Inductive and capacitive reactance have opposite effects in relation to frequency. Im trying to measure the coil inductance of a relay when the relay is on and the normally open pairs of contacts are closed. Aug 04, 2015 if you make the operating characteristics of reactance relay on rx diagram then it will be straight line. State the difference between calculating impedance in a series ac circuit and in a parallel ac circuit. The microcomputer sends a tripping signal instantaneously if the measured value of x is less than xi. The digital protective relay is a protective relay that uses a microprocessor to analyze power system voltages, currents or other process quantities for the purpose of detection of faults in an electric power system or industrial process system. Systems engineering of electrical power has also been. In reactance relay the operating torque is obtained from the current and the restraining torque by the current and voltage of the directional. The micro51 operates from conventional 5a or 1a secondary current transformers. Microprocessor distance relays use equations to restrain or operate.
The microprocessor may use some kind of counting technique, or use the discrete fourier transform dft to implement the algorithm. All values of fault impedance which will cause the relay to close its contacts lie in the shaded areas. Tell a friend about us, add a link to this page, or visit the webmasters page for free fun content. Ieee 2011 electrical power and energy conference outline introduc. Distance element reach a, nondirectional mho characteristic b. Microprocessorbased distance relays 19 reactance for the first zone of protection. The samples are used to determine the magnitude of the signal. Selfinductance, or simply inductance, is the property of a circuit whereby a change in current causes a change in voltage in the same circuit. A relay that functions when the circuit admittance, impedance, or reactance increases or decreases beyond a predetermined value. Reactance modulator circuit operation and troubleshooting.
For the love of physics walter lewin may 16, 2011 duration. Switchgear and protective devices 310 modulei 10 hours protective devices. This paper evaluates the performance of a transmission line protection scheme using microprocessor based protective and electromechanical relays using discrete components. Micro51 microprocessorbased overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. Series capacitors cancel out the inductive reactance of a line. Numerical protective relays are sampled data systems, so the sampling block in the figure denotes the capture of instantaneous samples of the phase quantities. The unit has lcd for displaying the fault current at the time of. In reactance relay the operating torque is obtained from the current and the restraining torque by the current and voltage of the directional element. Rebirth of negativesequence quantities in protective. If the voltage of the 60 hz ac power source is 480 volts rms, and the motor initially draws 75 amps rms when the doublepole singlethrow switch closes, how much inductance l must the motor windings have. Ultype rhh wires with class b stranding, in cradled configuration. Impedance calculation algorithm for microprocessor based digital protective relay international conference on innovative and advanced technologies in engineering march2018 74.
Reactance relay article about reactance relay by the free. Similarly, the output of a logic function is activated, that is, high or deactivated, that is, low. Larger reactance leads to smaller currents for the same voltage applied. Inductive reactance rises with an increase in frequency, and capacitive reactance falls. This implies that reactance relay is an overcurrent relay with directional restraint. Relay classification, principle of different types of electromagnetic relay. In this research paper, study the impact of apparent reactance injected by three tcsr on algerian transmission line protected by distance relay protection in presence single phase phase a to earth fault with. The resistance of a circuit like this can be made so small that it has a negligible effect compared with the capacitor, and so we can assume negligible resistance.
Philosophy of protection, nature, causes and consequences of faults, zone of protection, requirements of a protective scheme, basic terminology components of protection scheme. The main advantage of using this relay is its capability of replacing all specific purpose relays by a single microprocessor based relay can be used for protection against various faults like over current, over voltage, thermal overload etc by just modifying the program. Siprotec microprocessor based protective relay history of protective relay. Form of impedance relay, the operation of which is a function of the reactance of a circuit. Relay logic functions the microprocessor implements all the e. The current element developed positive torque and a currentvoltage developed directional element which opposes the current element depending on the phase angle between current and voltage. There is one type of relay which functions depending upon the distance of fault in the line. For calculations you can choose which formula to use for inductive.
The relay is selfpoered from the current, therefore, there is no continuous drain on. In this paper, we describe one and twoended impedance based fault location experiences. Ac capacitance and capacitive reactance in ac circuit. By using the boolean simplification, we can represent the logic in a microprocessor based relay in a few different ways. Latching relays with magnetic holding and with electrical or manual resetting can be provided.
Determining the coil inductance of a relay when the relay is. Application guidelines for microprocessorbased, high. The present component created positive torque and a present voltage created directional component which contradicts the present component relying upon the stage point amongst current and voltage. A communications based protection scheme where high speed overreaching. The current research is focused on impedance relays. In electric and electronic systems, reactance is the opposition of a circuit element to the flow of current due to that elements inductance or capacitance. For each case calculate the resulting current fl ow and sketch the relevant phasor diagram. An mpedance relay measures the line impedance between the fault point and relay location. Protective relays, associated communication systems, voltage and current sensing devices. More specifically, the relay operates depending upon the impedance between the point of fault and the point where relay is installed.
This relay consists of two units an overcurrent element and a currentvoltage directional element. Abstractphase and ground directional elements are relied on for fast and secure protection throughout the power system. Reactance is symbolized by the capital letter x and is measured in ohms just like resistance r. Capacitors and capacitive reactance consider the capacitor connected directly to an ac voltage source as shown in link. Unit i introduction of relays a relay comprises of an electromagnet and a contact unit. Reactance relay is normally preferred for protection against a earth fault only from eee 5 at gudlavalleru engineering college. Reactance modulator circuit operation and troubleshooting october 10, 2017 february 8, 2019 engineeering projects the reactance is efficient and provides a large deviation. Ac capacitor circuits reactance and impedance capacitive. The relay has a rated ac voltage of 110v and a rated current of 21ma. Ac capacitance and capacitive reactance the opposition to current flow through an ac capacitor is called capacitive reactance and which itself is inversely proportional to the supply frequency capacitors store energy on their conductive plates in the form of an electrical charge.
The relay whose working depends on the distance between the impedance of the faulty section and the position on which relay installed is known as the impedance relay or distance relay. Resistance can also be energy transferred such as electrical energy which is converted to mechanical energy. Impact of apparent reactance injected by tcsr on distance relay in presence phase to earth fault article pdf available in advances in electrical and electronic engineering 1. Ac inductance and inductive reactance the opposition to current flow through an ac inductor is called inductive reactance and which depends lineally on the supply frequency inductors and chokes are basically coils or loops of wire that are either wound around a hollow tube former air cored or wound around some ferromagnetic material iron. Microprocessor based relays perform very well and their cost is relatively low. A reactance relay measures the reactance of the line at the relay location. The abb relay protection and substation automation history goes back to the.
Use of the rx diagram in relay work ge digital energy. Description the powerlogic digital relay figure 1 is a multifunction, microprocessor based device which performs these functions. Value decreases for higher f current leads voltage by 90. Pdf on dec 27, 2009, parag kanjiya and others published microcontroller based numerical. The article is a continuation of a set of the authors previous publications about the reliability of the microprocessor based protective devices. Pdf mho distance relay of transmission line high voltage.
Value does not change with f current and voltage are in phase. Impact of apparent reactance injected by tcsr on distance. It can be seed that as the inductance of an inductor increases, the inductive reactance is also increases. In case of a fault, the relay measures the reactance of the line up to the fault point from the relay location. The statistical data introduced by the author coincide with data of other authors and con. If x is greater than xl but less than x2 it sends the tripping signal after a predetermined delay. Consider the above figure which plots the inductive reactance versus inductance at a fixed frequency. Tutorial on operating characteristics of microprocessor.
Microcontroller based numerical mho distance relay for. Fundamentals and improvements for directional relays. The right hand side pole is energized by the voltage and the flux produced by it interacts with the polarizing flux for producing the restraining torque, k 2 v 2. Sep 02, 2015 at the zero frequency, the inductive reactance is zero and as the frequency is increasing, inductive reactance advances appropriately. Electronics club impedance and reactance input impedance. Activating the contact unit using electromagnetic attraction, which is produced when electric current exceeding the. The induction cup or double induction loop structures are best suited for actuating reactance type distance relays. The book is a thoroughly revised and updated second edition of a successful text. Microcontroller based distance protection of transmission line using reactance relay. It incorporates the latest developments in semiconductor technology and its applications to power system protection. Reactance relay is normally preferred for protection against.
Answer 4 the light bulb will glow brighter when the iron core is moved away from the wire coil, due to the change in inductive reactance x l. The setting of r1 should be at least if relay r2 were given a higher setting than r1 maloperation would occur in the protection. When one circuit induces current flow in a second nearby circuit, it is. Reactance relay mho relay is a distance relay with inherent directional element. Pdf impact of apparent reactance injected by tcsr on. These relays are known as distance relay or impedance relay.
Capacitive reactance capacitive reactance symbol is xc unit is. Given the power factor and values of x and r in an ac circuit, compute the value of reactance in the circuit, and state the type of reactance that must be connected in the circuit to correct the power factor to unity 1. Why is the characteristic of a reactance type distance relay. Sep 01, 2018 there is one type of relay which functions depending upon the distance of fault in the line. Directional reactance and the mhoscheme for distance protection are discussed here. This is true for the threephase fault shown also for a phasetophase fault and for a phase distance function only. Capacitive reactance can be calculated using this formula. Electronic and microprocessor based relays have current setting steps of 5% 2, 3. Mdf microprocessor frequency relay electromechanical.
Microcontroller based distance protection of transmission line. Inductive reactance worksheet ac electric circuits. Reactance relay is an overcurrent relay with directional limitation. A digital filter based on fourier techniques calculates the fundamental component from the samples captured in the memory of the device. Some fault detectors used in microprocessorbased relays utilize the zero and. Twoct equivalent circuit with an external fault note that the side a and side b impedances must be equal for the overcurrent relay to measure zero current for an external fault. Microprocessor relays with logic and communication capabilities can accomplish this type of scheme by using either hardwired trip contacts or by using communication signals between each other to transfer statuses. With advances in technology, protective relays have progressed from electromechanical, to solid state to microprocessor based relays.
The protection schemes proposed are based on impedance relay. Capacitive reactance is the opposition that a capacitor offers to alternating current due to its phaseshifted storage and release of energy in its electric field. Observe that for the balance point fault, the v is exactly equal to iz. Microprocessor based protections are more reliable, flexible and faster than conventional protection schemes. The directional element is so designed to give maximum torque angle mtarca of 90 degree. Relay logic is very important to understand the microprocessorbased relay. Ignore any wire resistance, and assume the motors only opposition to current in a lockedrotor condition is inductive reactance x l. Istance relays perationdepend on the agnitude of the current or ltage of the circuit.
Electrical period 2 theory induction and inductive. Mho distance relay loadability calculation examples. Data communication, micro controller, digital logiccomputer design, relay, microprocessor based impedance relay, high voltage power lines. The mdf is a digital frequency relay intended to sense hazardous under frequency or over frequency conditions and initiate selective load shedding to preserve service continuity to other loads. In addition to customizing specific microprocessor based relay capabilities, skilled integration engineers can also help utilities and industrial facilities design their microprocessor based relay protection systems in such a way as to fully leverage the inherent benefits of the relays and maximize each relay s value. Chapter 2 introduction to microprocessor based control. Real time calculations of resistance and reactance for transmission line protection by digital computer 1970 elec. Protection and control device numbers and functions bulletin numbers 1500, 7000, 7760, 7762. Relay scheme design using microprocessor relays a supplement to relay trip circuit design by ieee psrc 1999 4 1 introduction microprocessor based relays have been replacing electromechanical and solid state technology relays for several years. A collection of technical papers representing modern solutions, 2014. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
This induction type reactance relay performance is not affected by arc resistance during the occurrence of the fault. Wire conductivities are 100 percent iacs copper and 61 percent aics aluminum, and aluminum conduit is 45 percent. Microprocessor based relay hardware architecture sub harmonic detection process principle of sub harmonic detection operationsminute detector results and discussions. These relays are implemented on a dsp tms320f2812 and their performance is evaluated which is based on operation time, dsps execution time and grading margin. It is like resistance, but it also takes into account the effects of capacitance and inductance. By varying commands to the analogue multiplexer the required input signals for different relaying characteristics such as impedance, reactance. In some solid state relays, a simple microprocessor does some of the relay logic, but the logic is fixed and simple. Worked examples, chapter 1 151 worked example 1 q a 2 k esistr or, a pere0. Mdf microprocessor frequency relay the mdf is a digital frequency relay intended to sense hazardous under frequency or over frequency conditions.
Reactance, inductive and capacitive college physics. Mho relay admittance or angle admittance relay my tech info. This relay comprises of two components an overcurrent component and a present voltage directional component. Aug 15, 2017 in a given component wire, resistor, inductor, transistor, etc resistance is energy lost typically as heat. Electric power topic tutorial for more comprehensive lecture email on tdconsultants. Reactance is similar to electric resistance, but it differs in several respects. Jun 20, 2017 this feature is not available right now.
Impedance symbol z is a measure of the overall opposition of a circuit to current, in other words. The relay can be on or off, that is, it has two stable states. If the calculations are further based on the premise that for a bus fault the voltage presented to the type ifcv relay is 0, then the type ifcv can be coordinated with the bus andor system relaying on a straight overcurrent basis. We define terms associated with fault location, and describe several impedance based methods of fault location simple reactance, takagi, zerosequence current with angle correction, and twoended negativesequence. Consider that the 51 relay is a lowimpedance, microprocessorbased overcurrent relay. Distance relay or impedance relay working principle types. A digital protective relay may also be called a numeric protective relay. Impedance calculation algorithm for microprocessor based. Protection and control device numbers and functions. Distance relay fundamentals 63 fault, operation does not occur because izv and v are 180 out of phase. Engineering data ac resistance and reactance 184 data subject to change without notice. Both are similar to resistance and are measured in ohms, but resistance remains the same, whatever the frequency.
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