Content Guidelines 2. In addition to these the other types of static relays are: Hall effect relays; Inverse time overcurrent relay; Directional static overcurrent relay; Static differential relay; … The restraining current so obtained is rectified and partially smoothened by the short-circuit effect of the rectifier on the control winding and also due to the short- circuited coupling winding. I1 = I1max sin ωt and I2 = I2max sin (ωt – α) …(4.2), Flux through crystals I and II will be ɸ1 α I1 and ɸ2 α I2, and current through the crystals will be I’1 [α (dI2/dt)] and I2 [α (dI1/dt)] …(4.3), Two crystals I and II are connected in such a way that their output voltages are in opposition. Two basic arrangements are shown in Fig. Transistor relays are the most widely used static relays. The basic R-C circuit can also be arranged in several series-parallel combinations to have different values of TC. Electromagnetic Relay. In an actual relay, Ithreshold can be adjusted. Types of Relay Elements: The Important Types of Relay Elements or also called Electromagnetic Types are 1.Induction Disc Relay The shaded pole type gives the most effective form of an electromagnet since it has the following: Higher torque/VA. Where, IS is the magnitude of set current, ɸ is the phase angle between V and I and θ is characteristic angle. If you have a dynamic IP address or multiple static IPs, this isn't as much of an issue. = KH ɸmax Imax [cos α – cos (2ωt – α)] … (4.1). Gauss Effect Relays. When this happens a voltage is induced in the output winding and the relay gets energised. When the voltage on the timing capacitor VC attains the threshold value of the level detector II, tripping occurs. The transductor relays are mechanically very simple and are quite reliable. They are more complicated in static form as compared to their electromagnetic counterparts. Relay is a statically typed and type-inferred language, allowing programs to be fully typed while requiring just a few explicit type annotations. In the former arrangement two ac quantities under comparison are rectified and applied in opposition in the control grid circuit of an electronic tube and the operation occurs when one quantity exceeds the other by an amount depending on the bias. The current from the line CT is reduced to 1/1000th by an auxiliary CT, the auxiliary CT has taps on the primary for selecting the desired pick-up and current range and its rectified output is supplied to level detector I (overload level detector) and an R-C timing circuit. In both types of relays, the desired characteristic is that the operating time (t) ... E. W. Kimbark disclosed a static overcurrent relay including a non-linear voltage modifying circuit using zener diodes or the like for modifying the DC voltage applied to a series RC circuit as a function of the amount of overcurrent. Hence less panel space is required in case of static overcurrent relays. Overcurrent relays are also employed in conjunction with distance relays to provide backup protection. History of Relay. POLYTECHNIC MAYURBHANJ, TIKARPADA 2. Time delay relays 2. By varying values of R and C the time can be varied without difficulties. In the latter arrangement one ac quantity is connected to the control grid and the other to the screen grid of the electronic tube. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. It incorporates the latest developments in semiconductor technology and its applications to power system protection. Transductor (Magnetic Amplifier Relays) 3. 4.11 (a) is deleted. The operating winding is wound in such a way that the ampere-tums so produced oppose the restraining ampere-turns in one limb and strengthen them in the other. When the input to measuring unit is less than the threshold value, the output of the level detector is zero. Get ideas for your own presentations. With n = 1; It = K. The characteristic becomes inverse characteristic. The dynamic assignment is performed by the inverse ARP feature. Share yours for free! The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. Static overcurrent 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. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. The protective relays are either single actuating quantity relays such as overcurrent, under-voltage, earth fault relay or double actuating quantity relays such as distance relays, differential relays. The fact that a transistor can be employed both as an amplifying device and a switching device makes it suitable for achieving any functional characteristic. With higher value of n, the characteristic becomes more and more inverse. Static relay 1. CPU 3. Transistor Relays 5. 4.2 (b)]. The control windings are energized with dc and the operating windings with ac. The term ‘static’ implies that the relay has no moving mechanical parts in it. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Transistor which acts like a triode can overcome most of the limitations posed by the electronic valves and thus has made possible to develop the electronic relays more commonly known as static relays. Plagiarism Prevention 5. The same construction may be used for under-voltage, overvoltage or earth fault relays too. Where, VT is the threshold value of the level detector II. This phenomenon is called the magneto resistivity or Gauss effect. each type of relay. Nonlinear resistors are used to have other time characteristics. Types of solid state relays include reed relay coupled SSR, … After operation of the measuring unit, the output is amplified by the amplifier. Fitzgerald presented a carrier current pilot relaying scheme for the protection of transmission lines in 1928. STATIC RELAY NAME- ROHIT KUMAR MARNDI REGD NO- F15152002039 BRANCH- ELECTRICAL ENGINEERING YEAR:- 2015-18 GOVT. The component of the static relay is shown in the figure below. 2. Input Module 2. Digital / Numerical relays They can also be classified as: 1. This relay has to be installed straight only and away from magnetic field. Address assignment to DLCI is achieved by dynamic or static address assignment. Magneto resistors are sensitive to the magnetic field strength and not to the rate of variation. The block diagram of a static overcurrent time relay is shown in Fig. Report a Violation 11. Because reverse ARP is enabled by default, no additional commands are required. The general equation for time characteristic is given as –. Electrical Engineering, Devices, Relays, Static Relays, Static Overcurrent Relays and Its Types. The comparator used in directional overcurrent relay may be Hall Effect generator; Rectifier bridge comparator; Instantaneous coincidence comparator or integrating coincidence phase comparator. The magnitude of this voltage is proportional to the product of strength of the magnetic field and current. Instantaneous overcurrent relays are also useful in other protective relay systems. The measuring unit determines whether the quantity has attained the threshold value (set value) or not. Inverse-time relays are used where the source impedance is much smaller than the line impedance. The output of this summation CT is fed to an auxiliary CT, whose output is rectified, smoothened and supplied to the measuring unit (level detector). A telephone type relay can be directly operated from the Hall voltage. Disclaimer 8. Therefore solid state relays are also called as static relays. On the other hand if it is used as a phase comparator to achieve higher sensitivity it will depend on an external ac supply which is sometimes difficult to arrange. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. Figure 4.15 represents the static directional relay with two inputs (V and I). Privacy Policy 9. Directional relay senses direction of power flow by means of phase angle between V and I. Static relays 3. 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. Indium antimonite and indium arsenide are more sensitive in comparison to bismuth or mumetal. Report a Violation 11. Subsequently a series of electronic circuits for most of the common types of protective gear relays were developed. Transistor Relays 5. Functions: 1 relay can perform various functions. Account Disable 12. If you are running a relay from home and have one static IP, you may want to consider running a bridge instead so that your non-Tor traffic doesn't get blocked as though it's coming from Tor. The term previously applied to this type of relay was semistatic relay. INTRODUCTION In a protection relay, the term 'static' refers to the absence of moving parts to create the relay characteristic. So the output voltage will be –, VH α (V1 – V2) α {[I1(dI2/dt)] – [I2 (dI1/dt)]}, α I1max sin ωt x I2max ω cos (ωt – α) – I2max sin (ωt – α). This effect depends upon the ratio of depth to width and increases with the increase in this ratio. Such a characteristic is known as definite time characteristic of overcurrent relay. 4.2 (a)] and the other makes use of a phase comparator [Fig. Relay will operate when IS < I cos(ɸ – θ). Hall device is much simpler in construction and does not require auxiliary dc supply while the transistorized circuits require about 10V dc supply. Definite time overcurrent relays are used for wide variations of systems conditions, as backup relays for differential and distance protection, and differential protection of transformers to avoid mal-operation during magnetization inrush currents. Then it suddenly increases and becomes very large for a small value of operating current. Assuming equality of restraining and operating turns, and neglecting the finiteness of permeability, the operating current would drive out of saturation, the limb in which operating current opposes the restraining ampere-turns, when the peak value of the operating current exceeds the magnitude of restraining current. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Copyright 10. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Rectifier Bridge Relays 4. Uploader Agreement. However, static overcurrent relays offer several advantages over the electromagnetic form: 1. ered to a load. These latter types of applications are described in detail in “Phase Control Using Thyristors” (AN1003). In instantaneous overcurrent relays, the time delay circuit shown in Fig. The directional overcurrent relay can be made either instantaneous or time-lag type. A phase shifter is included in the voltage input circuit, whose output is fed to the phase comparator; so that the output from phase comparator under phase faults/earth fault condition is maximum. Types Of Relay, Terminals Of Relay, Application Of Relay, Control Input or Coil Terminals, COM or Common Terminal, NO Terminal, NC Terminal, Poles & Throw, Operation Of Relay, SPST, SPDT, DPST, DPDT Relay, Forms Of Relay, “Form A, Form B, Form C & Form D” Relay, Based On Operation Principles, EMR (Electromechanical Relay), SSR (Solid State Relay), Hybrid … The first static relays developed were the high speed differential relays and the distance relays. Protective Relays 3. Prohibited Content 3. The characteristic becomes a straight line parallel to current axis for n = 0. 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. [gravityform id="1" title="false" description="false" ajax="true"]. The transistor circuits cannot only perform the essential functions of a relay (such as comparison of inputs, summation and integrating them) but they also provide necessary flexibility to suit the various relay requirements. The inputs are supplied to the phase comparator. View Static Relays PPTs online, safely and virus-free! Static relay without output contacts – A static relay having no contact in its output circuit (s). This interaction costs printed-circuit board real estate, typically 0.2 inches (5 mm) on all sides of an EMR, a hidden cost of using an EMR solution. 2. In case of static overcurrent relays instantaneous reset is possible. Gauss Effect Relays. The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. 4.9. A new chapter on Microprocessor Applications to Protection has been added. where M is time-multiple setting, I is multiple of tap current; Ip is the multiple of tap current at which pick-up occurs, n is characteristic index of relay, t is time of operation in seconds and K is design constant of the relay. The device thus acts as a pure phase comparator. Types of Relays. 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. The effect of this is to drive both the limbs on which the operating winding is wound into saturation. Cisco routers support all network layer protocols using Frame Relay, such as IPv4, IPv6, IPX and AppleTalk. 4.5 (a) and 4.5 (b) current of constant magnitude flows in the collector circuit only when the input ac quantities are simultaneously positive; a relay in the collector circuit will pick up when the overlap angle exceeds a certain value, i.e., when the mean dc level in the collector circuit exceeds the relay pick-up as a consequence of phase coincidence. In conventional electromagnetic relays, n may vary between 2 and 8. The RSR-72 type relay for re-start and reacceleration is deigned to perform the automatic motor restarting, after control and protection device opening, as a consequence of a momentary line voltage interruption or drop-out. Actually, a relay is nothing but a combination of one or more open or closed contacts. Thus directional relay is a double actuating quantity relay with one input as current I from CT and the other input V from PT. The voltage so developed is very small and it is difficult to detect it. A single coil which permits use … Each group may comprise only one winding but if there is more than one winding in a group all those windings are magnetically linked. The book is a thoroughly revised and updated second edition of a successful text. Electronic Relays 2. The performance of CT under short-circuit condition is also improved. Static AC Switches Normally Open Circuit The circuit shown in Figure AN1007.1 provides random (any-where in half-cycle), fast turn-on (<10 µs) of AC power loads and is ideal for applications with a high-duty cycle. The output of phase comparator is fed to the level detector. On the other hand the windings of the different groups are not magnetically linked. Low CT burden – The VA consumption of static overcurrent relays is quite low (7 mVA to 100 mVA) as compared with that of electromagnetic relays (1VA to 3VA) so that smaller CTs are required. The double frequency term can be eliminated by cross-connecting two Hall generators, as illustrated in Fig. A transductor comprises essentially a magnetic core carrying two groups of windings usually known as operating windings and control windings. However, it takes up more room and is slower than an SSR. If one ac voltage V1 develops a magnetic field through the crystal in the form of disc having large diameter and another ac voltage V2 sends a current radially through the disc, then the current will be proportional to V1V2 cos θ where θ is the angle between the two voltages V1 and V2 i.e., current is maximum when the two voltages are in phase and zero when they are in quadrature. As there is no moving part, operating time of the order of 0.02 s (1 cycle) can be achieved. 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 ”. Staticrelays Components of static relays Block diagram of static relays Types of static relays Prepared By Mr.K.Jawahar, M.E., Assistant Professor Department of EEE Static Relays Kongunadunadu College of Engineering and Technology Depar tment of EEE An electromechanical relay is robust and versatile. Fault current level detectors are termed overcurrent relays. Such relays became popular because of development of semiconductor diodes. The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. That is why a heavy duty telephone type relay is employed with large setting. Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. But its use in static relays is limited because of high cost of crystal. This is because the induction disc characteristics of the overcurrent relays (inverse characteristics) are not amenable to simple mathematical analysis. The operation depends on the difference of the average rectified voltage (V1-V2).Here the rectifiers are not protected against higher currents. Inspite of the advantages of fast operation, low maintenance, low burden on CTs and PTs, absence of mechanical inertia and bouncing contacts, they suffered inherently from the requirements of ht supply, short life, large power consumption, It supply for the heater elements. Fault current level detectors are termed overcurrent relays. Response of Tower-Like Structures to Wind Loading | Wind Engineering, Unconventional Machining Processes: AJM, EBM, LBM & PAM | Manufacturing, Material Properties: Alloying, Heat Treatment, Mechanical Working and Recrystallization, Design of Gating System | Casting | Manufacturing Science, Forming Process: Forming Operations of Materials | Manufacturing Science, Generative Manufacturing Process and its Types | Manufacturing Science. Static relays are classified according to the type of the measuring unit or comparator as follows: 1. When a conductor is kept perpendicular to the magnetic field and a direct current is passed through it, it results in an electric field perpendicular to the directions of both the magnetic field and current with a magnitude proportional to the product of the magnetic field strength and current. Due to smoothening and rectifying a signal, a delay is introduced because of the time constant of the smoothening circuit and hence the relays are slow in operation and, therefore, are discarded for protection applications. Smoothening circuit and filters are introduced in the output of the bridge rectifier. The components used were electronic valves for measuring unit. Such a circuit would need only one level detector. The electrical protective relay can be broad, classified into two categories (i) Electromagnetic Relay and (ii) Static Relay. 1. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. Digital input/Communication module Input Module The Power system operates with analog parameters. Electromagnetic relays 2. It will take much longer time to replace all electromagnetic relays by micro processor based static relays. The relay which consists static and electromagnetic relay is also called static relay because the static units obtain the response and the electromagnetic relay is only used for switching operation. ω I1max cos ωt, or VH α I1max I2max sin [ωt –(ωt – α)] α I1max I2max sin α …(4.4). When the relay contacts close simultaneously with an AC single phase power source, because the electrical life of the contacts suffers extreme shortening, care is necessary. Static Instantaneous and Definite Time Overcurrent Relays: The block diagram of an instantaneous overcurrent relay is shown in Fig. Hall Effect Relays 6. Image Guidelines 4. According to the principle of operation and construction, the relay may be classified such as the electromagnetic attraction type, electromagnetic induction type, electrodynamic type, moving coil type, electro-thermal type, physics electric type, and static relays. The choice of directional unit depends upon the type of comparator used. For an overcurrent relay-, For Iinput > Ithreshold ; Ioutput = Present. These relays could not meet practical requirements and hence never reached the commercial stages. But in some semiconductors such as indium arsenide, indium antimonite, indium phosphate, germanium etc., this voltage is enough for measurement with a sensitive moving coil instrument. New developments in commercial relay manufacture are also included. In either of the circuits shown in Fig. Typical EMR Table 1: Physical Size Comparison of SSRs and EMRs Part Package Number of Poles Area per Pole (mm2) Operation occurs when the two ac quantities under comparison are in phase. They are more complicated in static form as compared to their electromagnetic counterparts. Before uploading and sharing your knowledge on this site, please read the following pages: 1. With n = 7 or 8, the characteristic becomes extremely inverse. Static Relay Presentation 1. Time delay overcurrent relays are used in overcurrent protection of utility equipment, distribution circuits, protection of transformers, generators, motors etc. Content Guidelines 2. Rectifier Bridge Relays 4. No effect of Gravity on operation of static relay. Memory 4. The general expression for the operating time of a static time-current relays may be given as –. The resistivity of some metals and semiconductors at low temperature changes when exposed to the magnetic field. These were the first to be developed in the series of static relays. Privacy Policy 9. This is due to the absence of moving parts, which facilitates the application of automatic reclosing of breakers. The first static relays developed were the high speed differential relays and the distance relays. Actually relay is nothing but a : 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-frequency, and under-frequency. If transductor is employed as amplitude comparator its sensitivity is limited due to the sensitivity of the slave relay in its output circuit. However, static overcurrent relays offer several advantages over the electromagnetic form: Before uploading and sharing your knowledge on this site, please read the following pages: 1. Plagiarism Prevention 5. When the relay is turned ON and OFF using a SCR, the SCR serves as a half wave power source as it is, and there are ample cases where the SCR is easily restored. The amplified output is given to the output circuit to cause trip/alarm. Compact in size – The size of a single three-phase overcurrent relay may be about one-fourth of three electromagnetic relays. Multiplexer and Analog to digital converter 5. If time delay is desired, a timing circuit is introduced before the level detector. Prohibited Content 3. No over-reaching tendencies and more accurate time-current characteristic. For a normally open output, the energized coil forces the armature to put the electrical contacts into the ON state. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion. A potential difference VH, called the Hall voltage, is developed between the top and bottom of the slab. For maximum sensitivity of relay ɸ should be equal to θ. Time delay given by the timing circuit shown in Fig. Content Filtration 6. Copyright 10. Typically, an EMR needs 5 to 15 ms to switch and settle—a delay which is not acceptable in som… Less maintenance, long life and not affected by shock and vibration. A transductor operates so as to present variable impedance to currents flowing through the operating windings, the magnitude of this impedance being varied by the current flowing through the control winding. Uploader Agreement. Solid State Relays We will discuss all of them in detail below. Figure 4.6 illustrates the basic Hall generator where the Hall crystal in the form of a slab is connected to a battery so that a current I flows through the slab in the manner shown in the figure and the magnetic field is applied so that it is perpendicular to the slab of the Hall crystal. Voltage so developed is very small and it is difficult to detect it by or! Be eliminated by cross-connecting two Hall generators, as in case of overcurrent! Of some metals and semiconductors at low temperature changes when exposed to the magnetic.. Its types: the block diagram of an issue to a summation (. By means of phase comparator [ Fig small value of the order 0.02. 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