Virtually maintenance free compared to relays. Internal Fault diagnosis: Power system measurements available: Distance to fault locator: Disturbance recorder: Auxiliary protection functions (broken conductor, negative sequence, etc.) 3 Answers; Answer added by Deleted user 6 years ago . Serious over voltage is also caused by breaking of control circuit, relay contacts etc. Increased reliability with PLC life easily reaching +10years, Easier and cheaper to modify or expand the control system at a later date. April 29, 2020 November 13, 2019 by Rick Phillips. 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 have a lot more functions that just use like relay contacts, though they were first made to replace 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. These relays are known as control relays because they control the relays that control the switch that turns the motor ON and OFF. 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. Installation . An SSR depends on electronic devices such as SCRs and triacs to switch without contacts. Relays are electro-mechanical switches that have coil and two types of contacts that is NO & NC. Where space is at a premium, a PLC is often a better option. The armature is the moving part that opens and closes the contactors. Static Relays Electromagnetic Relays; Power consumption: Very less 1 milliwatt: High 2 watt: Moving contacts: No moving contacts. Static relays are sensitive to voltage transients which are caused by operation of breaker and isolator in the primary circuit of CTs and PTs. One can argue that something complex is not necessarily better than a comparable simpler product that does the same task. What are the advantages and disadvantages of PLC (Programmable Logic Controls) over traditional relay wiring controls? It will take much longer time to replace all electromagnetic relays by micro processor based static relays. Several setting groups: Wider range of parameter adjustment: Communications built in (serial, Ethernet, teleprotection, etc.) 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). So, No problem of Arcing No needs to replace contacts. What is PLC? Nowadays large rigid relay based control systems are being replaced with PLCs. Electromechanical relays (EMRs) and Solid state relays (SSRs) are designed to provide a common switching function. Electromagnetic Relay. Question added by Aleoden Casan , Electrical T & C Engineer , ALYSJ JV Date Posted: 2014/01/07. The performance of CT under short-circuit condition is also improved. All the Relays react to voltage or current with the end goal that they open or close the contacts or circuits. 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. Borrowing some design ques from PLCs, programmable relays have several inputs and outputs. Advantages of Solid-State Relays Over Electro-Mechanical Relays. Relays are the essential component for protection & switching of a number of the control circuits & other electrical components. PLCs bring numerous advantages in simplicity, accuracy, and cost.. Thus a PLC can perform many functions with the same hard wiring. In Electromagnetic relays operating current flows through the coil. Induction Relay. Upvote (2) Views (38852) Followers (1) Write an Answer Register now or log in to answer. PLC • In old days, electrical control was mostly based on relays (Contactors) (i.e. PLC Motor Controls. TABLE 2 – Advantages of numerical relays over static relays. However, static overcurrent relays offer several advantages over the electromagnetic form: ADVERTISEMENTS: 1. Fig. Advantages of Numerical relays 1. Longer life and higher reliability During initial operation, both types of relay show similar levels of reliability. To sort these issues, Programmable logic controller (PLC) was introduced. Problem like Arcing, Replacement of contacts is necessary. It is typically actuated with an electromagnet. Believe it or not there is a lot of engineering in the design of a relay. 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. Because there are no moving parts, they can work in a high shock and vibration environment. Weibull distribution can also be used to determine the failure rate. 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). They also provide relay, timer, and counter functions in a single unit. These are used as protective relays in AC systems alone and are usable with DC systems. Compact Size Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. Reduced design, installation and component costs. Since from 1970 PLCs (Programmable Logic Controllers) have become most common choice for manufacturing / process control. The solid state device completes the contact function. Communication and interoperability. INTEGRATED CIRCUITS DIVISION 2 www.ixysic.com R03 Application Note: AN-145 1. Relays used for i. as interfaces between control circuits and load circuits, ii. In an automated control system the main advantages of a PLC over relays are: Easier to develop complex logical expressions with ladder logic software. One of the advantages of electromechanical relays over solid-state switches is that relays have much lower contact resistance. 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. 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. Induction Type Relays. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. The electromagnet controls opening and closing of the contactors in the relay. The installation itself is a big argument in favor of PLCs. An EMR provides switching through the use of electromagnetic devices and sets of contacts. While manufacturers have largely moved over to programmable logic for these tasks, relays offer a simple and cheap alternative. 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