Practical experience in setting transformer differential inrush restraint 63 1. When primary current both ends are the same, have identical turns ratios and no saturation then, i21p i21q. Technical guide protection criteria for medium voltage. Operating time, sensitivity, dependability and security requirements are examined for typical applications. Power transformer differential relay inrush restraint. The only difference between them is the restraining coil. Principles of differential relaying current balance high impedance determine worst case throughfault current. Date code 20001220 manual change information iii sel3875, 6 instruction manual revision date summary of revisions 991029 updated appendix a.
Sel transformer differential winding compensation settings calculator subject. The differential protection relay is used for the protection of the generator, transformer, feeder, large motor, busbars etc. Misoperation cases on transformer differential protection. A recommendation for the selection of current transformers is also given. How to test a transformer differential relay slope, high sets. Selwa05010w wiring harness for sel501 and sel587 connectorized relays, features new shorting connector. The lower slope provides sensitivity for internal faults. Explain challenges of transformer differential protection understand need for tap, phase, and zerosequence compensation and how they work understand how transformer differential relays are made secure for inrush and overexcitation transformer differential protection presentation objectives.
In addition to this, a thermal replica is integrated for the supervision of the thermal losses in the plant. Besides the threephase stabilized current differential function featuring 2nd and 5th harmonic restraint, the basic version terminals incorporate threephase overcurrent, nondirectional earthfault, restricted earthfault, transformer thermal overload and phase unbalance protection. The relays used in power system protection are of different types. Abstract the second harmonic inrush restraint function of transformer differential relays maintains security of the differential protection during transformer inrush events. Product guide ret615 transformer protection and control. Factory setting switch defaultoptions comments 5 heat pump systems cont. Page 1 sel387a timeovercurrent elements the sel387a provides numerous overcurrent elements, as many as 11 per winding and 5 per neutral input.
The percentage differential relay is defined as the relay that operates on the phase difference of two or more similar electrical quantities. Four levels of phase instantaneous or definitetime elements are available for overcurrent protection, breaker failure protection, overcurrent phase selection for targeting, transformer backup protection, and so on. Addendum this addendum contains information that relates to the l90 line differential relay relay, version 3. Moreover, harmonics detection is implemented to obtain inrush current stabilization. Dual slope transformer differential relay cr4 discussion. Sel transformer differential winding compensation settings calculator other titles. Some of the supported functions in ret615 must be added with the application configuration tool to be available in the signal matrix tool and in the relay. It is also possible to change the menu structure by moving variables from one menu to another see moving program variables. Set the differential elements with either a single or dualslope percentagerestraint differential characteristic, as shown below. The protection relay can be parameterized for use with threephase and singlephase transformers.
This technical report refers to the electrical protections of all 2kv switchgear. How to test a transformer differential relay slope, high. It is the advanced form of differential protection relay. Medium voltage products technical guide protection criteria. Among them differential relay is very commonly used relay for protecting transformers and generators from localised faults. The typical setpoint for the second harmonic restraint is the relay manufacturers default. Sel transformer differential winding compensation settings calculator description. Generator and motor diff are included where applicable. Siprotec 7ut5125 transformer differential protection relay. Omicron cmc256 or 356 test equipment or any equivalent to be used. Differential relay setting argus 7sr242 cr4 discussion.
The specific application can be chosen by parameterization. Thus, it can be quite tricky to test a numerical transformer differential relay by secondary injection in order to verify that the relay is set properly to protect transformer in a particular. Pilot wire relay commonly, the most sensitive setting 10 20 % of nominal current is applied and even recommended without any consideration of actual fault current levels for the application. Selection of the protection system for machines and plants. Basic setting of current differential line protection eep. We will start the transformer differential protection calculation with the identification of the transformer vector group. Current transformers and relay connections, as well as computation of transformer setup settings with standard and nonstandard phase shift are. Factory setting switch defaultoptions comments 5 notes heat pump systems 1 if batteries are installed the 24 volt ac common connection is optional.
The higher slope provides stability under through fault conditions, since transient differential currents may be. Pick up current current setting plug setting multiplier. Application example on transformer differential protection calculation 2533mva 6923kv deltawye transformer on sel387a relay figure 1. The time setting dial is calibrated from 0 to 1 in steps of 0. By default, the frequency of the currents emulated by the internal relay test system during. The factory default menu structure for all of the available variables is shown in the below table. Based on the user selections in the setup menu, some of the variables may not be visible. Installation added a caution about replacing the battery page 217 affecting subsequent pagination. In case of wire break or supply failure, the supervision relay releases and closes contacts 31 32. In this type of relay, there are restraining coils in addition to the operating coil of the relay. Eq 1 otherwise in most application cases, the setting can be left at the default sensitive value of 0. Principle of percentage restrained differential protection. The sel710 motor protection relay provides an exceptional combination of protection, monitoring, control, and. Protection relays differential relays 2 using biased relay.
It is also recommended to use the factory default for the setting. Cts having the same ratio are installed in all the connections to the component example transformer to be protected and the secondary of the cts are connected in parallel to the relay. Oct 06, 2016 transformer differential calculation 1. By internal electronics the pilot lines are supervised for wire breaks. Criteria for the setting and testing of transformers differential relays was presented. Protection selectivity is partly considered in this report, and could be also revaluated. The following are the classification of the differential protection relay. Basic transformer differential protection calculation. Basic transformer differential protection calculation pac. Jun 23, 2018 this is the test procedure for siemens 7ut61 relay iec61850 supported numerical relay. In the differential relay scheme circuit, there are two currents come from two parts of an electrical power circuit.
Differential protection with ref 542plus feeder terminal. Transformer vector group and ct to relay connection. Siprotec 7ut5125 transformer differential protection. Sel transformer differential winding compensation settings.
So far by adjusting relay operating time, both of the factors to be adjusted. Transformer differential calculation linkedin slideshare. The setting of the inrush restraint on a perphase basis on the protected transformerwas performed. This adjustment is commonly known as time setting multiplier of relay. Current differential line protection setting considerations. This paper involves the study of power transformer differential relay inrush restraint settings. Temperature differential user option 1 and 2 the differential setting is the temperature control range that your thermostat will provide. The keypad for the terdt12 relay incorporates an 8 digit led display, a membrane keypad for programming, data entry and data retrieval. While setting parameters will differ depending on the type of current differential relay, the setting principles and system conditions to consider remain largely the same. Differential relaying provides selectivity by providing a zone of protection with a circuit of interconnected cts. Ret 670 required data ratings of the power and current transformers mva voltage ratio rated voltage in kv hv side rated voltage in kv lv side. These settings may be revaluated during the commissioning, according to actual and measured values.
Overcurrent relay setting model for effective substation relay coordination international organization of scientific research 27 p a g e associated with temperature rise of the equipment whose permissible limit is based on insulation class and material problems. This kind of differential protection is used for lines up to 1500 m. Motor differential protection schemes schneider electric. Figure 1 vamp 265 connected as a motor differential protection using 6 cts. Incorrect settings of transformer overcurrent protection the setting is either too. Sel587 current differential relay schweitzer engineering.
This is designed to response to the differential current in the term of its fractional relation to the current flowing through the protected section. It thus provides a means for maintaining a practically constant volumetric rate of flow regardless of variations of the process or supply pressures. The basic element in overcurent protection is the overcurrent relays. Practical experience in setting transformer differential inrush. Provide disconnect and overload protection as required. Notes heat pump systems 1 if batteries are installed the 24 volt ac common connection is optional. In addition to the differential function, a backup overcurrent protection for 1 wind. This is the test procedure for siemens 7ut61 relay iec61850 supported numerical relay. Motor differential protection schemes this application note applies to vamp 265, vamp 300 and wimo.
Keys reset resets the device after the conditions that cause an. Thus the relay current equals the difference of the respective magnetisation currents. Fault current flowing through saturated ct and associated wiring generates a voltage across the relayrscombination. In this way an optimal adaptation of the relay to the protected ob ject can be achieved. Relay settings calculations electrical engineering. Overcurrent relay setting model for effective substation. This paper involves the study of power transformer differential relay inrush restraint settings applications. The relay is delivered from the factory with default connections described in the functional diagrams for binary inputs, binary outputs, functiontofunction connections and alarm leds. The constant differential relay maintains a constant pressure drop across an internal needle valve for any flow setting up to about 2. Sel transformer differential winding compensation settings calculator. A differential current greater than zero indicates an internal fault condition. Two variants of the differential relay can be supplied. Medium voltage products technical guide protection.
Differential relay setting argus 7sr242 cr4 discussion thread. The use of standard transformer differential protection for such applications is considered. Transformer terminal ret 541 transformer protection and. Set taps on multirestraint relay work through matching taps in pairs be sure to use same mva base for each tap calculation setting taps for threewinding transformers. Aug 31, 2018 so far by adjusting relay operating time, both of the factors to be adjusted. Differential, restricted earth fault, thermal, and overcurrent. The differential relay is one that operates when there is a difference between two or more similar electrical quantities exceeds a predetermined value. High impedance differential relay highimpedance differential relays are typically used for bus protection. Current differential line protection setting consideration. Fault current flowing through saturated ct and associated wiring generates a voltage across the relay rscombination. Page 7 local pc relay setting the user can communicate with the grt100 from a local pc via the rs232c port on the relay fascia. Proper relay settings and the selec tion of current transformers are described with examples. Pdf differential protection for power transformers with non.
Practical experience in setting transformer differential. Dependin g on the sensitivity of the setting of the basic differential protection solution, i. Bus protection is an application that demands many sets of cts be connected to the relays. Differential relays are very sensitive to the faults occurred within the zone of protection but they are least sensitive to the faults that occur outside the protected zone.
While setting parameters will differ depending on the type of. Pdf easy method for testing transformer differential relays. Following parameters define differential characteristics. Principles of differential relaying setting a low z diff relay. With the ideal transformer of figure 1, and assuming ideal cts, the differential current is zero when current is flowing through the transformer.
This addendum lists a number of information items that appear in the instruction manual gek106445c revision f4 but are not included in the current l90 operations. The the user can input or change settings using the following data can be viewed or analysed on the local operation keys on the relay fascia or via a local or pc with rsm100 software. The relay whose operation depends on the phase difference of two or more electrical quantities is known as the differential protection relay. W1heat relay stage 1 w2heat relay stage 2 y1compressor relay stage 1 g fan relay c 24 volt ac transformer common note 1, 3 heat only or millivolt set installer switch to conv rh power connection w heat relay appears as w1e on 2220nc g fan relay note 4 c 24 volt ac transformer common note 1. Current setting is the setting of currentpickup current in a relay at which we want to operate that relay. Testing numerical transformer differential relays commissioning. While setting parameters will differ depending on the type of current differential relay, the setting principles and system conditions to. The ret 541 terminals are loaded with functionality to suit your application. Pdf differential protection methodology for arbitrary threephase. Nonprogrammable detailed thermostats installer guide. This differential protection is directionally secure and is simple to.
L90 current differential settings ge grid solutions. It works on the principle of comparison between the phase. The second knee of the tripping characteristic is defined by the setting is2. The smaller the setting, the tighter your range of temperature control and comfort will be. Type dth 31, 32 dttm 11, 12 high speed biased differential. Transformer differential relay highset differential current setting i diff i diff must be greater than maximum inrush current about 15 time transformer rating current harmonic stabilization inrush restraint ratio 2nd harmonic 12% i 2fni fn activate crossblock function relay setting criteria. Differential protection and distance protection selectivity. The adjustment of traveling distance of an electromechanical relay is commonly known as time setting. Differential and overcurrent elements, replaced irt1 with irt4 in discussion of differential element operation, page 32. It is also an application that demands the relay be able to operate with unequal ct performance, since external fault magnitudes can be quite large. For digital current differential line relays, the sound and simple setting principles utilized for pilot wire relays seem to have been forgotten. The sel387e relay has three differential elements that use operate and restraint quantities calculated from the two or threewinding input currents.
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