Zone-1 is meant for protection of the primary line. Zone-1 provides fastest protection because there is no intentional time delay associated with it. Operating time of Zone-1 can be of the order of 1 cycle. Zone 1 does not cover the entire length of the primary line because it is difficult to distinguish between faults which are close to bus B like fault at F1, F2, F3 and F4. In other words, if a fault is close to bus, one cannot ascertain if it is on the primary line, bus or on back up line.
This is because of the following reasons:. See the picture below. As clear from the picture above, if the reach of Zone-2 of a relay R1 is extended too much, then it can overlap with the Zone-2 of the relay R3. Under such a situation, there exists following conflict. If the fault is on line BC and in Z2 of R3relay R3 should get the first opportunity to clear the fault.
Calculate IDMT over Current Relay Setting (50/51)
Unfortunately, now both R1 and R3 compete to clear the fault. This means that Z2 of the relay R1 has to be further slowed down. As Zone-2 protection already have a time delay, due to overlapping we need to further introduce some time delay which will degrade the performance of Relay for Zone Hence, a conscious effort is made to avoid overlaps of Z2 of relay R1 and R3.
Thank you! Your email address will not be published. Notify me when new comments are added. This site uses Akismet to reduce spam. Learn how your comment data is processed. Subscribe to our mailing list and get interesting stuff and updates to your email inbox. There are infeed and outfeed effects associated with working of distance relays.
E Electrical. Membership No:M He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. Since it is energy it is always consist of Power P which equal with current I and consist of t time. Whereas high over current setting is to limit short circuit withstand. Setting high over current setting shall be wise to distinguish between real short circuit and starting current.
Hello sir, I am not clear with this explanation, can you explain with some example. But i have noticed that at some places SQ.
Does HT cable selection is related with fault level and HT cable at 11 kv should not be used less than Sq. For HT Cable one important criteria which need to be consider is Short circuit level. Normally 11KV S. C level is 20 to 25KA at it varies according to Electricity provider company. C falls in 17 to 20KA. For HT cable you have to consider S. C level of utility first than Current carry capacity of Cable. Please let me know the details of selection of Neutral grounding resistance.
Your suggestion please. Dear K. F is better to make it less or equal 1 ,it means always lagging. We are going to synchronize 30MW,11kv DG with this grid breaker. Power failure time, I wish to isolate grid feeder. Please advice. Sir, thank u for your notes on Normally inverse curve. By the same way plz give the formula for Extermly inverse curve. You may assume any capacity of transformer installed in the outgoing feeder in above example. Sir, I would like to known how relay can be wiried and implemented and settings and how its configured in relay panel.
And i had a doubt, this realy implementation and configuration and setting are different from one another??????Michael J. Thompson and Daniel L. Heidfeld, Schweitzer Engineering Laboratories, Inc.
Some conditions are alternate normal, not contingencies You must identify contingencies appropriate for check at hand. Lines are typically not physically balanced Short lines have more error for an out-of-zone fault Underreaching elements must never overreach Overreaching elements must never underreach. Phase Distance Pilot Tripping Zone Number of relay elements is limited Step Zone 2 or Step Zone 3 can be reused as pilot tripping zone Independent distance element can be used for more freedom in setting reach.
Zero-sequence impedance is known with less precision Can be difficult to find worst-case mutual coupling effect Fault resistance can cause overreach. Same as for phase distance Recheck using ground faults because 3I0 will have different distribution than phase current. Ground Overcurrent Most uncertainty in zero-sequence network Higher zero-sequence line impedance High fault resistance possible Speed dichotomy.
Impedance-Based Directional Element Element measures source impedance to fault For reverse faults, impedance is in front of relay. Pilot tripping or pilot blocking pickups are below default current thresholds A pilot scheme is used and CTRs are different at each terminal You are protecting series-compensated or three-terminal lines.
Summary Determine if cookbook settings can be applied to protected line Calculate appropriate security and dependability limits Know when to not use AUTO directional settings Use thorough documentation to record your reasoning. Learn more about Scribd Membership Home.Distance Protection Relay setting
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Jump to Page. Search inside document. Thanigaivelan Govindhasamy. Book Lover. Nadeem Khalid. Bhuvanes Waran.Siemens Ltd. Offenders are liable to the payment of damages. All rights are reserved in the event of the grant of patent or registration of a utility model or design. Line per unit Length X refered to sec. Largest line at the Remote StationPrimary value As the transformer capacities are variable the reach is as calculted from the above 8. Reactive direction are set so that the inner characteristic covers completely all the distance protection zones,which are to be blocked by the PSD function.
Operating mode of time delayed trip for the distance protection zone 1 for ph-ph faults. Operating mode of time delayed trip for the distance protection zone 1 for ph-E faults.
Operating mode of time delayed trip for the distance protection zone 2 for ph-ph faults. Settings of Phase to earth element Operation of distance protection zone 2 for Ph-E faults.
Operating mode of time delayed trip for the distance protection zone 2 for ph-E faults.
Distance Relay Setting calculation
Operating mode of time delayed trip for the distance protection zone 3 for Ph-Ph faults. Operating mode of time delayed trip for the distance protection zone 3 for Ph-E faults Time delayed trip operation of the distance protection zone 3 for Ph-E faults Manual energising time.
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W-0 Document no. T Ratio P.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. The apparent impedance so calculated is compared with the reach point impedance.
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 reach point. The reach point of a relay is the point along the line impedance locus that is intersected by the boundary characteristic of the relay. The loci of power system impedances as seen by the relay during faults, power swings and load variations may be plotted on the same diagram and in this manner the performance of the relay in the presence of system faults.
Traditional distance relays and numerical relays that emulate the impedance elements of traditional relays do not measure absolute impedance. They compare the measured fault voltage with a replica voltage derived from the fault current and the zone impedance setting to determine whether the fault is within zone or out-of-zone.
Relay measuring elements whose functionality is based on the comparison of two independent quantities are essentially either amplitude or phase comparators. For the impedance elements of a distance relay, the quantities being compared are the voltage and current measured by the relay.
There are numerous techniques available for performing the comparison, depending on the technology used. They vary from balanced-beam amplitude comparison and induction cup phase comparison electromagnetic relays, through diode and operational amplifier comparators in static-type distance relays, to digital sequence comparators in digital relays and to algorithms used in numerical relays.
Operation occurs for all impedance values less than the setting, that is, for all points within the circle. The relay characteristic, shown in Figure It is to be noted that A is the relaying point and RAB is the angle by which the fault current lags the relay voltage for a fault on the line AB and RAC is the equivalent leading angle for a fault on line AC.
Vector AB represents the impedance in front of the relay between the relaying point A and the end of line AB. Vector AC represents the impedance of line AC behind the relaying point. This is achieved by the addition of a polarising signal.
Mho impedance elements were particularly attractive for economic reasons where electromechanical relay elements were employed.
As a result, they have been widely deployed worldwide for many years and their advantages and imitations are now well understood. For this reason they are still emulated in the algorithms of some modern numerical relays. This demonstrates that the impedance element is inherently directional and such that it will operate only for faults in the forward direction along line AB.Distance protection is a non-unit system of protection offering considerable economic and technical advantages.
Unlike phase and neutral over current protection, the key advantage of distance protection is that its fault coverage of the protected circuit is independent of source impedance variations. Let us take an example of this to understand how distance protection is independent of source impedance.
Consider the figure below. In the figure above, R1 is an over current relay which is used for the protection of Transmission Line. If there is a fault at F1. Therefore the setting of over current Relay should be more than Now consider the case.
Distance Setting Excel
Here fault is not on the Transmission Line but it is assumed to be inside Switchyard and only one source is feeding the power to the network. Proceeding in the similar manner. Distance protection is therefore used for the protection of Transmission Line. It is simple to apply and fast in isolating the faulty section from the healthy network. Distance Protection provides primary as well as back-up protection to the protected line. I will show this back-up protection function latter in this post.
Since the impedance of a transmission line is proportional to its length, for distance measurement it is justified to use a relay capable of measuring the impedance of a line up to a predetermined point. This predetermined point is called Reach of the Relay.
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. The basic principle of distance protection involves the division of the voltage at the relaying point by the measured current.
The apparent impedance so calculated is compared with the reach point impedance which is settable in the Relay. Consider the figure below and carefully observe. Here there are three sub-stations namely A, B and C. For sub-station A, the distance protection is divided into three zones Z1a, Z2a and Z3a which are called Zone-1, Zone-2 and Zone-3 protection. Similarly for sub-station D the three zones will be Z1d, Z2d and Z3d. It should be noted that all Zones are setting is done in terms of impedance.
Will it be???? Which means if the distance Relay senses Impedance less than Assume the Longest Line from substation B is having an impedance of 61 Ohm. Which means if the distance Relay senses Impedance less than 41 Ohm then it will pick-up for ZoneSource impedance angle in deg 3 Angle in radians 4.
Positive Sequence Resistance at local end, in ohms Positive Sequence Reactance at local end, in ohms Positive Sequence Resistance at remote end, in ohms Positive Sequence Reactance at remote end, in ohms. Positive Sequence Reactance in ohms The GFC can be operated in two modes - the under impedance mode and the over current mode. In the under impedance mode, the GFC characteristic should, in general, cover all the impedance measuring zones used for distance protection, regardless of their directionality.
Normally set to 2 times of zone-3 with a limit on the resistive direction so that the characteristics does not enter the load area.
Load Impedance primary Load impedance secondary. Power Swing Block Function The reach of the Inner characteristic in the resistive and reactive direction are set so that the inner characteristic covers completely all the distance protection zones, which are to be blocked by the PSD function.
Understanding Distance Protection Relay
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