid relay based control systems are being replaced with PLCs. Fig. However, the more complex SSR might just win you over when it comes to performance. Since the introduction of solid-state relays some decades ago, the debate over which is better, solid-state relays (SSRs) or electromechanical relays (EMRs), has gone on. Borrowing some design ques from PLCs, programmable relays have several inputs and outputs. Electromagnetic Relays General technical information. The electromagnet controls opening and closing of the contactors in the relay. larger cable ducts). When this operating current increases, coil energizes the electromagnet. Today Beijing Hemanton Electromechanical Equipment Co., Ltd. will share with you the advantages of solid state relays: 1 Solid state relays have no mechanical parts. Relays are electro-mechanical switches that have coil and two types of contacts that is NO & NC. The solid state device completes the contact function. Communication and interoperability. CB monitoring … The installation itself is a big argument in favor of PLCs. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. In Electromagnetic relays operating current flows through the coil. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. Because there are no moving parts, they can work in a high shock and vibration environment. One is generally called ‘‘Low Power Relays’’ or ‘‘Power Relays’’ (both terms mean the same, that is, a low-power electromagnetic relay with a swi tching current not exceeding 30 A). However, static overcurrent relays offer several advantages over the electromagnetic form: ADVERTISEMENTS: 1. Problem like Arcing, Replacement of contacts is necessary. PLCs bring numerous advantages in simplicity, accuracy, and cost.. Space advantages. Programmable Relay Advantages. Since from 1970 PLCs (Programmable Logic Controllers) have become most common choice for manufacturing / process control. Some programmable relays can include over 20 inputs and outputs. Electromagnetic relays are those relays which are operated by electromagnetic action. 3 Answers; Answer added by Deleted user 6 years ago . Compact Size Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. Electromechanical relays are actuated electromechanically. Longer life and higher reliability During initial operation, both types of relay show similar levels of reliability. The armature is the moving part that opens and closes the contactors. To sort these issues, Programmable logic controller (PLC) was introduced. A small PLC can be roughly the size of a house brick. The relay control panels had to be regularly replaced, consumed lot of power and it was difficult to figure out the problems associated with it. On the other hand, a row of 10-20 relays can be twice the length, and require twice the amount of wiring (i.e. PLC Motor Controls. The performance of CT under short-circuit condition is also improved. Introduction Many electronic designs can take advantage of the improved performance of solid-state relays (SSRs) relative to that of electro-mechanical relays (EMRs) that perform the same circuit function. In Electromagnetic relays operating current flows through the coil. This article briefly discusses the relay basics & different types of relays that are utilized for a variety of applications. Relays used for i. as interfaces between control circuits and load circuits, ii. Installation . Electromagnetic Relay. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. So, No problem of Arcing No needs to replace contacts. A simple architecture of PLC is shown in figure below. But a Programmable Logic Controller, PLC is a mini computer which can take decision based on the programme and its input & output. The fast advance of electronic components, especially integrated circuits, over the past ten years did not lead – as was often prophesied – to a drop in the demand for relays. Initially industries used relays to control the manufacturing processes. Upvote (2) Views (38852) Followers (1) Write an Answer Register now or log in to answer. Programmable Logic Controllers (PLCs) may not have been the best automation solutions when they were first introduced, but with astronomical technological advancements over the last few decades they have surpassed the more traditional hard wiring. It is typically actuated with an electromagnet. What is PLC? It will take much longer time to replace all electromagnetic relays by micro processor based static relays. Microprocessors, which are made of millions of semiconductors, are now more powerful than ever before. 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