After operation of the measuring unit, the output is amplified by the amplifier. The secondaries of the line CTs are connected to a summation circuit (not shown in the figure). For maximum sensitivity of relay ɸ should be equal to θ. What is a Relay? Copyright 10. Digital input/Communication module Input Module The Power system operates with analog parameters. 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). Overcurrent ground fault protection can be obtained with only one overcurrent relay by connecting it across a zero phase sequence current filter. They are more complicated in static form as compared to their electromagnetic counterparts. An electromechanical relay is robust and versatile. Plagiarism Prevention 5. Gravitational force can affect the relay. A telephone type relay can be directly operated from the Hall voltage. Relay will operate when IS < I cos(ɸ – θ). Hence less panel space is required in case of static overcurrent relays. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. The high powered analog signals are stepped down with current tran… STATIC RELAY NAME- ROHIT KUMAR MARNDI REGD NO- F15152002039 BRANCH- ELECTRICAL ENGINEERING YEAR:- 2015-18 GOVT. : 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. Figure 4.15 represents the static directional relay with two inputs (V and I). The amplified output is given to the output circuit to cause trip/alarm. Where, IS is the magnitude of set current, ɸ is the phase angle between V and I and θ is characteristic angle. = KH ɸmax Imax [cos α – cos (2ωt – α)] … (4.1). This phenomenon is called the magneto resistivity or Gauss effect. A new chapter on Microprocessor Applications to Protection has been added. The relay is simple, reliable and has small operating time, easy adjustment and good sensitivity. This is due to the absence of moving parts, which facilitates the application of automatic reclosing of breakers. Terms of Service 7. 1. Such a circuit would need only one level detector. Gauss Effect Relays. 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 ”. When this happens a voltage is induced in the output winding and the relay gets energised. Electromagnetic relays 2. Such relays became popular because of development of semiconductor diodes. 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. The operation depends on the difference of the average rectified voltage (V1-V2).Here the rectifiers are not protected against higher currents. Typically, an EMR needs 5 to 15 ms to switch and settle—a delay which is not acceptable in som… No over-reaching tendencies and more accurate time-current characteristic. Uploader Agreement. 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. 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. Such a relay is considered better than Hall Effect relay because of simpler construction and circuitry. Prohibited Content 3. This relay consists of two rectifier bridges and a moving coil or polarized moving iron relay. 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. The inputs are supplied to the phase comparator. Therefore solid state relays are also called as static relays. 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 However, it takes up more room and is slower than an SSR. The resistivity of some metals and semiconductors at low temperature changes when exposed to the magnetic field. 3. As there is no moving part, operating time of the order of 0.02 s (1 cycle) can be achieved. The block diagram of a static overcurrent time relay is shown in Fig. For obvious reasons of obtaining selectivity overcurrent relays are made directional. Inverse-time relays are used where the source impedance is much smaller than the line impedance. Memory 4. Directional relay senses direction of power flow by means of phase angle between V and I. The static relay is the next generation relay after electromechanical type.The Solid Static relays was first introduced in 1960’s. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. For a normally open output, the energized coil forces the armature to put the electrical contacts into the ON state. Relays are broadly classified into three categories depending upon their construction and working. Report a Violation 11. 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. Before uploading and sharing your knowledge on this site, please read the following pages: 1. The comparator used in directional overcurrent relay may be Hall Effect generator; Rectifier bridge comparator; Instantaneous coincidence comparator or integrating coincidence phase comparator. Because reverse ARP is enabled by default, no additional commands are required. The book is a thoroughly revised and updated second edition of a successful text. Get ideas for your own presentations. If you have a dynamic IP address or multiple static IPs, this isn't as much of an issue. The same operation is repeated on the other limb during next half cycle. 4.11 (a) is deleted. A single coil which permits use … The dynamic assignment is performed by the inverse ARP feature. When the phase angle between V and I exceeds certain predetermined value, the directional relay operates with a condition that the current is above the pick-up value. A potential difference VH, called the Hall voltage, is developed between the top and bottom of the slab. 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. 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. Image Guidelines 4. Gauss Effect Relays. 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. Transistor relays are the most widely used static relays. However, static overcurrent relays offer several advantages over the electromagnetic form: 1. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion. Instantaneous overcurrent relays are used for short-circuit protection of large equipment. In some metals, this effect is noticeable at room temperature, as in case of bismuth. Address assignment to DLCI is achieved by dynamic or static address assignment. Terms of Service 7. Static relay with output contacts – A static relay having a contact in one or more of its output circuit (s). Types of solid state relays include reed relay coupled SSR, … Content Guidelines 2. Before uploading and sharing your knowledge on this site, please read the following pages: 1. Types of Relays. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. New developments in commercial relay manufacture are also included. 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. 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; … For complete protection against phase and ground faults, generally three CTs and two phase and one ground overcurrent relays are employed in the system. INTRODUCTION In a protection relay, the term 'static' refers to the absence of moving parts to create the relay characteristic. Overcurrent relays are also employed in conjunction with distance relays to provide backup protection. 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. Transductor (Magnetic Amplifier Relays) 3. Time delay relays 2. 4.11 is given as –. Functions: 1 relay can perform various functions. Actually relay is nothing but a Transistor Relays 5. 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. 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. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. In an actual relay, Ithreshold can be adjusted. The technique of overcurrent relaying is still widely used as a means of fault detection on distribution system and on transmission lines supplied from one end. 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. These latter types of applications are described in detail in “Phase Control Using Thyristors” (AN1003). One uses an amplitude comparator [Fig. Input Module 2. 4.11 (a). 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. 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 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. If transductor is employed as amplitude comparator its sensitivity is limited due to the sensitivity of the slave relay in its output circuit. Both types of relay control electrical circuits through a switch that is open or closed depending upon an electrical input. If time delay is desired, a timing circuit is introduced before the level detector. The Hall crystal as phase comparator has gained popularity only in Russia. 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. Cisco routers support all network layer protocols using Frame Relay, such as IPv4, IPv6, IPX and AppleTalk. 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. Less maintenance, long life and not affected by shock and vibration. View Static Relays PPTs online, safely and virus-free! Output module 6. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. 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). Share yours for free! Indium antimonite and indium arsenide are more sensitive in comparison to bismuth or mumetal. Learn new and interesting things. Electronic Relays: These were the first to be developed in the series of static relays. The directional overcurrent relay can be made either instantaneous or time-lag type. 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. With higher value of n, the characteristic becomes more and more inverse. Typical EMR Table 1: Physical Size Comparison of SSRs and EMRs Part Package Number of Poles Area per Pole (mm2) 4.5. Content Guidelines 2. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. 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 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. The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. Content Filtration 6. Multiplexer and Analog to digital converter 5. Hall Effect Relays 6. POLYTECHNIC MAYURBHANJ, TIKARPADA 2. History of Relay. 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. 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. ered to a load. In static directional relays this problem is less serious because static comparators are very sensitive and it is comparatively easier to make a static directional unit reliable down to 1% of system voltage which is well within the minimum fault voltage. The induction cup type of electromagnetic relays, even though are very sensitive, have dead zone in their operation. A transductor comprises essentially a magnetic core carrying two groups of windings usually known as operating windings and control windings. Two basic arrangements are shown in Fig. The voltage so developed is very small and it is difficult to detect it. In either of the circuits shown in Fig. This effect depends upon the ratio of depth to width and increases with the increase in this ratio. 4. The basic R-C circuit can also be arranged in several series-parallel combinations to have different values of TC. With n = 1; It = K. The characteristic becomes inverse characteristic. When the input to measuring unit is less than the threshold value, the output of the level detector is zero. The output of phase comparator is fed to the level detector. No effect of Gravity on operation of static relay. Rectifier Bridge Relays 4. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. Static Relay Presentation 1. Nonlinear resistors are used to have other time characteristics. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. The effect of this is to drive both the limbs on which the operating winding is wound into saturation. Smoothening circuit and filters are introduced in the output of the bridge rectifier. each type of relay. These were the first to be developed in the series of static relays. In electrical systems, a static relay is a type of relay, an electrically operated switch, that has no moving parts. 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. The measuring unit determines whether the quantity has attained the threshold value (set value) or not. The first static relays developed were the high speed differential relays and the distance relays. In instantaneous overcurrent relays, the time delay circuit shown in Fig. For an overcurrent relay-, For Iinput > Ithreshold ; Ioutput = Present. The performance of CT under short-circuit condition is also improved. Operation occurs when the two ac quantities under comparison are in phase. The general equation for time characteristic is given as –. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. 2. 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. 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. If the relay picks up at top value current i.e., Ip = 1. then t = K M/In – 1, The static overcurrent time relays can have the following typical characteristics. 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Circuits through a switch that is open or closed depending upon an electrical input eliminated cross-connecting... By means of phase angle between V and I and θ is characteristic angle after! Element, low output and large temperature error, this effect depends upon the ratio of depth to and...