Relays used for i. as interfaces between control circuits and load circuits, ii. This article briefly discusses the relay basics & different types of relays that are utilized for a variety of applications. enumerated the advantages of PLC over the traditional relay logic. 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. Microprocessors, which are made of millions of semiconductors, are now more powerful than ever before. 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 Several setting groups: Wider range of parameter adjustment: Communications built in (serial, Ethernet, teleprotection, etc.) Relays are the essential component for protection & switching of a number of the control circuits & other electrical components. Communication and interoperability. Programmable relays are best in simple applications that won’t need to be changed often. Due to the inherent characteristics of the components that make up the solid … Advantages of Solid-State Relays Over Electro-Mechanical Relays. PLC Motor Controls. 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. Static relays are sensitive to voltage transients which are caused by operation of breaker and isolator in the primary circuit of CTs and PTs. 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. Nowadays large rigid relay based control systems are being replaced with PLCs. 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…. 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. A simple architecture of PLC is shown in figure below. To sort these issues, Programmable logic controller (PLC) was introduced. Programmable Relay Advantages. 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. April 29, 2020 November 13, 2019 by Rick Phillips. Space advantages. 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. Induction Relay. Electromechanical relays (EMRs) and Solid state relays (SSRs) are designed to provide a common switching function. Mathematically, gamma distribution and Weibull distribution competes with each other in determining the reliability of a system. Problem like Arcing, Replacement of contacts is necessary. Fig. Electromagnetic Relay. 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. 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. 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. In an automated control system the main advantages of a PLC over relays are: Easier to develop complex logical expressions with ladder logic software. Moving contacts are present. Its economic advantage is its massive production of goods thereby lowering price. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. 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. Electromagnetic Relays General technical information. larger cable ducts). They have a lot of advantages over semiconductor switches, though those advantages have been eroded with the improvements of MOSFETs, IGBTs, SCRs and Triacs. So, No problem of Arcing No needs to replace contacts. It will take much longer time to replace all electromagnetic relays by micro processor based static relays. What are the advantages and disadvantages of PLC (Programmable Logic Controls) over traditional relay wiring controls? An EMR provides switching through the use of electromagnetic devices and sets of contacts. The advantages of solid-state relays … Borrowing some design ques from PLCs, programmable relays have several inputs and outputs. PLCs have a lot more functions that just use like relay contacts, though they were first made to replace relays. TABLE 2 – Advantages of numerical relays over static relays. When this operating current increases, coil energizes the electromagnet. One can argue that something complex is not necessarily better than a comparable simpler product that does the same task. Upvote (2) Views (38852) Followers (1) Write an Answer Register now or log in to answer. The performance of CT under short-circuit condition is also improved. On the other hand, a row of 10-20 relays can be twice the length, and require twice the amount of wiring (i.e. 1: Graphical Representation Of PLC. Weibull distribution can also be used to determine the failure rate. What is PLC? Relay logic). While manufacturers have largely moved over to programmable logic for these tasks, relays offer a simple and cheap alternative. Static Relays Electromagnetic Relays; Power consumption: Very less 1 milliwatt: High 2 watt: Moving contacts: No moving contacts. However, the more complex SSR might just win you over when it comes to performance. The armature is the moving part that opens and closes the contactors. 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. All the Relays react to voltage or current with the end goal that they open or close the contacts or circuits. The electromagnet controls opening and closing of the contactors in the relay. Increased reliability with PLC life easily reaching +10years, Easier and cheaper to modify or expand the control system at a later date. Electromechanical relays are actuated electromechanically. 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. The installation itself is a big argument in favor of PLCs. Electromagnetic relays are those relays which are operated by electromagnetic action. Relays contain several parts to make them work. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. 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. Since from 1970 PLCs (Programmable Logic Controllers) have become most common choice for manufacturing / process control. 3 Answers; Answer added by Deleted user 6 years ago . Thus a PLC can perform many functions with the same hard wiring. 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. Advantages of Numerical relays 1. In Electromagnetic relays operating current flows through the coil. 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. CB monitoring … 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. PLCs bring numerous advantages in simplicity, accuracy, and cost.. However, static overcurrent relays offer several advantages over the electromagnetic form: ADVERTISEMENTS: 1. Installation . Longer life and higher reliability During initial operation, both types of relay show similar levels of reliability. INTEGRATED CIRCUITS DIVISION 2 R03 Application Note: AN-145 1. PLC • In old days, electrical control was mostly based on relays (Contactors) (i.e. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. But a Programmable Logic Controller, PLC is a mini computer which can take decision based on the programme and its input & output. A small PLC can be roughly the size of a house brick. Solid State Relays vs. Electromagnetic Relays Wed, Dec 06 by 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). In Electromagnetic relays operating current flows through the coil. Induction Type Relays. These relays are known as control relays because they control the relays that control the switch that turns the motor ON and OFF. Reduced design, installation and component costs. Believe it or not there is a lot of engineering in the design of a relay. Compact Size Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. Some programmable relays can include over 20 inputs and outputs. They also provide relay, timer, and counter functions in a single unit. Internal Fault diagnosis: Power system measurements available: Distance to fault locator: Disturbance recorder: Auxiliary protection functions (broken conductor, negative sequence, etc.) for signal multiplication, iii. Question added by Aleoden Casan , Electrical T & C Engineer , ALYSJ JV Date Posted: 2014/01/07. 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). Virtually maintenance free compared to relays. Where space is at a premium, a PLC is often a better option. When this operating current increases, coil energizes the electromagnet. 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. An SSR depends on electronic devices such as SCRs and triacs to switch without contacts. It is typically actuated with an electromagnet. 9 Reasons Why PLC is used over Microcontrollers. Because there are no moving parts, they can work in a high shock and vibration environment. These are used as protective relays in AC systems alone and are usable with DC systems. 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. The solid state device completes the contact function. Initially industries used relays to control the manufacturing processes. 2. Relays are electro-mechanical switches that have coil and two types of contacts that is NO & NC.