It uses an electromagnet - the relay coil - to physically move a mechanical switch. The disadvantages of a conventional electromechanical relay are overcome by using micro controller for realizing the operation of the relays. Electromagnetic Relay basics. This page covers advantages and disadvantages of Frame Relay. Over time, however, the solid state relay will gain the edge due to its main advantage: there are no moving parts. What is a programmable relay? The basic static differential relay scheme is shown in the Fig.2. Answer : Low power consumption as low as 1mW; No moving contacts; hence associated problems of arcing, contact bounce, erosion, replacement of contacts; No gravity effect on operation of static relays. The main part of a relay is the electromagnet. Static Relays A static relay is the relay which uses solid state components like transistors ,diodes etc.,for the measurement or comparison of electrical quantities. The choice of a protection relay rather than some other device is logical as the protection relay is probably the only device that is virtually mandatory on circuits of any significant rating. Learn about some of the advantages that PLC systems have over a relay system. It will take much longer time to replace all electromagnetic relays by micro processor based static relays. Drawbacks or disadvantages of Solid State Relay. An alternator stator winding protected by a % differential relay is as shown in fig. Numerical Relay 4.1 Introduction Nowadays the modern power system have grown both in size and complexity so it require fast ,accurate and reliable protective schemes to protect major equipment and … Electro Magnetic Relay •In an electromagnetic relay, the operating torque is produced by the electromagnetic attraction/electromagnetic induction/thermal effects of electric current. The construction and working of a relay can be understood from the above diagram. A static relay may have one or more programmable units such as microprocessors or microcomputers in its circuit. The term ‘static’ implies that the relay has no … In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion . E.g. An electromagnetic relay is an electromechanical device. It may cause damage to the relay contacts. The protection relay no longer performs a basic protection function but is an integral and major part of a substation automation scheme. Electromagnetic Relay . Requires periodic maintenance and testing unlike static relays. 1. SSRs employ semiconductor switching elements, such as thyristors, triacs, mosfet and transistors to switch the load current. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. The relay has less overloading capacity. 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. It also provides isolation between low power circuit and high power circuits. In Electromagnetic relays operating current flows through the coil. Electromagnetic relays uses an electromagnet to operate a switching mechanism mechanically. Electromagnetic relays are those relays which are operated by electromagnetic action. Today, we will dive into some of the advantages of PLCs. relay show similar levels of reliability. The IEEE defines protective relays as: “relays whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control circuit action ”. To overcome this difficulty, the air gap flux producing an electromagnetic force is divided into two fluxes acting simultaneously but differing in time phase. UNIT II - RELAY CIRCUIT Static relay circuit (using analog and digital ic’s) for over current: The Solid State Relay (Static Relay): History of Relay: The static relay are next generation relays .The Solid Static relays was first introduced in 1960’s. Electromagnetic relays are those relays which are operated by electromagnetic action. It also describes Frame Relay basics. The high-voltage working circuit includes a high-voltage power supply, a motor and the contacts of the electromagnetic relay. Hence can be … In contrast, the solid state relay has good electromagnetic compatibility (EMC). It is combined protection, monitoring and control system incorporated in the static system. 4. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. Following are the drawbacks or disadvantages of Solid State Relay: It's cost is very high. What is Frame Relay? A solid-state relay is less-commonly referred to by its acronym, SSR.It is sometimes regarded as an optocoupler, but in this encyclopedia the two components have separate entries.An optocoupler is a relatively simple device consisting of a light source (usually an LED) and a light sensor, in one package.It is used primarily for isolation rather than to switch a high current. The timing circuit gives desire time log i.e. below. (nov/dec 2011) Low power consumption as low as 1mW No moving contacts; hence associated problems of arcing, contact bounce, erosion, replacement of contacts No gravity effect on operation of static relays. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. And the solid state relay with zero-crossing function can reduce the influence of external interference on SSR, and also reduce the interference signal generated by the solid-state relay itself. Introduction: The frame relay is used for data transmission at higher speed similar to ISDN. There are many advantages that a PLC system holds over a relay system. Reliability. The static relay is more costly as compared to the electromagnetic relay. Question 41. And strong electromagnetic interference will even damage the human body. A solid-state relay is an electronic switch that operates without the moving parts of an electro-mechanical relay. The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. Compact Size. if time lag is set at 1 sec, then relay waits for 1 sec after the fault and when 1 sec is over, then only relay starts operating. The relay is an electromechanical switch used as a protecting device and also as a controlling device for various circuits, equipments, and electrical networks in a power system. The performance of static relay is better than electromagnetic relays as they are fast acting and accuracy of measurement is better than electromagnetic relay. The switch may be either single pole or double pole and there may be many separate switches all controlled by the same relay coil. The picture shows a high power relay. Usually an electromagnetic relay has two circuits, low-voltage control circuit and high-voltage working circuit.The low-voltage control circuit includes an electromagnetic relay coil, a low-voltage power supply and a switch. relay operates after some time only. Therefore solid state relays are also called as static relays. •The restraining torque is produced by the springs F F F or Fo is the operating force. What Are The Advantages Of Static Relay Over Electromagnetic Relay? Electromagnetic Relay. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. This causes resulting electromagnetic force to … solid-state relay . All the Relays react to voltage or current with the end goal that they open or close the contacts or circuits. It is bound by specific current/voltage characteristics. Relay. The over or under current and voltage protection of various a.c.and d.c.equipments. It will take much longer time to be replaced the all electromagnetic relays by micro processor based static relays. are required to construct this protective relay.. Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason … Fr … What are the advantages of static relay over electromagnetic relay? One of the first and simplest advantages is reliability. The various advantages of static differential relay over electromagnetic differential relay are, highly sensitive, compact, and very fast in operation, low power consumption, less burden on input CTs and inrush current proof characteristics. When this operating current increases, coil energizes the electromagnet. 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. Disadvantages or demerits: High burden level instrument transformers are required (CTs and PTs of high burden is required for operating the electromagnetic relays compared to static relays) The directional feature is absent in electromagnetic relays; Requires periodic maintenance and testing unlike static … Some of the advantages, disadvantages and … The static network is so designed that it gives an output signal in the tripping direction whenever a threshold conditions reached. The electromechanical relay can be defined as an electrically operated switch that completes or interrupts a circuit by physical movement of electrical contacts into contact with each other. This causes the relay to hum and produces a noise. 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