He has more than 13 years experience in transmission & distribution-energy theft detection and maintenance electrical projects. Aim: To study the performance of an over voltage relay. STATIC RELAY. The constraint in static relay is limited function/features. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current Relay. It is generally set at 120% of Maximum Load Current. 4.21, the relay operates when the ratio V/I is less than a certain value and is, therefore, a minimum impedance relay. In a static over current relay, inverse time characteristics are obtained by . Relay setting, Over current relay, IDMT relay. The term ‘static’ implies that the relay has no moving mechanical parts in it. The output device is activated and gives the tripping command to the trip circuit. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. 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). Temperature dependence of static relays: The characteristics of semiconductor devices are affected by ambient temperature. The content is copyrighted to EEP and may not be reproduced on other websites. The pick-up of the relay is obtained by movement of the movable element in the relay. When currant in the circuit exceeds beyond the limit, the armature gets attracted by the magnetic force produced by the undesirable current. An op-amp and comparator is used to create a DC that rises when a trip point is reached. This relay has to be installed straight only and away from magnetic field. © 2003-2021 Chegg Inc. All rights reserved. In an over electric current relay, there would be essentially a electric current coil. It protects the equipment of the power system from the fault current. & Ii) Write The Purpose Of Start Of Conversion (S/C) And End Of Conversion (E/C) Signals In The Numerical Relay? 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 . Then auxiliary CT output is given to rectifier. 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. 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. 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. o A single relay can perform several functions like over current, under voltage, single phasing protection by incorporating respective functional blocks. Working Principle of Over Current Relay. It contains two relaying units, over current units and the other a directional unit. Over current relay with time-current characteristics:- 1. In case of electromagnetic directional overcurrent relays , discrimination is affected when voltage drops down to very low values under fault … The output unit energizes the trip coil only when relay operates. Compared to the Material is usually fed to them by a conveyor at a rate that provides maximum production capacity and prevents overloading. Thus, timing is very accurate even for currents as low as the pickup value. Static relays are sensitive to voltage transients which are caused by operation of breaker and isolator in the primary circuit of CTs and PTs. The value of preset current … c 25. Curve 1 represents a static instantaneous overcurrent relay which operates on the instantaneous current greater than or equal to the pickup level. Jignesh Parmar has completed M.Tech (Power System Control), B.E (Electrical). Question: I) Describe The Operation Of Time-dependent Static Over Current Relay With A Neat Diagram. High Range of Setting compared to electromechanical Relay, More Accurate compared to electromechanical Relay. Suppose We are to potect a 25 Amps line might be in a three phase system . It helps you. If people are interested I can go to the next portion . There is no intentional time delay applied. But 17. Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! (1 relay can be used as over current only for under voltage we use another relay). Ipu = 1.2 x Imax sec= 1.2 x 0.75 = 0.9 A Static Relay burden is less than Electromagnetic type of relays. There is only one current operated element in the relay, no voltage coil etc. The rectified output is supplied to a measuring unit comprising of comparators, level detectors, filters, logic circuits. 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. The rela y is suitab le f or current transformers with secondary rating of … The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. I) Describe The Operation Of Time-dependent Static Over Current Relay With A Neat Diagram. Static overload relay means for use in circuit breakers and having inverse time current characteristics 1967-08-29 Kelley et al. 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. Compared to the Electromechanical Relay, the Solid Static relay has longer life-span, decreased noise when operates and faster respond speed. The relay setting is 50% to 200% in steps of 25%. 13 An IDMT type over current relay is used to protect a feeder through 500/1A CT. This relay operate on the current setting. Hence, this relay has current setting range as … time current characteristics of static over current relay, components of instantaneous over current relay, instantaneous over current relays These ratings include voltage, ampere and interrupting rating. Depending on the time of operation the overcurrent relay is categorized into following types. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. Overcurrent Relay Objective Type Questions and answers; 31. Highly sophisticated isolation and filter circuits are required to be built into the relay design to take care of electromagnetic interference and transient switching disturbances in the power system. (1 relay can be used as over current relay, under voltage relay etc.) 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. are required to construct this protective relay.. 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. CPU 3. There are three fundamental systems of differential Thus it requires to serve the system voltage as well as the system current. 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 … Question testing the ability of students in applying the concepts I) Multiple choice questions 1. The term ‘static’ implies that the relay has no moving mechanical parts in it. An "Over Current Relay" is a type of protective relay which operates when the load current exceeds a preset value. A Protection relay which operates when the load current exceeds a preset value is called an overcurrent relay. In this the torque produced by a voltage element opposes the torque produced by a current element. are required to construct this protective relay. Characteristic variations with passage of time. 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. A relay that operates or picks up when it’s current exceeds a predetermined value (setting value) is called Overcurrent Relay. The output is actuated when the dynamic input (i.e., the relaying quantity) attains the threshold value. 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. 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. ii) Write the purpose of Start of Conversion (S/C) and End of Conversion (E/C) signals in the Numerical Relay? A static instantaneous overcurrent relay with reduced transient overreach is provided for use in protecting an a-c power line from overcurrents. Crushers come in several forms and are used to reduce the size of materials. The Solid State Relay (Static Relay) Overview. i) Describe the operation of time-dependent static over current relay with a neat diagram. Tell us what you're thinking... we care about your opinion! The current rating of the circuit in which relay is connected plays an important role in the operation of the relay. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. Delay in operation: Easily provided If it is require that relay should operate after some time then a timing circuit is used. The static relay only gives the response to the electrical signal. 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 … 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. 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. This is not possible in electromagnetic relays o Static relay is compact History of Relay:The static relay are next generation relays.The Solid Static relays was first introduced in 1960’s. A. Instantaneous over current relay. Directional Static over current relay • The directional relay is nothing but a differential power relay which operates when the power in the circuit flows in a particular direction. A curr… relay operates after some time only. Definite time relay is used in the trip circuit. A transistor amplifier . The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. 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. Working Principle of Over Current Relay . The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. Inverse time over current relay. B. The relay will only operate when this voltage to current ratio becomes less than its predetermined value. The output device activates the trip coil only when the relay operates. Curve 2 represents a static instantaneous overcurrent relay of the present invention which operates on the second current peak greater than or … eccentric cam. The output of CT and PT are not suitable for static components so they are brought down to suitable level by auxiliary CT and PT. D. A differentiating circuit many thanks from core of my heart and salute to you.. thank you. Solid state relays are fast becoming the better choice in many applications, especially throughout the telecommunication and microprocessor control industries. The relaying quantity such as voltage/current is rectified and measured. The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. 1 relay can perform only 1 function. The Solid Static relays use analogue electronic devices instead of magnetic coils and mechanical components to create the relay characteristics. 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. 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. The under-current The current relays for a.c. are combined with a special short-circuiting device type RTXK. : -ASOV) 2) Auxiliary D.C. supplies 110V 3) Time interval meter 4) Single pole variac 230V, 4A 5) Voltmeter (0 C. A transistor switch . 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. Functions: 1 relay can perform various functions. Static Relays Kongunadunadu College of Engineering and Technology Depar tment of EEE 16. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. Multiplexer and Analog to digital converter 5. There is no intentional time delay applied. This question hasn't been answered yet Ask an … The term ‘ static ’ implies that the relay has no … In many cases, EMRs are over-specified for current handling capability because no lower-current unit is available. Typical applications include shredding wood as well as crushing rock, coal, and other minerals. Over-current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. In a static relay, the measurement is performed by static councils. Study specialized technical articles and papers. Privacy With continual advancement in manufacturing technology, this gap has been reduced dramatically making the advantages of solid state technology accessible to a growing number of design engineers. The definite time relay operates after a defined minimum time. The relay is called percentage relay because the operating current required to trip can be expressed as a percentage of through current. So taking a 10% excess of that current we can take as preset value .Next matter is how we measure and compare . 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." 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. So the circuit breaker opens only after a over … 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. 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. In addition to the This relay has to be installed straight only and away from magnetic field. (1 relay can be used as over current relay, under voltage relay etc.) B. The relay type IRXm is a high-speed static over current rela y which measures one energizing current - the diff erential current I 0. 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. Terms 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. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay. 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). CT Ratio and Connection for Differential Relay This simple thumb rule is that the current transformers on any star winding should be connected in delta and the current … In some cases, relay burden is reduced, making for reduced CT/VT output requirements. The static relays have been designed to replace almost all the functions which were being achieved earlier by electromechanical relays. 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 . Low input signal levels: Ideal for Telecommunication or microprocessor control industries. In the event of an overload, a crusher can stall and jam, resulting in significant downtime to clean the material from the crusher and return it to operation. 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. In an over current relay or o/c relay the actuating quantity is only current. Serious over voltage is also caused by breaking of control circuit, relay contacts etc. Learn about power engineering and HV/MV/LV substations. The term "high The relay type IRXm is a high-speed static over current rela y which measures one energizing current - the diff erential current I 0 . In electrical systems, a static relay is a type of relay, an electrically operated switch, that has no moving parts. If people are interested then I can give you the next portion . When the quantity under measurement attains certain well-defined value, the output device is triggered and thereby the circuit breaker trip circuit is energized. User programming was restricted to the basic functions of adjustment of relay characteristic curves. : 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 … 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. 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. The over current relay operates and closes the circuit of definite time relay. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. An over current relay, having a current setting of 125% connected to a supply circuit through a current transformer of ratio 400/5. The high powered analog signals are stepped down with current tran… | When a relay operates to open its ÒaÓ contact, but does not reset, we say that it "drops out," and the largest value of the actuating quantity at which this occurs is called the "drop-out" value. The performance of static relay is better than electromagnetic relays as they are fast acting and accuracy of measurement is better than electromagnetic relay. Hence error is less. It protects the equipment of. 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. 3) Relay Pickup Current, Ipu: It is the current which when flows through the Relay Coil, the Relay Operates. Such directional relays are used when power can flow from both directions to The electro-mechanical relay operates when operating torque/fence exceeds the restraining torque/force. standard overcurrent relay, complete with taps and time dial, as found on a normal non-directional overcurrent relay. An over current relay having a current setting of 125% is connected to a supply circuit through a current transformer of ratio 400/5. Auxiliary voltage requirement for Relay Operation. 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. Highly reliable power supply circuits are required. An integrating circuit . 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. Therefore it can be viewed in simple terms as an analogue electronic replacement for electromechanical relays, with some additional flexibility in settings and some saving in space requirements. 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. The analog values are compared to settings made by the user via potentiometers in the relay, and in some case, taps on transformers. Memory 4. electrical engineering questions and answers. A simplified block diagram of a single input static relay is given in the above figure. A simplified block diagram of a single input static relay is given in the above figure. Over current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. E.g. 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. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current 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 . 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. 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. In some solid state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. Over-current protection protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc. In individual relays, there is a wide variation. Effect of environmental conditions like humidity, high ambient temperature, dust accumulation on PCB leading to tracking. Rectifier rectifies the relaying quantity i.e., the output from a CT or PT or a Transducer. In an over current relay, there would be essentially a current coil. Output module 6. The relay is simple, reliable and has small operating time, easy adjustment and good sensitivity. In a static relay, the measurement is performed by static councils. Definite time over current relay. 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. Apparatus Required:- 1) Static over voltage relay (Model No. 20% off code for Pro Plan: EEP2020. (1 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. 1 relay can perform only 1 function. 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 ……….. static relay block diagram ... or the amplitude follows the threshold condition.The input signals are derived from the primary power system through current and voltage transformers. Such voltage spikes of small duration can damage the semiconductor components and also cause mal operation of relays. They have electric motors sized to the capacity of the crusher. But there is always an inherent time delay which we cannot avoid practically. Draw and explain the block diagram of Static Instantaneous over Current Relay. The over-current or over- voltage relay operates (the armature picks up) when the supply to the coils reaches the set operating value. The term "instantaneous" means "having no intentional time delay" and is applied to relays that operate in a minimum time of approximately 0.1 second. He is member of Institution of Engineers (MIE), India. Hence, it can be said that the relay will only operate when the impedance of the line becomes less than predetermined impedance (voltage/current). Functions 1 relay can perform various functions. are required to construct this protective relay. The over-current or over- voltage relay operates (the armature picks up) when the supply to the coils reaches the set operating value. Digital input/Communication module Input Module The Power system operates with analog parameters. There is only one electric current operated element in the relay, no voltage coil etc. A definite time over-current (DTOC) relay is a relay that operates after a definite period of time once the current exceeds the pickup value.