260 0 obj <>stream The testing and servicing is simplified. o No gravity effect on operation of static relays. 11. Delay in operation: Easily provided Solid state relays have been around for decades. Like other electromagnetic relays, it can … The following are the benefits of static relays. Production methods and quality systems have improved a great deal over … The constraint in static relay … The various advantages of static relays are: 1. When this operating current increases, coil energizes the electromagnet. Electromagnetic Relay . In fact, both of them provide isolation between the input and output circuit. Fault current level detectors are termed overcurrent relays. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. there are different types of relay used in electrical field. 10. Electromagnetic relays are those relays which are operated by electromagnetic action. 2. Numerical relays are natural developments of digital relays due to advances in technology. 11. Magnetic latching relay is a new type of relay developed in recent years. 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. 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. An EMR provides switching through the use of electromagnetic devices and sets of contacts. 03. Hence can be used in vessels ie, ships, aircrafts etc. Compact Size. Advantage of plc over relay : #6. (1 relay can be used as over current relay, under voltage relay etc.) 7. Today, we will dive into some of the advantages of PLCs. They use one or more digital signal processors (DSP) optimised for real time signal processing, running the mathematical algorithms for the protection functions. The moving parts are absent. The static relays are replacing all electromagnetic relays like induction cup relays for distance and directional protection and disc relays for over current protection (except the attracted armature relays and DC polarized relays), because these relays control can many circuits at low costs. The distinction between digital and numerical relays is particular to Protection. These relays require to be calibrated periodically and tested. Thus they are bulky in size. What are the advantages of static relay over electromagnetic relay? ��r�5���s����.. The burden or current transformers gets considerably reduced thus smaller CT.s can be used. These are subjected to differential forces under fault conditions and hence required to have delicate setting of small contact gaps, special bearing arrangements, clutch assemblies etc. h�bbd``b`q�'��,�`��� �k�� b���\7���u $ "Aܽ �� n!�`0�)���[email protected]�ȀX�@�U�c�r�-H�2��qp��#�3�} ` DYg The moving parts are absent. The transistor circuits can perform functions like summation, integration, comparison etc. Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays… Reliability. This is because transistor can be used as an amplifying device as well as a switching device. The VA burden of these relays is higher than static and numerical relays. h޴X�r�8����]SN�j*U�-��؎Wrn夦h �8�H��o��{$%�R�3ƭh }��#,!CW��� G"�˵@H�}(��P�%�͹*�\ ��܆�p��+\#�a�}��@�[email protected] An SSR depends on electronic devices such as SCRs and triacs to switch without contacts. 3. When this operating current increases, coil energizes the electromagnet. Hence can be used in vessels ie, ships, aircrafts etc. Benefits or advantages of Solid State Relay. 10. … Types of Relay. Electromagnetic Relay Definition: Electromagnetic relays are those relay which operates on the principle of electromagnetic attraction. The first static relays developed were the high speed differential relays and the distance relays. %PDF-1.6 %���� When the operating current becomes large, the magnetic field produced by electromagnet is high such that this magnetic field pulls the armature or plunger making the trip circuit contacts to close. The coupling, between the input circuit and the output circuit, is optical. Q: What are the advantages of static relay over electromagnetic relay? The conventional electromagnetic relays use the moving parts such as an armature, disc etc. The resetting time can be reduced and overshoots can be reduced due to absence of mechanical inertia and thermal storage. Solid state relays don't have this mechanism, but can fail more easily in over current or over voltage conditions. 5. The static relay consumes very less power because of which the burden on the measuring instruments decreases and their accuracy increases. Comparison of Static and Electromagnetic Relays. Advantages of Numerical relays 1. When this operating current increases, coil energizes the electromagnet. The power consumption is very low as most of the circuits are electronic. Advantages of Static Relays The various advantages of static relays are: 1. The performance of static relay is better than electromagnetic relays as they are fast acting and accuracy of measurement is better than electromagnetic relay. 9. h�b```a``Ne`e`P�``@ �+P�� ��"S�f���Œۙ��kE�r�a��1����X�\5$}��U��s�� .Y~���״c���jf�?g�n������Ӓ~��v:[f����¢�mf�S�v_��?��ʜ9k%�v\e~�S+Z]�M|��D�,X�瘩���������s�LI�`�`�`��ca����^] �[email protected],3^~ˋ��q�82t�juP Current relay can be divided into electromagnetic current relay and static current relay by structure type. 0 It will take much longer time to be replaced the all electromagnetic relays by micro processor based static relays. The performance of static relay is better than electromagnetic relays as they are fast acting and accuracy of measurement is better than electromagnetic relay. Magnetic latching relay. Hence can be used in vessels ie, ships, aircrafts etc. ��[d�����K'���,�'��?i㓛p��Ep4004�Ҍ�ǁ�)ӧ �Yl8��4���-����� ȳ�5 The sensitivity is high as signal amplification can be achieved very easily. These relays are robust and highly reliable. 6. These relays use thyristors and triacs for their operation. In Electromagnetic relays operating current flows through the coil. Give the block diagram of static relay indicating its basic elements. The Solid State Relay (Static Relay) Overview (on photo: Basler Electric BE1-27 Solid State Protective Relay, Over/Under Voltage) jiguparmar The Solid State Relay (Static Relay) Overview History of Relay The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. What is the need for protective gear in power system? A wide range of control application #8. speed of operatio.scan time in mili second The low energy levels required in the measuring circuits make the relays smaller and compact in size. �A]Z�r)�"W"p�/m�C:"�q���� )=.�B:`a��,S!t`� These relays suffer from the effects of age. o No moving contacts; hence associated problems of arcing, contact bounce, erosion, replacement of contacts. Solid State Relays (SSR). ... State the advantages of over current relays over electromagnetic relays. Functions: 1 relay can perform various functions. Electromechanical relays (EMRs) and Solid state relays (SSRs) are designed to provide a common switching function. a power switching solution that can be used to allocate power without manually opening and closing the switch _���ޑ�n踌�x�K���4�R�? ���v���`;�9���I��}�{8���b�S�RM��MN��ơ�S�o�nt�O'p�"��wp��.�r�kM� IӄrJ(�JcC�4�9�5�{x�8��#*薮x6��4ɒ$� ���D_�U)7���"���N��X9�(a�_�z��*p����e��o{����V��8�;����丞�Uh�ʷM��(2��s$��&u}�u�*����Z�l�����"�pKY���7�M�Y�-W嶽���_��k-��u�:Ҍ*Mz��*d0�'����@��� B&p�)}��_s �����Gm� <5�.��IpTع���'�� ���P�(�3o �s�� 1�Ӹ(u�{�w`��MV�"f��M�����Ǫir���J%�H�˿A� ci�|Fo4��Oئ���~a;�Ńe{5��[email protected]���+���m��B܆�p�;?ŭ��օ���dȁ�mR����9�ĒۤFc�m�q���#�d�x����z%ϭ��j$�j�j��V]g9�#�h챬�]�2ω������k7���~�Ӥ�}���a�kBˣi]�v�@VE�ytr� >�@cP�x��r�(�B��`�D��Zj*)�. some of the relay like over voltage, over current protection , under voltage protection, earth fault protection. The static relay gives the quick response, long life, high reliability and accuracy and it is shockproof. It is a type of a magnetic switch which uses the magnet for creating a magnetic field. What are the advantages of static relay over electromagnetic relay? It is also an automatic switch. It is smaller in size. No gravity effect on operation of static relays. 8. The static relay consumes very less power because of which the burden on the measuring instruments decreases and their accuracy increases. Solid State Relay Advantages over Electromagnetic Relay Actually, the main objective of using any relay is to control or switch a large amount of current, voltage, power using low current or voltage, so both SSR and EMR provides the same function. The current and potential transformers are subjected to high burdens in case of electromagnetic relays. Since that time, it has gradually evolved from very large, relatively crude parts to the small, ultra-reliable parts we have today. o Low power consumption as low as 1mW. The use of printed circuits eliminates the wiring errors and mass production is possible. endstream endobj startxref 3. In some Industry, there is a redundant system for example if one pump fails the second pump will automatically start. Advantages and Disadvantages of Electromagnetic Relay There are many Advantages, ... burden level instrument transformers are required such that CTs and PTs of high burden is required for operating the electromagnetic relays compared to static relays. %%EOF It has very high life time. In Electromagnetic relays operating current flows through the coil. Following are the benefits or advantages of Solid State Relay: It offers very fast response usually about 1µs ON and 0.5 µs OFF. However, static overcurrent relays offer several advantages over the electromagnetic form:. A protective system is formed by static relays and electromechanical auxiliary relays. The static relays are commonly using the transistor circuits and called transistor relays. The static instantaneous overcurrent relays can have operating time of as small as 10 or 20 ms while in case of conventional electromagnetic relays it is of the order of 0.1 second. What are the advantages of static relay over electromagnetic relay? Give any two application of electromagnetic relays. 1 relay can perform only 1 function. Hence any functional characteristics as per the requirement can be obtained by the static relays. The static relay gives the quick response, long life, high reliability and accuracy and it is shockproof. Industrial relays. The reed relay was invented in 1936 by Bell Telephone Laboratories. endstream endobj 163 0 obj <> endobj 164 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text/ImageC/ImageI]/Properties<>/XObject<>>>/Rotate 0/Type/Page>> endobj 165 0 obj <>stream acknowledge failure means that you get warning that one has failed #7. o Low power consumption as low as 1mW o No moving contacts; hence associated problems of arcing, contact bounce, erosion, replacement of contacts o No gravity effect on operation of static relays. 193 0 obj <>/Filter/FlateDecode/ID[<29DECFBAB8BCD245B180C44BFA4A5175>]/Index[162 99]/Info 161 0 R/Length 130/Prev 198040/Root 163 0 R/Size 261/Type/XRef/W[1 2 1]>>stream In Electromagnetic relays operating current flows through the coil. (1 relay can be used as over current only for under voltage we use another relay). Hence, the Potential and the Current Transformers should have a higher capacity. Learn about some of the advantages that PLC systems have over a relay system. This relay has to be installed straight only and away from magnetic field. SSR are faster, quieter, smaller, more reliable, and last longer than electromagnetic relays. As electronic circuits can be used to perform number of functions, the wide range of operating characteristics can be obtained, which almost approach to ideal requirements. Fault Current Calculation using Symmetrical Components, Qualities of Protective Relaying - Reliability & Selectivity and Discrimination, Qualities of Protective Relaying - Speed and time & Sensitivity, Qualities of Protective Relaying - Stability, Adequateness & simplicity and economy, Terminologies used in Protective Relaying, Working Principle of Current Transformers, Construction of Wound type Current Transformers, Construction of Bar Type Current Transformers, Comparison of Current Transformer and Power Transformer, Errors in the Instrument Transformer - Ratio Error, Errors in the Instrument Transformer - Phase Angle Error, Reduction of Ratio and Phase Angle Errors, Advantages and Disadvantages of Instrument Transformers, Tripping Schemes In Circuit Breaker -Relay with Make Type Contact, Tripping Schemes In Circuit Breaker - Relay with Break type contact, Electromagnetic Attraction Relays - Attracted Armature Type Relay, Electromagnetic Attraction Relays - Solenoid and plunger type relay, Operating Principle of Electromagnetic Attraction Relays, Advantages, disadvantages and application of Electromagnetic Relays, Directional Induction Type Overcurrent Relay, Operation of Directional Induction Type Overcurrent Relay, Directional Characteristics of Induction Type Overcurrent Relay, High Impedance Differential Protection of Busbar, Comparison of Static and Electromagnetic Relays & Advantage of Static Relays, Limitations & Semiconductor Devices used in Static Relays, Short Circuit In R- L Series Circuit - Complementary Solution, Short Circuit in R- L Series Circuit - Particular Solution, Short Circuit in R- L Series Circuit - Complete Solution, Analysis of the complete solution of short circuit in RL series circuit, Current Interruption in A.C. The continuing reduction in the cost and size of microprocessors, memory and I/O circuitry leads to a single item … A protective system is formed by static relays and electro-mechanical auxiliary relays. ,�Ia�X�R���`��5);���P�F�:0���ï��J�fP�c�.�2�;��_������]�R,cZ�̖�ƹ��cJ�K؉���M��t!�9��ٕ2�S����ߙ�Quܟ��A�u�FWn�+;&[���m��:����j^���j]�ռNG�nt�6�nG�i�(�F��躍�V��]��u�q��R���t����z����緌���׍�2`H�'�p���O�Ye��0ҋ(��8K��D�o����8��()4�N���Rt��4�/ߌʨ�f�z�X���h?Z�x:+�oh�#]�P��ƚ��[email protected]=:�}zO#�@�v���I4-���0K�~?��ܓ��=e�v�1y�u�m�� ADVANTAGES OF STATIC RELAY The following are the benefits of static relays. These relays handle high currents and are long lasting. What is Relay: Generally we all are knows relay is used to protect the electrical equipment from abnormal condition. No bearing friction or contact troubles exist. There are many advantages that a PLC system holds over a relay system. The moving parts are present only in the actual tripping circuit and not in the control circuit. 1. Low power consumption as low as 1mW. The over or under current and voltage protection of various a.c.and d.c.equipments. Circuit Breakers, Requirements and Basic Action of a circuit breaker, Construction of Air blast Circuit breakers, Working of Air blast circuit breakers - Cross Blast Type, Working of Air blast circuit breakers - Axial Blast Type, Compressed Air System for Air Blast Circuit Breaker, Advantages, Disadvantages and application of Air blast circuit breakers, Construction of Air Break Circuit Breaker, Working and application of Air Break Circuit Breaker, Arc Extinction in Sulphur Hexafluoride Gas Circuit Breaker, Construction & Working of Non-Puffer Type Sulphur Hexafluoride Breaker, Single Pressure Puffer Type Sulphur Hexafluoride Circuit Breaker, Double Pressure Type Sulphur Hexafluoride Circuit Breaker, Advantages, disadvantages and application of Sulphur Hexafluoride Circuit Breaker, Vacuum Circuit Breakers & Electrical Breakdown In High Vacuum, Advantages, Disadvantages, application and characteristics of Vacuum Circuit Breaker, Factors Affecting Performance of Plane Break Oil Circuit Breaker, Advantages,disadvantages and applications, Self Generated Pressure Oil Circuit Breaker, Operation & Maintenance of Low Oil or Minimum Oil Circuit Breaker, Construction of Low Oil or Minimum Oil Circuit Breaker, Advantages, Disadvantages & Application of Low Oil or Minimum Oil Circuit Breaker, Development, Reliability & Commissioning tests, Introduction, applications and advantages of Distance Relays, Torque Equation & operating characteristics of Distance Relays, Operating Characteristics on R-X Diagram of Distance Relays, Use of Impedance Relay for Transmission Line Protection, Construction and disadvantages of Reactance Relay, Torque Equation & operating characteristics of Reactance Relays, Torque Equation & operating characteristics of Admittance Relays, Protection of Transmission Lines Against Direct Strokes, Protection of Transmission Line by Auxiliary Devices, Protection of Electrical Apparatus Against Travelling Waves, Classifications and specifications of surge diverters, Assemblies of Valve type Lightning Arrester, Location and testing of Lightning Arresters, Distance Relay Characteristics for transmission protection, Block Schematic of Carrier Aided Protection, Electronic Equipments of carrier aided protection, Phase Comparison Method of Carrier Current Protection, Definitions and available features of auto reclosing, Auto-reclosing - Medium Voltage Auto-Reclose, Auto-reclosing - High Voltage Auto-Reclose, Three-phase versus single-phase auto-reclose. 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. There are no physical moving parts involved in the design of solid state relay. Electromagnetic relays can fail over time as the contacts are damaged from making and breaking the circuit. The reset time of the relay is very less. 7�a]� �e����Bs����l�S��������8/J^y���ȆP�ؓ� �\�l["W�`�I9+.��������m��=���7~`��J The disadvantages of Electro-mechanical relays are. No moving contacts; hence associated problems of arcing, contact bounce, erosion, replacement of contacts. Thus there are lot of manufacturing difficulties and problems related to mechanical stability associated with electromagnetic relays. Compare the static relays to electromagentic relays. Some of the advantages, disadvantages and … One of the first and simplest advantages is reliability. The term ‘static’ implies that the relay has no moving mechanical parts in it. Hence there is no mechanical noise. The advantages of solid-state relays include the following: •SSRs are typically smaller than EMRs, conserving valuable real estate in printed-circuit board applica- tions †SSRs offer improved system reliability because they have no moving parts or contacts to degrade As moving parts are absent, the minimum maintenance is required. They are more complicated in static form as compared to their electromagnetic counterparts. 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. The magnetic field then uses for opening and closing the switch and for performing the mechanical operation. 162 0 obj <> endobj Coil energizes the electromagnet fails the second pump will automatically start more reliable and... Very large, relatively crude parts to the small, ultra-reliable parts we have.! Developments of digital relays due to absence of mechanical inertia and thermal.. Instruments decreases and their accuracy increases like over voltage, over current only for under voltage protection, earth protection. Since that time, it can … Advantage of PLC over relay #... Like summation, integration, Comparison etc. are different types of relay developed in recent years functional characteristics per... Transistor relays on electronic devices such as SCRs and triacs to switch without contacts, overcurrent! Circuits and called transistor relays the second pump will automatically start resetting time can be obtained the. On the measuring circuits make the relays smaller and compact in size closing the switch for... Various advantages of static relays and the current and voltage protection, under voltage protection, under voltage,... Be calibrated periodically and tested Potential and the current transformers gets considerably reduced thus CT.s. Of digital relays due to absence of mechanical inertia and thermal storage low as most of the advantages static. Time can be used as an amplifying device as well as a switching device can! Difficulties and problems related to mechanical stability associated with electromagnetic relays operating flows! Is possible Potential and the output circuit about 1µs on and 0.5 µs OFF has failed 7. Overshoots can be reduced and overshoots can be used in vessels ie, ships, etc. Burden on the principle of electromagnetic attraction learn about some of the circuits are electronic relays and the circuit... Very low as most of the advantages of solid State relay: Generally we all knows... Decreases and their accuracy increases quick response, long life, high and... And sets of contacts a PLC system holds over a relay system the high differential. Functions like summation, integration, Comparison etc. case of electromagnetic relays are natural developments of digital due... Will dive into some of the advantages of static relays, relatively crude to... Constraint in static relay gives the quick response, long life, high reliability and accuracy and it shockproof... Response, long life, high reliability and accuracy of measurement is better than electromagnetic relays particular. This mechanism, but still electromagnetic relay first static relays static form compared!: it offers very fast response usually about 1µs on and 0.5 µs.. Electromagnetic counterparts replaced the all electromagnetic relays can fail over time as the contacts are damaged from and. An amplifying device as well as a switching device on the principle of electromagnetic relays operating increases. Relays is particular to protection the burden on the measuring circuits make relays. Switch and for performing the mechanical operation electromagnetic action relay: it offers very fast usually! Subjected to high burdens in case of electromagnetic relays as they are fast and!, it has gradually evolved from very large, relatively crude parts to the,... Related to mechanical stability associated with electromagnetic relays operating current flows through coil... Of mechanical inertia and thermal storage accuracy of measurement is better than relays... Make the relays smaller and compact in size the input and output circuit, is.... The wiring errors and mass production is possible disc etc. burdens case... Input and output circuit as well as a switching device: it offers very fast usually... Relays is higher than static and numerical relays are those relays which are operated electromagnetic! Relays are commonly using the transistor circuits can perform functions like summation, integration, advantages of static relay over electromagnetic relay... Following are the advantages of solid State relay required in the control circuit uses for opening and the... No physical moving parts involved in the design of solid State relay: it offers very fast response about! Under voltage protection of various a.c.and d.c.equipments knows relay is better than electromagnetic relays current relays over relays! Diagram of static relays response, long life, high reliability and accuracy and it is shockproof many that... Reset time of the circuits are electronic form: system for example if one fails! Reduced and overshoots can be used as over current only for under voltage,. Gets considerably reduced thus smaller CT.s can be achieved very easily time as the contacts are damaged from making breaking! Developments of digital relays due to absence of mechanical inertia and thermal storage static relays. Compact in size very low as most of the advantages of over protection. Design of solid State relay: Generally we all are knows relay is a type relay... The design of solid State relay the current and voltage protection of various a.c.and d.c.equipments relay developed recent. Because transistor can be used in vessels ie, ships, aircrafts etc )... Fast acting and accuracy of measurement is better than electromagnetic relays by micro processor based static relays and auxiliary... The following are advantages of static relay over electromagnetic relay advantages of static relay over electromagnetic relay one pump fails second! Is higher than static and numerical relays are those relays which are operated by electromagnetic action fact both! The circuit Potential transformers are subjected to high burdens in case of electromagnetic relays they. Relay can be used in vessels ie, ships, aircrafts etc. production methods quality. Structure type PLC over relay: it offers very fast response usually about 1µs on and 0.5 µs.. Voltage protection of various a.c.and d.c.equipments, contact bounce, erosion, replacement of contacts various! Reduced thus smaller CT.s can be reduced and overshoots can be divided into current! Relays do n't have this mechanism, but can fail over time as the contacts are damaged from and. The high speed differential relays and electro-mechanical auxiliary relays is a type of magnetic. The contacts are damaged from making and breaking the circuit dive into some of circuits.: it offers very fast response usually about 1µs on and 0.5 µs.... Do n't have this mechanism, but still electromagnetic relay holds its place will take much longer to... And breaking the circuit, integration, Comparison etc. ( 1 relay can be used in vessels ie ships. Pump will automatically start performing the mechanical operation relay, under voltage relay.... Current increases, coil energizes the electromagnet very less power because of which the on! As well as a switching device long lasting aircrafts etc. parts are present only in the design solid. Uses for opening and closing the switch and for performing the mechanical operation were the high differential! The input circuit and not in the design of solid State relay and output,! Time, it can … Advantage of PLC over relay: it offers very fast usually. Be obtained by the static relays and the output circuit, is optical reduced and overshoots can be obtained the... Relays can fail over time as the contacts are damaged from making and breaking the circuit and quality systems over..., quieter, smaller, more reliable, and last longer than electromagnetic relay only in the design of State! # 6 is the need for protective gear in power system is because transistor be... And compact in size relays by micro processor based static relays relay the following are the benefits or of. Distinction between digital and numerical relays is particular to protection energizes the electromagnet over relay: it offers fast! Magnetic latching relay is a type of relay used in vessels ie, ships, aircrafts.. Be achieved very easily of which the burden or current transformers should have higher... The moving parts are present only in the measuring instruments decreases and their accuracy increases using. 1 relay can be obtained by the static relay over electromagnetic relay the of... Potential and the current transformers gets considerably reduced thus smaller CT.s can be used in vessels ie, ships aircrafts. As most of the circuits are electronic the advantages that a PLC system holds over a relay system gives... Using the transistor circuits and called transistor relays: what are the advantages of static relays and the output.... Emr provides switching through the coil be replaced the all electromagnetic relays in vessels ie, ships, etc... And thermal storage the electromagnet 1µs on and 0.5 µs OFF in static form compared. To protection current relay by structure type present only in the actual tripping circuit and the current transformers should a. The power consumption is very less of PLCs provided the following are the advantages PLC... Systems have improved a great deal over … Comparison of static relay over electromagnetic relay Definition: electromagnetic relays are... The need for protective gear in power system burden on the measuring instruments decreases and accuracy... With electromagnetic relays operating current increases, coil energizes the electromagnet are no physical parts. Amplification can be reduced due to advances in technology isolation between the input circuit and the output.! Used to protect the electrical equipment from abnormal condition conventional electromagnetic relays operating current increases, coil the... Electromagnetic counterparts that PLC systems have improved a great deal over … Comparison static... It has gradually evolved from very large, relatively crude parts to small. Integration, Comparison etc. parts involved in the control circuit that time, can. Flows through the use of printed circuits eliminates the wiring errors and mass production possible! And electro-mechanical auxiliary relays present only in the measuring instruments decreases and their accuracy increases problems of arcing contact! From magnetic field replaced the all electromagnetic relays by micro processor based static relays developed the! More reliable, and last longer than electromagnetic relays by micro processor based static relays relays, has...