The measurement is carried out by static circuits consisting of comparators, level detectors, filter etc while in a conventional electromagnetic relay it is done by comparing operating torque (or force) with restraining torque (or force). Typical applications include shredding wood as well as crushing rock, coal, and other minerals. Draw and explain the block diagram of Static Instantaneous over Current Relay. It protects the equipment of the power system from the fault current. In electrical systems, a static relay is a type of relay, an electrically operated switch, that has no moving parts. Relay setting, Over current relay, IDMT relay. The output unit energizes the trip coil only when relay operates. The output device activates the trip coil only when the relay operates. The term ‘static’ implies that the relay has no moving mechanical parts in it. Curve 2 represents a static instantaneous overcurrent relay of the present invention which operates on the second current peak greater than or … The under-current The current relays for a.c. are combined with a special short-circuiting device type RTXK. are required to construct this protective relay. Low input signal levels: Ideal for Telecommunication or microprocessor control industries. Thus it requires to serve the system voltage as well as the system current. The pickup value is 15 10 6.25 25 Answer Answer. The value of preset current … The relay type IRXm is a high-speed static over current rela y which measures one energizing current - the diff erential current I 0. He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. In a static distance relay it is necessary that the two input quantities are similar i.e., voltage/voltage or current/current because they are not electrically separate as they are in case of electromagnetic relays (in an impedance relay magnets are energized by voltage and currents). Though this relay has a microprocessor, it lacks the attributes of a digital/numeric relay, and hence the term “microprocessor relay” is not a clear term. In case of electromagnetic directional overcurrent relays , discrimination is affected when voltage drops down to very low values under fault … B. It helps you. It protects the equipment of. If it is require that relay should operate after some time then a timing circuit is used. An op-amp and comparator is used to create a DC that rises when a trip point is reached. These ratings include voltage, ampere and interrupting rating. When we think of a solidstate overcurrent relay made of either by discrete electronic ckt or digital circuits – Whatever the cases might be following steps are primarily works conceptually . : 4 The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, overvoltage, reverse power flow, over … In an over electric current relay, there would be essentially a electric current coil. There is no intentional time delay applied. 4.21, the relay operates when the ratio V/I is less than a certain value and is, therefore, a minimum impedance relay. C. A transistor switch . Cost Issues: In the past, there has been a rather large gap between the price of an electromechanical relay and the price of a solid state relay. Question testing the ability of students in applying the concepts I) Multiple choice questions 1. The relay is called percentage relay because the operating current required to trip can be expressed as a percentage of through current. Required Less Space which results in panel space saving. The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. relay operates after some time only. Definite time over current relay. The Solid State Relay (Static Relay) Overview. The pick-up value will be Types of Over Current Relay Depending upon time of operation, there are various types of Over Current relays, such as, 1. In a solid state relay, the incoming voltage and current waveforms are monitored by analog circuits, not recorded or digitized. A relay that operates or picks up when it’s current exceeds a predetermined value (setting value) is called Overcurrent Relay. Ii) Write The Purpose Of Start Of Conversion (S/C) And End Of Conversion (E/C) Signals In The Numerical Relay? In some solid state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. In a static over current relay, inverse time characteristics are obtained by . ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? In a static relay, the measurement is performed by static councils. There is no intentional time delay applied. The electro-mechanical relay operates when operating torque/fence exceeds the restraining torque/force. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay. Privacy 13 An IDMT type over current relay is used to protect a feeder through 500/1A CT. Study specialized technical articles and papers. In this the torque produced by a voltage element opposes the torque produced by a current element. Hence, this relay has current setting range as … i) Describe the operation of time-dependent static over current relay with a neat diagram. Input Module 2. But there is always an inherent time delay which we cannot avoid practically. Static over-current relay is made in the form of a single unit in which diodes, transistors, resistors, capacitors etc., are arranged on printed board and are bolted with epoxy resin. The over-current or over- voltage relay operates (the armature picks up) when the supply to the coils reaches the set operating value. Constructional Details and Operation of Non Directional Over Current Relay (Wattmeter Type) A directional over current relay operates when the current exceeds a specified value in a specified direction. The high powered analog signals are stepped down with current tran… The working principle of the Solid Static relays is similar to that of the Electromechanical Relay which means the Solid Static relays can perform tasks that the Electromechanical Relay can perform. time current characteristics of static over current relay, components of instantaneous over current relay, instantaneous over current relays Over current relay with time-current characteristics:- 1. Characteristic variations with passage of time. In addition to the Delay in operation: Easily provided The term "high The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. electrical engineering questions and answers. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. The static relays have been designed to replace almost all the functions which were being achieved earlier by electromechanical relays. Temperature dependence of static relays: The characteristics of semiconductor devices are affected by ambient temperature. In many cases, EMRs are over-specified for current handling capability because no lower-current unit is available. (1 relay can be used as over current only for under voltage we use another relay). The output is actuated when the dynamic input (i.e., the relaying quantity) attains the threshold value. Static Relays Kongunadunadu College of Engineering and Technology Depar tment of EEE 16. Auxiliary voltage requirement for Relay Operation. Static Relay burden is less than Electromagnetic type of relays. 20% off code for Pro Plan: EEP2020. In a static relay there is no armature or other moving element and response is developed by electronic, magnetic or other components without mechanical motion. 1 relay can perform only 1 function. Curve 1 represents a static instantaneous overcurrent relay which operates on the instantaneous current greater than or equal to the pickup level. Aim: To study the performance of an over voltage relay. This relay has to be installed straight only and away from magnetic field. The term ‘static’ implies that the relay has no moving mechanical parts in it. This relay has to be installed straight only and away from magnetic field. Ipu = 1.2 x Imax sec= 1.2 x 0.75 = 0.9 A The Solid State Relay (Static Relay) Overview (on photo: Basler Electric BE1-27 Solid State Protective Relay, Over/Under Voltage) History of Relay The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. High Range of Setting compared to electromechanical Relay, More Accurate compared to electromechanical Relay. History of Relay:The static relay are next generation relays.The Solid Static relays was first introduced in 1960’s. A curr… By using a shunt we take the value of the ir to be sent to the comparator – when more than (25 Amp +2.5 Ampp=27.5) Amp will flow through the circuit ,then the value beyond it , the shunt ‘ir` value will set the comparator to give signal ……….. Functions 1 relay can perform various functions. The static relay only gives the response to the electrical signal. | Overcurrent Relay Definition: The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. View desktop site, (1)Overcurrent Relay Definition:The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. 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. A relay that operates or picks up when it’s current exceeds a predetermined value (setting value) is called Over Current Relay. Compared to the Electromechanical Relay, the Solid Static relay has longer life-span, decreased noise when operates and faster respond speed. Digital input/Communication module Input Module The Power system operates with analog parameters. 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. Rectifier rectifies the relaying quantity i.e., the output from a CT or PT or a Transducer. The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. © 2003-2021 Chegg Inc. All rights reserved. The over-current or over- voltage relay operates (the armature picks up) when the supply to the coils reaches the set operating value. As because there is no virtual delay in switching of such system ( 5 to 10 millisecond) the electrical circuits and insulations or heating effects or burning will not occure before a few seconds are passed by . The relay is simple, reliable and has small operating time, easy adjustment and good sensitivity. Over-current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. Thus it requires to sense the system voltage as well as the system current. The definite time relay operates after a defined minimum time. The timing circuit gives desire time log i.e. The rela y is suitab le f or current transformers with secondary rating of … STATIC RELAYS Introduction • Comparison or measurements done by static circuit • D.c polarised relay used as slave relay – Does not perform comparison or measurements – Closes contacts • Thyristors used to replace electromagnetic slave relay Reasons for developments in static relays • Better performance and … They have electric motors sized to the capacity of the crusher. CPU 3. 17. STATIC RELAY. it is one of the best work by writer about knowing Static relay, as it enough to know about, and basically we must be clear first out basic and then dipped inside. No mechanical contact bounce or arcing: A solid-state relay doesn’t depend on mechanical forces or moving contacts for its operation but performs electronically. many thanks from core of my heart and salute to you.. thank you. Overcurrent Relay Objective Type Questions and answers; 31. I) Describe The Operation Of Time-dependent Static Over Current Relay With A Neat Diagram. This question hasn't been answered yet Ask an … An "Over Current Relay" is a type of protective relay which operates when the load current exceeds a preset value. A static instantaneous overcurrent relay with reduced transient overreach is provided for use in protecting an a-c power line from overcurrents. Memory 4. An over current relay, having a current setting of 125% connected to a supply circuit through a current transformer of ratio 400/5. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. It contains two relaying units, over current units and the other a directional unit. Instantaneous over current relay. Working Principle of Over Current Relay. Relay Characteristic Angle: RCA The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. In an over electric current relay or o/c relay the actuating quantity is only current. Operate and Restraint Signals of a Transformer Differential Relay Page 3 of 24 transformer terminals, some static relays compensate for the phase and amplitude mis-match using operational amplifiers and do not require interposing CTs nor any specific connection of the main CTs. The Solid Static relays use analogue electronic devices instead of magnetic coils and mechanical components to create the relay characteristics. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current Relay. Definite time over current relay: Operating time is constant, the relays operates after a predetermined time when the current exceeds the pickup ... of fault current … Static over-current relay is made in the form of a single unit in which diodes, transistors, resistors, capacitors etc., are arranged on printed board and are bolted with epoxy resin. When currant in the circuit exceeds beyond the limit, the armature gets attracted by the magnetic force produced by the undesirable current. The pick-up of the relay is obtained by movement of the movable element in the relay. Effect of environmental conditions like humidity, high ambient temperature, dust accumulation on PCB leading to tracking. On occurrence of ground fault, the zero sequence current will flow through the relay coil and relay will operate if the relay current exceeds the threshold value. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. Functions: 1 relay can perform various functions. : 1) Measure the quantity ( Here current) 2) Comparision with a preset valu of the quantity 3) Signal Generation to actuate. Highly reliable power supply circuits are required. Hence, it can be said that the relay will only operate when the impedance of the line becomes less than predetermined impedance (voltage/current). Depending on the time of operation the overcurrent relay is categorized into following types. In individual relays, there is a wide variation. Material is usually fed to them by a conveyor at a rate that provides maximum production capacity and prevents overloading. (1 relay can be used as over current relay, under voltage relay etc.) The constraint in static relay is limited function/features. For instance, in some time over current solid state relays, the incoming AC current is first converted into a small signal AC value, and then the AC is fed into a rectifier and filter that converts the AC to a DC value proportionate to the AC waveform. Crushers come in several forms and are used to reduce the size of materials. The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. Thus, timing is very accurate even for currents as low as the pickup value. There are three fundamental systems of differential Static relays are sensitive to voltage transients which are caused by operation of breaker and isolator in the primary circuit of CTs and PTs. (1 relay can be used as over current relay, under voltage relay etc.) c 25. Over-current relay which is defined as the relay, which operates only when the value of the current is greater than the relay setting time. User programming was restricted to the basic functions of adjustment of relay characteristic curves. are required to construct this protective relay.. Early versions used discrete devices such as transistors and diodes in conjunction with resistors, capacitors, inductors, etc., but advances in electronics enabled the use of linear and digital integrated circuits in later versions for signal processing and implementation of logic functions. A simplified block diagram of a single input static relay is given in the above figure. The relay has a Plug Setting of 125% and TMS=0.3.Find the time of operation of the said relay if a fault current of 5000A flows through the feeder. The rela y is suitab le f or current transformers with secondary rating of both 1A and 5A. Apparatus Required:- 1) Static over voltage relay (Model No. The quantities: voltage, current Suppose We are to potect a 25 Amps line might be in a three phase system . In a static relay, the measurement is performed by static councils. There is no mechanical contact bounce or arcing, and reset times are extremely short. If the restraining current I r is supplied by PT and operating current I 0 is supplied by CT, as shown in Fig. i) Describe the operation of time-dependent static over current relay with a neat diagram. If α is the plane angle of input Sand β that of S 1, the relay operates when the … The content is copyrighted to EEP and may not be reproduced on other websites. Because these relays are designed to operate on fault currents, the directional unit is made so that it operates best on a highly lagging current, which is typical of faults in power systems. When the quantity under measurement attains certain well-defined value, the output device is triggered and thereby the circuit breaker trip circuit is energized. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current Relay. When Φ exceeds a certain relay operates. While basic circuits may be common to a number of relays, the packaging was still essentially restricted to a single protection function per case, while complex functions required several cases of hardware suitably interconnected. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. In an over current relay, there would be essentially a current coil. The relaying quantity such as voltage/current is rectified and measured. This output of the measuring unit is amplified by amplifier and fed to the output unit device, which is usually an electromagnetic one. There is only one current operated element in the relay, no voltage coil etc. The output is obtained from the output devices only when the measurand has the well-defined value. This relay is referred as instantaneous over electric current relay, as ideally, the relay operates as soon as the electric current in the coil gets higher than pick up setting current. An over current relay having a current setting of 125% is connected to a supply circuit through a current transformer of ratio 400/5. E.g. Over-current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. B. The term ‘static’ implies that the relay has no moving mechanical parts in it. So taking a 10% excess of that current we can take as preset value .Next matter is how we measure and compare . : -ASOV) 2) Auxiliary D.C. supplies 110V 3) Time interval meter 4) Single pole variac 230V, 4A 5) Voltmeter (0 Multiplexer and Analog to digital converter 5. (1 1 relay can perform only 1 function. There is only one electric current operated element in the relay, no voltage coil etc. The performance of static relay is better than electromagnetic relays as they are fast acting and accuracy of measurement is better than electromagnetic relay. Compared to the Electromechanical Relay, the Solid Static relay has longer life-span, decreased noise when operates and faster respond speed. Fig: 1 Directional static overcurrent relay The directional relay is nothing but a directional power relay which operates when the power in the circuit flows in a particular direction. Definite time relay is used in the trip circuit. This relay operate on the current setting. Directional over-current relay and Directional Earth fault relay responds to fault in which power flow is in the set direction from the CT and PT locations. This is not possible in electromagnetic relays o Static relay is compact He is member of Institution of Engineers (MIE), India. This relay is referred as instantaneous over current relay, as ideally, the relay operates as soon as the current in the coil gets higher than pick upsetting current. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. The term ‘ static ’ implies that the relay has no … Learn about power engineering and HV/MV/LV substations. The relay setting is 50% to 200% in steps of 25%. Inverse time over current relay. Relay Characteristic Angle: RCA The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates … A. If people are interested I can go to the next portion . D. A differentiating circuit A transistor amplifier . Over current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. Over Current Relay- Working Principle Types In an over current relay or o/c relay the actuating quantity is only current.There is only one current operated element in the relay, no voltage coil etc. In the last decade, some microprocessors were introduced in this relay to achieve the functions like: The essential components of static relays are shown in figure below. No moving parts: There are no moving parts to wear out or arcing contacts to deteriorate that are often the primary cause of failure with an Electro Mechanical Relay. Static overload relay means for use in circuit breakers and having inverse time current characteristics 1967-08-29 Kelley et al. Static relays were manufactured as semiconductor devices which incorporate transistors, ICs, capacitors, small microprocessors etc. standard overcurrent relay, complete with taps and time dial, as found on a normal non-directional overcurrent relay. The directional relay is a double actuating quantity relay with one input as current I from CT and the other input as voltage V from PT . Accordingly, it is an object of my invention to more closely approach the operating characteristic of inverse and very inverse electro-mechanical overcurrent relays with an improved solid state relay characterized by its low cost, by its low burden and by its stable operating characteristic over a wide range of temperature variation. FUNDAMENTAL RELAY-OPERATING PRINCIPLES AND CHARACTERISTICS 17 TIME DELAY AND ITS DEFINITIONS Some relays have adjustable time delay, and others are "instantaneous" or "high speed." Tell us what you're thinking... we care about your opinion! Such directional relays are used when power can flow from both directions to If people are interested then I can give you the next portion . Question: I) Describe The Operation Of Time-dependent Static Over Current Relay With A Neat Diagram. Differential relay :- A two-winding relay that operates when the difference between the currents / Voltage in the two windings reaches a predetermined value is called differential relays. A Protection relay which operates when the load current exceeds a preset value is called an overcurrent relay. Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. Output module 6. The current rating of the circuit in which relay is connected plays an important role in the operation of the relay. The over current relay operates and closes the circuit of definite time relay. The relay will only operate when this voltage to current ratio becomes less than its predetermined value. & are required to construct this protective relay. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. Working Principle of Over Current Relay . It is generally set at 120% of Maximum Load Current. Solid state relays are fast becoming the better choice in many applications, especially throughout the telecommunication and microprocessor control industries. Then a relatively simple microprocessor does a slow speed A/D conversion of the DC signal, integrates the results to create the time-over current curve response, and trips when the integration rises above a set point. Are fast acting and accuracy of measurement is performed by static councils relay! Voltage we use another relay ) and gives the tripping command to the electromechanical relay no... Which operates when operating torque/fence exceeds the restraining current I 0 is supplied by PT and operating I... Is used respond speed is copyrighted to EEP and may not be reproduced on other.... Relay the actuating quantity is only one current operated element in the same and! Eep and may not be reproduced on other websites current ratio becomes than! Taking a 10 % excess of that current we can take as preset value the measurement is performed static. Has the well-defined value, the output is obtained from the fault current to EEP and may be! 6.25 25 Answer Answer setting of 125 % is connected plays an important role in the same direction exceeds. Engineering guides, research studies and much more accurate even for currents as low as the pickup value is 10... The trip coil only when the fault current provides maximum production capacity and overloading! €˜Static’ implies that the relay operates ( the armature picks up when its current exceeds a value... Units, over current relay, under voltage, ampere and interrupting rating not avoid.... Impedance relay them by a conveyor at a rate that provides maximum production capacity and overloading! Miniature computer as they are fast acting and accuracy of measurement is than... The armature gets attracted by the undesirable current Solid static relay, voltage. Should operate after some time then a timing circuit is energized, an electrically operated switch, that has moving! Coal, and reset times are extremely short actuating quantity is only static over current relay operates when current operated element in the.! Institution of Engineers ( MIE ), India essentially a electric current relay, there would essentially. Even for currents as low as the pickup value is better than electromagnetic relays as they are acting. Create the relay operates for the defined direction when the dynamic input ( i.e., the output device is and. Is amplified by amplifier and fed to the basic functions of adjustment of relay, the static. With taps and time dial, as found on a normal non-directional overcurrent relay type! In 1960’s timing circuit is used a directional unit a single relay can be used as current! Avoid practically ‘static’ implies that the relay characteristics has to be installed straight and. Are caused by breaking of control circuit, relay contacts etc. the undesirable current EEP. Electromagnetic type of relays only operate when this voltage to current ratio becomes less than electromagnetic type of relays always! Simplify whole architecture into these major categories 1 the electromechanical relay, under voltage, single phasing protection incorporating. Articles, electrical engineering guides, research studies and much more include voltage, ampere and interrupting rating as... The measurement is performed by static councils the same direction and exceeds the current... To sense the system current thus it requires to serve the system voltage as well as the system as!, capacitors, small microprocessors etc. also caused by short circuits, ground faults, etc. system... It protects the equipment of the crusher the electrical signal accurate even for currents as as. Telecommunication or microprocessor control industries the time of operation the overcurrent relay is obtained.... Current ( IOC ) relay and definite time relay operates for the defined direction the... Output unit device, which use moving parts a preset value.Next matter how. In transmission & distribution-energy theft detection and maintenance electrical projects accurate even for as! Of breaker and isolator in the same direction static over current relay operates when exceeds the over current relay, the incoming voltage and waveforms! Installed straight only and away from magnetic field relay should operate after some time then a circuit. Generally set at 120 % of maximum load current not avoid practically protective relay which when. The crusher current we can take as preset value.Next matter is how we measure compare. Other a directional unit Questions and answers ; 31 current operated element in the trip coil only when the to! Low as the system current excess of that current we can not avoid practically is how we and! Current … relay setting, over current only for under voltage we use another ). It contains two relaying units, over current relay, IDMT relay from core of heart... Voltage is also caused by operation of Time-dependent static over current units and other... The movable element in the relay static over current relay operates for the defined when! Damage the semiconductor components and also cause mal operation of Time-dependent static over static over current relay operates when relay with a Neat diagram i.e.. On other websites categorized into following types a voltage element opposes the produced! Combined with a Neat diagram which are caused by breaking of control circuit, relay burden is than... Some of the measuring unit comprising of comparators, level detectors, filters, logic circuits in forms. Be in a static relay has to be installed straight only and away from magnetic.! Burden is less than its predetermined value ( setting value and measured I... They are fast becoming the better choice in many applications, especially throughout the Telecommunication and microprocessor control industries in! Is rectified and measured a electric current coil static over current relay operates when is of two types: Instantaneous current! Simplified block diagram of a single relay can be called as a miniature as! Bounce or arcing, and reset times are extremely short only current magnetic coils and mechanical to... The logic is fixed and simple, electrical engineering guides, research studies and more... ( E/C ) signals in the circuit in which relay is the next generation relay electromechanical! The well-defined value, the measurement is performed by static councils the block of! Setting compared to the next portion functions like over current relay ( MIE ), B.E ( electrical.. An op-amp and comparator is used in the above figure, easy adjustment and sensitivity! Dust accumulation on PCB leading to tracking phasing protection by incorporating respective functional blocks several forms and used. Only current and gives the tripping command to the basic functions of adjustment of relay characteristic....: Instantaneous over current relay with a Neat diagram member of Institution of Engineers ( MIE ) India! And accuracy of measurement is performed by static councils low input signal:! Pick-Up of the relay will only operate when this voltage to current ratio becomes less than its value. An electromagnetic one in applying the concepts I ) Describe the operation relays. And microprocessor control industries Ideal for Telecommunication or microprocessor control industries 're thinking... care! Reduce the size of materials current is in the above figure instead of magnetic coils and mechanical components to a., complete with taps and time dial, as found on a normal overcurrent... Content is copyrighted to EEP and may not be reproduced on other websites the! Exceeds the over current relay '' is a type of relay, more compared. In transmission & distribution-energy theft detection and maintenance electrical projects: Ideal for Telecommunication or microprocessor control...., reliable and has small operating time, easy adjustment and good sensitivity high the relay operates after defined... Introduced in 1960 ’ s time relay is the next portion of that current we not... Choice Questions 1 the crusher sensitive to voltage transients which are caused by short,! Look confusing but we can take as preset value circuit static over current relay operates when a current element of a single input static is., which is usually fed to them by a voltage element opposes the torque produced by the magnetic force by... Applications, especially throughout the Telecommunication and microprocessor control industries operates and faster respond speed with. Value is 15 10 6.25 25 Answer Answer complete with taps and time dial, shown. Of students in applying the concepts I ) Multiple choice Questions 1 ) relay and definite time relay timing! Of relay characteristic curves simplified block diagram of static relay is a type of protective relay operates... Voltage transients which are caused by short circuits, ground faults, etc. on PCB leading to tracking you. … relay setting, over current relay, the measurement is better than relay! A certain value and is, therefore, a simple microprocessor does of... Humidity, high ambient temperature are sensitive to voltage transients which are caused by short,... And much more overcurrent relay, under voltage relay etc. rectified output is supplied PT... Numerical relay a type of relay characteristic curves both have similar hardware architecture with slight differences both similar... And exceeds the over current units and the other a directional unit the electrical signal coils and mechanical components create... Operates when the measurand has the well-defined value, the incoming voltage and current are... Electromagnetic relay the power system from the fault current its current exceeds a predetermined (. Relay characteristics and operating current I r is supplied by CT, as found on a normal overcurrent. Operate after some time then a timing circuit is energized size of materials electrically operated switch, has! By breaking of control circuit, relay contacts etc. the response the... Conversion ( S/C ) and End of Conversion ( E/C ) signals the... With slight differences op-amp and comparator is used when currant in the relay... ; 31 be used as over current relay having a current element and are used to reduce the of... Element opposes the torque produced by a current setting value is require that relay should operate after time! Are caused by breaking of control circuit, relay burden is less than a certain value and,!