Abstract modern distance relays are designed with different characteristics in order to demonstrate that they can provide better protection and at the same time. Electrical characteristics of relays learning about electronics. After normalization of line, the setting is again changed to 100 %. Distance relay element design schweitzer engineering. The apparent impedance so calculated is compared with the reach point impedance. They have earned a welldeserved reputation for accuracy, dependability, and reliability. Before going in to the details of what is a sensor, what are the different types of sensors and applications of these different types of sensors, we will first take a look at a simple example of an automated system, which is possible because of sensors and many other components as well. Some numerical relays measure the absolute fault impedance and then determine whether operation is required according to impedance boundaries defined on the rx diagram.
Directional elements respond to the phase shift between a polarizing quantity and an operate quantity. Protection relay characteristics for different settings relay a. It is the tripping relay in pilot schemes and as the backup relay in step distance schemes. The fault impedance is calculated by the distance protection. Also, relays are the best way for galvanic insulation between high and low voltage portions of a circuit. Rated coil voltage the voltage that the relay is supposed to receive when you energize it. Relay which means the solid static relays can perform tasks that the electromechanical relay can perform. Pickup is defined as that value of current or voltage which will just close the relay contacts from the 0. Mar 20, 2019 distance protection is a nonunit system of protection, which measures the impedance between the relay location and the point where the fault is incident and compares it with the set value. The admittance relay is the most commonly used distance relay. Due to the effect of current infeed from other sources into the faulted zone, the zone. Some of the most commonly utilised impedance shapes include the mho, offset mho, quadrilateral, peanut and lens.
Overreaching distance relays tripping under load have played a part in many major blackouts. Over current relay and its characteristics electrical concepts. Distance relay or impedance relay working principle types. In short, a phase comparator compares two input quantities in phase angle vertically irrespective of the magnitude and operates if the phase angle between them is of a distance function that uses positive sequence voltage as the polarizing signal. Working of relayshow relay works,basics,design,construction. Fundamentals and improvements for directional relays. Jan 08, 2019 protection schemes can be divided into two major groups. This results in the dynamic and steadystate characteristics shown in figure 4 remember that this. The quadrilateral distance relay is quite better option for the protection of transmission line as it covers minimum area in rx diagram and it is closer to ideal distance relay characteristic10when a shortcircuit fault occurs on a transmission line, distance relays gives protection and trips the circuit breaker by disconnecting the faulty. This impedance between the relay and the fault depends on the electrical distance between them. Aug 04, 2015 if you make the operating characteristics of reactance relay on rx diagram then it will be straight line. The unit protection schemes are based on kirchhoffs current law the sum of the currents entering an. Phase angle comparators test the angle between various voltage and current combinations to produce directional, reactance, mho, and other characteristics.
Advanced distance relay characteristics suitable for. Pickup is defined as that value of current or voltage which will just close the. All mho distance functions require voltage in order to operate. Actually, there is much overlapping of these areas. Distance relays characteristics may be mho, quadrilateral, offset mho. Common timedistance characteristics for three zone distance relay protection. Pdf line protection in hvehvuhv lines is primarily by distance protection due to its selective, reliable and secure operation. Pdf fundamentals of distance protection researchgate. Distance relays characteristics are commonly plotted on the rx diagram are shown in fig. How multiinput comparators can be viewed as a family of twoinput comparators. Ground distance relays understanding the various methods of residual compensation, setting the resistive reach of polygon characteristics, and ways of modeling and testing the relay 2 residual compensation and zerosequence current compensation most ground distance relays are designed so that they measure and can be set in terms of positive. This is the first generation oldest relaying system and they have been in use for many years. There is one type of relay which functions depending upon the distance of fault in the line.
Oct 25, 2017 manta test systems, mts2150 users manual, 2002. Overcurrent protection fundamentals r ced engineering. Typical quadrilateral operation characteristic for distance protection. Traditional distance relays and numerical relays that emulate the impedance elements of traditional relays do not measure absolute impedance. Therefore the fault locator is an integral part of the distance protection function. Other than the electromagnetic relay there are many other types of relays which work on different principles.
The most widely used overload relay is the thermal overload relay where a bimetallic strip is used to turn off the motor. When two different materials are joined together it forms into a bimetallic strip. The distance elements can be simple or complex, with different operating characteristics, with or without directional supervision. Numerical distance protection relay commissioning and.
Which characteristics result from various combinations of comparator inputs. Sep 01, 2018 there is one type of relay which functions depending upon the distance of fault in the line. Latching relays are the same as the singleside stable relays described previously except that the core, yoke, and armature are made from semihard magnetic material and there are at least two coils in the relay. In reactance relay the operating torque is obtained from the current and the restraining torque by the current and voltage of the directional. A number of application aspects have been discussed including shaping of the impedance characteristic, the impact of fault resistance, different. Distance relay with mho characteristics is an inherently directional relay. We already discussed that for fault identification we have to set different parameters in relay. Nov 08, 2017 all these and many other automation tasks are possible because of sensors. Types of relay based on the principle of operation.
The time of operation of such protection is a function of the ratio of voltage and current, i. This is done by comparing a relay s apparent impedance to its prede. Since this type of relay operates based on the impedance of the circuit which in turn depends upon the distance of the fault from the relay location, it is called distance relay. Calculation of distance protection settings in mutually. Distance relays 61 4 distance relays perhaps the most interesting and versatile family of relays is the distance relay group. The basic principle of distance protection involves the division of the voltage at the relaying point by the measured current. Set operate voltage the minimum voltage that the relay needs to close its switch.
Figure 2, and servicing timefault location curves for different values of electrical. The first electrical test made on the relay should be a pickup test. For example, consider the case of a distance function that uses positive sequence voltage as the polarizing signal. Behavior of different distance relay characteristic on lines fed from type1 and type2 wtgu connected radially to grid. In other words, distance relay setting is reduced to 85. These relays are known as distance relay or impedance relay. An overload relay switch works in characteristics with current over time and is different from circuit breakers and fuses, where a sudden trip is made to turn off the motor. Distance relay designers quickly recognized that they can shape various operating characteristics by using different pairs of operating and polarizing signals and a. This will be a little less than the ideal coil voltage. A case study conference paper pdf available november 2015 with 217 reads.
Once the distance protection has provided a trip signal, the value of the fault impedance is displayed in ohms or in. Which characteristics result from various combinations of. Every type of characteristics has different intended function and theories behind. Pdf behavior of different distance relay characteristic on. Why is the characteristic of a reactance type distance relay. A distance relay operates whenever the distance seen by the relay is less than the prespecified impedance. Relays are essential for automation systems and for controlling loads.
If the measured impedance is less than the set value, the relay operates and isolates the faulty section. The impedance relay has a circular characteristic centered at the origin of the rx diagram. In this simulation, mho type distance relay was used as the distance protection scheme. Jan 04, 2012 such a relay is described as a distance relay and is designed to operate only for faults occurring between the relay location and the selected reach point, thus giving discrimination for faults that may occur in different line sections. Protection schemes can be divided into two major groups. But if the system stability or the subsequent action of other relays on a. The solid static relays use analogue electronic devices instead of magnetic coils and mechanical components to create the relay characteristics. Read more over current relay and its characteristics. Distance relays fundamentals ge grid solutions online store. Entitlement to other rights relating to reproductions, copies, adaptations, translations, microfilming. In operating characteristics of an impedance of the circuit is compared with voltage at relay location.
Over current relay and its characteristics electrical. 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. The phase angle comparator may be used to develop relay characteristics other than the mho characteristic by changing the input signals. For a fault right at the relay location, the voltage will be very small approaching zero for a bolted fault, and a selfpolarized. It is nondirectional and is used primarily as a fault detector. Pdf behavior of different distance relay characteristic. Numerical distance protection relay commissioning and testing. In general, a voltage different than the fault voltage is used to polarize the function and this will have an effect on the characteristic. Application of overreaching distance relays ieee psrc. Operating state set when current flows through coil a, the electromagnet made of. Alexander general electric co malvern, pa introduction distance functions have been in use for many years and have progressed from the original electromechanical types thr ough analog types and now up to digital types of functions.
The characteristics for a phase distance function and a ground distance function that use positive sequence voltage polarization are shown in figure 3 1 and are drawn for a phasetophase and phasetoground fault respectively. Unit type schemes protect a specific area of the system i. Setting the quadrilateral characteristic of a distance relay. The value can be displayed and used to determine the fault location. Selection of these characteristics often depends on the required. Impact analysis of statcom on distance relay open access. The numerical distance protection relay used is rel 5112. Distance protection relay is the name given to the protection, whose action depends on the distance of the feeding point to the fault. Teaching distance relay using matlabsimulink graphical user. Aug 31, 2018 for distance protection now a day quadrilateral characteristics is used. Pdf behavior of different distance relay characteristic on lines fed. In the preceding chapter, we examined relays in which one current was balanced against another current, and we saw that the operating characteristic could be expressed as a ratio of the two currents. If the measured impedance is less than the reach point impedance, it is assumed that a fault exists on the line between the relay and the. Over the years, different methods have been adopted to test the characteristics, reach and maximum torque angle of a distance relay as part of acceptance testing.
Istance relays perationdepend on the agnitude of the current or ltage of the circuit. There is no sharp dividing line between areas of application where one or another type of distance relay is best suited. Fault resistance is ignored in 37, but it is also an important factor for distance relays in distribution systems, as distribution feeders are short in length and most faults are of high impedance characteristics. Digital relays, distance relay model, real time digital simulator, capacitive. Generally, directional elements are not applied alone, although they can be in unique applications. The time which elapses between the instant when the actuating quantity becomes less than the reset value to the instant when the relay contacts returns to its normal position. Op am p circuits can be designed to implement filter, summation, and comparison functions to name a few. Principles and characteristics of distance protection.
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