From current setting we calculate the trick current of the relay. The electrical quantity may be voltage or current. Transformer Differential Relay testing | and | how to create slope on Omicron kit | RET ABB RELAY - Duration: 34:03. Magnitude restraint bias is used to ensure the relay is stable when the transformer is carrying load current and during the passage of through (out of zone) fault current. Scope. 1.2 Circulating Current High Impedance Protection 1.2.1 General information of High Impedance Protection Schemes In contrary to the low impedance differential protection schemes, where each of several CTs forming differential protection zone is directly connected to a separate relay input, the high impedance protection So far we have discussed about the principles of transformer differential protection. Relay-setting calculations are less complex than with a high-impedance scheme. Using a CT ratio of 240, the TAP setting value is 3.45Amps secondary for the wye side. Consider a single line-to-ground through fault as shown on the figure below. The considerations in setting slope 1 and slope 2 were presented in our first article for transformer differential protection. The SEL-487E Transformer Differential Relay provides three-phase differential protection for transformer applications with up to five three-phase restraint current inputs. The transformer MVA rating is 33MVA while the voltage rating is 23kV. Reply. This means that our transformer differential protection is well within the no operate zone. These compensated current values are used in the calculation of the operate and restraint currents and are evaluated based on the percent biased differential characteristic. Enter your email address to subscribe and receive notifications of new posts by email. A transformer differential relay for a 3-winding transformer from Schneider Electric has been used. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Current inputs for the high voltage side are wired as usual into input A. i am currently work on commissioning testing of transformer bias differential CRP. Next we define the percentage biased differential characteristic through the settings minimum operate pick-up, slope 1, slope 2, slope boundary, and unrestrained current pick-up. We started with the introduction into Percentage Biased differential were we talked briefly about operate and restraint current, and slope characteristic. Then we discussed about how CTs are actually connected to relays. 2 / 10. generator protection wordpress com. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. Go back to contents ↑ 2. Next on the setting is TAP compensation which is based per unit concept. Can be overcome with proper setting of O/C relay 2- Occurs when carrying large outside through fault currents with dc components This is the main cause of instability (malfunction) of the relay during external fault . website. Protection systems applied to these may be broadly classified as unit and non-unit protection systems. Understanding these concepts are very important in carrying-out a transformer differential protection calculation. Let us examine the response of our transformer differential protection on through fault conditions. prospect retrospect lntebg com. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. In our article, The Operate Quantity, we calculated the minimum operate pick-up, 0.28, based on the CT error and voltage ratio variation. Take note that other settings not discussed here were left to their default relay values. Use the three independent restricted earth fault (REF) elements for sensitive ground-fault detection in grounded wye-transformer applications. The engineer must balance the expense of applying a particular protection scheme against the consequences of relying on other protection or sacrificing the transformer. Omicron CMC256 or 356 Test Equipment or Any Equivalent To Be Used. The input will be the relay settings, and it should be capable of calculating Ida, Idb, Idc and Ira, Irb, Irc under any combination of injected phase currents, for any vector group of the transformer . A recommendation for the selection of current transformers is also given. The first knee-point depends on the setting at ‘DIFF: Idiff>’ of MICOM P634 relay and is on the intersection with the tripping characteristic for single-side feed. Not as sensitive as the high-impedance scheme (as will be shown shortly); The scheme circuitry is more complex than that of a high-impedance scheme. System stability, reclosing, and load shedding. (1) Differential Current Threshold: Is1 (3) Bias current threshold: Is2 (2) Lower Percentage Bias Setting: K1 (4) Higher Percentage bias setting: K2 1.1 Fft Fast Fourier Transform technique is used for preventing the maloperation. We use to prefer current based differential protection, but […] November 19, 2020 at 11:21 am on your email . We will apply wye connected CTs on both sides of the transformer. E.g. Available at https://selinc.com. Other similar relays use similar concepts through the actual terminology could be different. generator protection wordpress com. RET615 is a dedicated transformer protection and control relay for protection, control, measurement and supervision of power transformers, unit and step-up transformers, including power generator-transformer blocks, in utility and industrial power distribution systems. 6 Differential Protection with REF 542plus 1MRS 756281 Feeder Terminal 2. Please share your thoughts in the comments section below. relay setting electrocon. See our User Agreement and Privacy Policy. But mostly voltage based relays are not preferred. mis operation cases on transformer differential protection. SEL recommends compensating on the wye side. In this article, we will present a discussion on transformer differential protection calculation through an application example. This setting should be larger then the transformer magnetizing cur-rent and steady state CT errors during no load conditions. See our Privacy Policy and User Agreement for details. Substations Sitemap Test Formats Manuals Software Transformer Vector Group and CT to Relay Connection. Differential Relays 2. This technical article will cover the gathering of information needed to calculate protective relay settings, the setting calculations for the various protective functions, typical generator/turbine withstand times for abnormal operating conditions, and the math associated with various types of impedance elements. By applying the phase and tap compensation setting, the currents values are as presented. BUY UNLOCK VERSION($) Calculate Size of Circuit Breaker on Primary … Setting procedures are only discussed in a general nature in the material to follow. Clipping is a handy way to collect important slides you want to go back to later. For this example, we have a 25/33MVA 69/23kV Delta-Wye Transformer with vector group, Dyn1. Based on our discussion on CT and relay connection, we apply CT compensation on the 23kV side using. If we take the slope of the operate and restraint currents, we will get a value very close to zero. ABB RED670 Fault Locator Calculations. The complete settings for the percentage biased differential characteristic is presented below. 87BD Initial Setting: This is the minimum level of differential current at which the relay will operate. Index Terms — Current Differential Protection, Power Transformer, Protection Relay, Single Phase I. Connection of Differential Relay to delta-wye transformer, phase shift, CT ratio ... Transformer protection (differential, sudden pressure, over temperature, low oil, etc). It shall include two sets of current restrain inputs for each winding. The references provide a source for additional theory and application guidance. This setting also compensates for zero sequence currents as was discussed in our article on Zero Sequence Compensation. If … For that, we have to first divide primary faulty current by CT ratio to get relay faulty current. 3 : Model setting calculations-Transformer 1-132 4 : Model setting calculations- Shunt Reactor 1-120 5 : Model setting calculations- Busbar 1-15 6 : Relay setting guide lines for transmission lines 1-19 7 : Recommendations for protection system management 1-5 8 : Check list for audit of fault clearance system 1-16 9 : Details of protection audit 1-5 . Reply. transformers, and how the protection setting calculations and actual relay settings are affected when protecting three single-phase transformers. Lastly, we talked about zero sequence and tap compensation and how they affect the operation of the transformer differential protection. If you continue browsing the site, you agree to the use of cookies on this website. Cream Magazine by Themebeez, Basic Transformer Differential Protection Calculation, Application Example on Transformer Differential Protection Calculation, 25/33MVA 69/23kV Delta-Wye Transformer on SEL-387A Relay, Differential Protection Relay: Average Scaling, Compensating CT Ratio Mismatch | Differential Protection, Vector Group of Transformer Dyn1|Dyn11|Ynd1|Ynd11, Introduction to Basic Overcurrent Protection and Coordination Study, kAIC Rating of Circuit Breakers | Calculation in Low Voltage System. Percentage differential relay or Biased Differential Protection: Generally differential protection relay means the relay operates when the phasor difference between the two or more electrical quantities exceed the pre-set value. Protection Engineer. Unit systems bounded by CT locations. With modern numerical transformer differential relays all above compensations are provided in the relay software. the relay setting parameters. Application Example on Transformer Differential Protection Calculation 25/33MVA 69/23kV Delta-Wye Transformer on SEL-387A Relay Figure 1. Next we revisited the concept of transformer vector groups and identified the key take away which is “Master the Delta Connection and you’re on your way to mastering Vector Groups!”. I need an excel sheet for the transformer differential protection relay RET615. Calculation of differential and restraining currents: The tripping characteristic of the Micom P634 relay differential protection device has two knee points. bus, generator, transformer, transmission line, capacitor, motor, etc. The currents seen by the relay are affected by the CT ratio and connection hence the values of the secondary currents before compensation. Delta side TAP setting value can be calculated using a CT ratio of 80. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. relay settings and the selec tion of current transformers are described with examples. Looks like you’ve clipped this slide to already. Calculate Differential Protection Relay setting: Calculate Percentage Differential Current at Normal tapping; Calculate Percentage Differential Current at Highest tapping ; Calculate Percentage Differential Current at Lowest tapping (25) Size of Transformer’s Circuit Breaker & Fuse (As per NEC 450.3) FREE DOWNLOAD. Transformer differential protection settings. In this application, we set the minimum operate pick-up to 0.3. heavy external fault. 2.1 Differential Relay Settings Calculations MiCOM P63X Relay Type: MICOM P63X Required Data Ratings of the Power and Current Transformers MVA Voltage Ratio Rated Voltage in kV (HV Side) Rated Voltage in kV (LV Side) Vector Group CT Ratio (HV Side) CT HV Side Vector Group CT Ratio (LV Side) CT LV Side … KEYWORDS: differential protection, transformer protection, motor protection. Protective relay functions and data. In SEL relays, this is represented by the setting CTC(1). The TAP setting compensation is automatically calculated in SEL relays by providing the appropriate transformer parameters and CT ratio. Thus we see that because of the above reasons a differential current will flow through the Differential Protection Relay. protective relay calculations and settings pcsbr com. We will start the transformer differential protection calculation with the identification of the transformer vector group. Reply. Sheet2 WnCTC Settings ReadMe Transformer Phase Transformer + CT Phase W1CTC = W2CTC = Degrees W3CTC = W4CTC = Winding 1 Winding 2 CT 1 CT 2 Winding 3 CT3 CT4 Winding 4 Reference Winding Then click START. SEL787 and SEL 387/587 Transformer differential relay is used for this discussion. Copyright © All rights reserved. Disadvantages of biased scheme’. The combination of operate and restraint currents are reflected on the transformer differential characteristic curve as show below. Differential Protection Scheme basic and 5MVA Transformer(OLTC) Protection Calculation Published on May 15, 2018 May 15, 2018 • 126 Likes • 6 Comments DIGSI 5. minimum ijser. Protection for two-winding power transformers including differential protection; Production benefits. SEL Transformer Differential Winding Compensation Settings Calculator. May 23, 2019 at 1:20 pm This ... motor protection relay setting calculations, stuck up at relay/motor curve (hot/cold)? Fatima. Line protection (directional comparison, blocking, unblocking, transfer trip, etc). In this video we have explained calculation for IDMT over current relay setting calculation. Transformer differential protection The IED shall include a transformer differential protection function, with a biased operate/restrain character- istic, internal CT ratio matching, vector group compensation and settable zero sequence current elimination. Say current setting of the relay is 150 % therefore pick up current of the relay is 1 × 150% = 1.5 A. Step-3 Now we have to calculate PSM for the specified faulty current level. That’s it for our discussion on basic transformer differential protection calculation. Some of the parameters relevant to this discussion are: These quantities are calculated as follows. Er. We will start the transformer differential protection calculation with the identification of the transformer vector group. For the LV side the secondary currents from the CT are first wired to the input B and then in series through the input C for the third winding of the 3-winding relay. Introduction The three-phase differential protection incorporated in … If the transformer is used with an off nominal tap, then differential currents will arise as the CT ratio calculated for a particular Tap (Nominal Tap) will be different for different Tap, even under healthy conditions. Refer to specific instruction manuals for your relay. Click the appropriate Winding connections, CT connections, Phase Rotation, and Reference Winding settings… SEL-387A Instruction Manual. If the phase shift setting is entered incorrectly (30 degrees) and the test currents shown in figure 5(b) are entered, the transformer differential relay calculated quantities clearly show a problem (figure 8): the differential current magnitudes are not 0 for phases B and C and the relay trips. IOP is calculated as the vector addition of primary and secondary currents whereas IRT use…