4. Therefore solid state relays are also called as static 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. Actually relay is nothing but a Fault current level detectors are termed overcurrent relays. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Transistor Relays 5. Rectifier Bridge Relays 4. A potential difference VH, called the Hall voltage, is developed between the top and bottom of the slab. Overcurrent ground fault protection can be obtained with only one overcurrent relay by connecting it across a zero phase sequence current filter. An electromechanical relay is robust and versatile. Time delay overcurrent relays are used in overcurrent protection of utility equipment, distribution circuits, protection of transformers, generators, motors etc. The first static relays developed were the high speed differential relays and the distance relays. Content Filtration 6. CPU 3. Position of relay: Relay can be installed at any location and at any position. 1. STATIC RELAY NAME- ROHIT KUMAR MARNDI REGD NO- F15152002039 BRANCH- ELECTRICAL ENGINEERING YEAR:- 2015-18 GOVT. Privacy Policy 9. each type of relay. Terms of Service 7. The book is a thoroughly revised and updated second edition of a successful text. Static relays 3. Report a Violation 11. The same construction may be used for under-voltage, overvoltage or earth fault relays too. Transductor (Magnetic Amplifier Relays) 3. The dynamic assignment is performed by the inverse ARP feature. No effect of Gravity on operation of static relay. Many are downloadable. Cisco routers support all network layer protocols using Frame Relay, such as IPv4, IPv6, IPX and AppleTalk. Both types of relay control electrical circuits through a switch that is open or closed depending upon an electrical input. A telephone type relay can be directly operated from the Hall voltage. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. 3. 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 … However, static overcurrent relays offer several advantages over the electromagnetic form: 4.2. What is a Relay? Smoothening circuit and filters are introduced in the output of the bridge rectifier. The effect of this is to drive both the limbs on which the operating winding is wound into saturation. 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. The control windings are energized with dc and the operating windings with ac. These were the first to be developed in the series of static relays. 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. With n = 7 or 8, the characteristic becomes extremely inverse. Where, I is the relay current, t is the time of operation and n is the characteristic index of relay and K is constant. Static Instantaneous and Definite Time Overcurrent Relays: The block diagram of an instantaneous overcurrent relay is shown in Fig. Relay is a statically typed and type-inferred language, allowing programs to be fully typed while requiring just a few explicit type annotations. Copyright 10. 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. In an actual relay, Ithreshold can be adjusted. Extremely inverse overcurrent relays are used for the fuse coordination and thermal protection of transformers and induction motors. 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. Prohibited Content 3. Uploader Agreement. Plagiarism Prevention 5. The induction cup type of electromagnetic relays, even though are very sensitive, have dead zone in their operation. Transductor (Magnetic Amplifier Relays) 3. ered to a load. 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. Actually, a relay is nothing but a combination of one or more open or closed contacts. History of Relay. 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. Thus directional relay is a double actuating quantity relay with one input as current I from CT and the other input V from PT. It incorporates the latest developments in semiconductor technology and its applications to power system protection. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. The secondaries of the line CTs are connected to a summation circuit (not shown in the figure). When the voltage on the timing capacitor VC attains the threshold value of the level detector II, tripping occurs. 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. 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. 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. Figure 4.15 represents the static directional relay with two inputs (V and I). 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. Solid State Relays We will discuss all of them in detail below. 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. 4.2 (b)]. Electronic Relays 2. The Hall crystal as phase comparator has gained popularity only in Russia. Input Module 2. If transductor is employed as amplitude comparator its sensitivity is limited due to the sensitivity of the slave relay in its output circuit. This is because the induction disc characteristics of the overcurrent relays (inverse characteristics) are not amenable to simple mathematical analysis. In this article, the different types of relays like overload protection relay, solid state relay, solid state contactor relay, Buchholz relay, Mercury Wetted relay and … In instantaneous overcurrent relays, the time delay circuit shown in Fig. However, it takes up more room and is slower than an SSR. Static relays are classified according to the type of the measuring unit or comparator as follows: 1. Get ideas for your own presentations. [gravityform id="1" title="false" description="false" ajax="true"]. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. When this happens a voltage is induced in the output winding and the relay gets energised. Electromagnetic relays 2. Static relay with output contacts – A static relay having a contact in one or more of its output circuit (s). Typically, an EMR needs 5 to 15 ms to switch and settle—a delay which is not acceptable in som… Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. When the input to measuring unit is less than the threshold value, the output of the level detector is zero. 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 component of the static relay is shown in the figure below. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. Magneto resistors are sensitive to the magnetic field strength and not to the rate of variation. Inverse-time relays are used where the source impedance is much smaller than the line impedance. Image Guidelines 4. For an overcurrent relay-, For Iinput > Ithreshold ; Ioutput = Present. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. 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. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion. The basic R-C circuit can also be arranged in several series-parallel combinations to have different values of TC. Terms of Service 7. 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; … Digital input/Communication module Input Module The Power system operates with analog parameters. Such a characteristic is known as definite time characteristic of overcurrent relay. This phenomenon is called the Hall Effect. By varying values of R and C the time can be varied without difficulties. That is why a heavy duty telephone type relay is employed with large setting. These latter types of applications are described in detail in “Phase Control Using Thyristors” (AN1003). = KH ɸmax Imax [cos α – cos (2ωt – α)] … (4.1). 4.11 (a). 4.11 (a) is deleted. Disclaimer 8. Rectifier Bridge Relays 4. Such a circuit would need only one level detector. This relay consists of two rectifier bridges and a moving coil or polarized moving iron relay. 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. Static Relays: Analog input signals are processed by solid state devices; ... less necessary control energy compared to the output power results in higher power gain than with an electromagnetic relay. Output module 6. Two basic arrangements of relays based on transistor comparators are shown in Fig. Where, VT is the threshold value of the level detector II. The characteristic becomes a straight line parallel to current axis for n = 0. Because of the high cost of Hall element, low output and large temperature error, this comparator is normally not used. The block diagram of a static overcurrent time relay is shown in Fig. In the case of transmission lines supplied from both ends, it is employed with directional relays. In case of static overcurrent relays instantaneous reset is possible. Relay will operate when IS < I cos(ɸ – θ). 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 Electronic Relays 2. Functions: 1 relay can perform various functions. Account Disable 12. Content Filtration 6. The inputs are supplied to the phase comparator. For complete protection against phase and ground faults, generally three CTs and two phase and one ground overcurrent relays are employed in the system. 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. In the latter arrangement one ac quantity is connected to the control grid and the other to the screen grid of the electronic tube. The performance of CT under short-circuit condition is also improved. The electrical protective relay can be broad, classified into two categories (i) Electromagnetic Relay and (ii) Static Relay. Memory 4. Static relays are classified according to the type of the measuring unit or comparator as follows: 1. 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. The double frequency term can be eliminated by cross-connecting two Hall generators, as illustrated in Fig. The most common are relay comparators based on rectifier bridges, which can be arranged as either amplitude or phase comparators. The voltage so developed is very small and it is difficult to detect it. In static relays it is advantageous to choose a circuit accommodating a wide range of alternative inverse time characteristics, precise minimum operating levels, definite minimum times and additional high set features, if necessary. 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 device thus acts as a pure phase comparator. POLYTECHNIC MAYURBHANJ, TIKARPADA 2. With n = 1; It = K. The characteristic becomes inverse characteristic. When the coil is de-energized, springs can move the contacts back to the OFF position. After operation of the measuring unit, the output is amplified by the amplifier. Report a Violation 11. Static Relay Presentation 1. The relay is simple, reliable and has small operating time, easy adjustment and good sensitivity. 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. 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). Their architecture can look confusing but we can just simplify whole architecture into these major categories 1. 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. INTRODUCTION In a protection relay, the term 'static' refers to the absence of moving parts to create the relay characteristic. The choice of directional unit depends upon the type of comparator used. 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 ”. 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. 2. 4.11 is given as –. The transductor relays are mechanically very simple and are quite reliable. Copyright 10. 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. Protective Relays 3. 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. Content Guidelines 2. The components used were electronic valves for measuring unit. Gravitational force can affect the relay. Share yours for free! This is due to the absence of moving parts, which facilitates the application of automatic reclosing of breakers. Relays are broadly classified into three categories depending upon their construction and working. Each group may comprise only one winding but if there is more than one winding in a group all those windings are magnetically linked. Prohibited Content 3. Where, IS is the magnitude of set current, ɸ is the phase angle between V and I and θ is characteristic angle. Overcurrent relays are also employed in conjunction with distance relays to provide backup protection. A new chapter on Microprocessor Applications to Protection has been added. 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). The term ‘static ’ implies that the relay has no moving parts. New developments in commercial relay manufacture are also included. [gravityform id="1" title="false" description="false" ajax="true"]. 1. Image Guidelines 4. However, static overcurrent relays offer several advantages over the electromagnetic form: 1. Instantaneous overcurrent relays are used for short-circuit protection of large equipment. Compact in size – The size of a single three-phase overcurrent relay may be about one-fourth of three electromagnetic relays. Fault current level detectors are termed overcurrent relays. A transductor comprises essentially a magnetic core carrying two groups of windings usually known as operating windings and control windings. The resistivity of some metals and semiconductors at low temperature changes when exposed to the magnetic field. Electromagnetic relays are those relays which are operated by electromagnetic action. Multiplexer and Analog to digital converter 5. 5. The amplified output is given to the output circuit to cause trip/alarm. Relays: Classification and Design | Devices | Electrical 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. This relay has to be installed straight only and away from magnetic field. On the other hand the windings of the different groups are not magnetically linked. Types of Relays. The comparator used in directional overcurrent relay may be Hall Effect generator; Rectifier bridge comparator; Instantaneous coincidence comparator or integrating coincidence phase comparator. The output of the level detector is amplified and in case a timer is necessary, the output is applied to the output device through the timer. 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. For a normally open output, the energized coil forces the armature to put the electrical contacts into the ON state. Before uploading and sharing your knowledge on this site, please read the following pages: 1. Then it suddenly increases and becomes very large for a small value of operating current. Plagiarism Prevention 5. 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. The numeric relay can be called as a miniature computer as they both have similar hardware architecture with slight differences. Gauss Effect Relays. A single coil which permits use … Learn new and interesting things. 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. Fitzgerald presented a carrier current pilot relaying scheme for the protection of transmission lines in 1928. The directional overcurrent relay can be made either instantaneous or time-lag type. Static relay without output contacts – A static relay having no contact in its output circuit (s). For obvious reasons of obtaining selectivity overcurrent relays are made directional. Privacy Policy 9. 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. Electrical Engineering, Devices, Relays, Static Relays, Static Overcurrent Relays and Its Types. 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. 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 term ‘static’ implies that the relay has no moving mechanical parts in it. 4.2 (a)] and the other makes use of a phase comparator [Fig. Digital / Numerical relays They can also be classified as: 1. 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. 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Also employed in conjunction with distance relays to provide backup protection operation mechanism selectivity relays. And sharing your knowledge on this site, please read the following pages: 1 transistorized circuits require about dc! [ Fig 7 or 8, the characteristic becomes a straight line parallel to current axis for n = ;! Time to replace all electromagnetic relays, the output winding and the other input V PT. Eliminated by cross-connecting two Hall generators, as in case of static overcurrent relays offer several advantages over electromagnetic! Equipment, distribution circuits types of static relay protection of large equipment even though are very,... Changes when exposed to the magnetic field and current attained the threshold value ( value... View static relays are used in overcurrent protection of utility equipment, distribution circuits, protection of large.! Or mumetal and has small operating time of a single three-phase overcurrent relay by connecting across... 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Large temperature error, this effect is noticeable at room temperature, as in case of bismuth magnitude.