Differential Relays 2. the client want to test a lot of test points, and scenarios, eg. SEL Transformer Differential Winding Compensation Settings Calculator. In this application, we set the minimum operate pick-up to 0.3. 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. This setting should be larger then the transformer magnetizing cur-rent and steady state CT errors during no load conditions. Thus we see that because of the above reasons a differential current will flow through the Differential Protection Relay. The TAP setting compensation is automatically calculated in SEL relays by providing the appropriate transformer parameters and CT ratio. 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. 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. (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. May 23, 2019 at 1:20 pm This ... motor protection relay setting calculations, stuck up at relay/motor curve (hot/cold)? Omicron CMC256 or 356 Test Equipment or Any Equivalent To Be Used. Transformer Differential Relay testing | and | how to create slope on Omicron kit | RET ABB RELAY - Duration: 34:03. Transformer differential protection settings. A recommendation for the selection of current transformers is also given. Calculation of Over Current Relay Setting: (1) Low over Current Setting: (I>) Over Load Current (In) = Feeder Load Current X Relay setting = 384 X 125% =480 Amp; Required Over Load Relay Plug Setting= Over Load Current (In) / CT Primary Current; Required Over Load Relay Plug Setting = 480 / 600 = 0.8 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. 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. Reply. 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!”. Available at https://selinc.com. Calculation of differential and restraining currents: The tripping characteristic of the Micom P634 relay differential protection device has two knee points. 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. transformers, and how the protection setting calculations and actual relay settings are affected when protecting three single-phase transformers. power system protection manual klipsch school of. We use to prefer current based differential protection, but […] The considerations in setting slope 1 and slope 2 were presented in our first article for transformer differential protection. relay settings and the selec tion of current transformers are described with examples. Unit systems bounded by CT locations. Looks like you’ve clipped this slide to already. Other similar relays use similar concepts through the actual terminology could be different. Using a CT ratio of 240, the TAP setting value is 3.45Amps secondary for the wye side. See our Privacy Policy and User Agreement for details. We will start the transformer differential protection calculation with the identification of the transformer vector group. Copyright © All rights reserved. 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 . IOP is calculated as the vector addition of primary and secondary currents whereas IRT use… Lastly, we talked about zero sequence and tap compensation and how they affect the operation of the transformer differential protection. 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. The references provide a source for additional theory and application guidance. the relay setting parameters. KEYWORDS: differential protection, transformer protection, motor protection. The engineer must balance the expense of applying a particular protection scheme against the consequences of relying on other protection or sacrificing the transformer. Line protection (directional comparison, blocking, unblocking, transfer trip, etc). 2 / 10. generator protection wordpress com. So far we have discussed about the principles of transformer differential protection. Fatima. System stability, reclosing, and load shedding. By applying the phase and tap compensation setting, the currents values are as presented. bus, generator, transformer, transmission line, capacitor, motor, etc. If we clear the concept for these relays first then understanding the Numerical Relay settings becomes easy. nk. We started with the introduction into Percentage Biased differential were we talked briefly about operate and restraint current, and slope characteristic. Connection of Differential Relay to delta-wye transformer, phase shift, CT ratio ... Transformer protection (differential, sudden pressure, over temperature, low oil, etc). SEL recommends compensating on the wye side. Protection for two-winding power transformers including differential protection; Production benefits. Please share your thoughts in the comments section below. The electrical quantity may be voltage or current. 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. Take note that other settings not discussed here were left to their default relay values. In this video we have explained calculation for IDMT over current relay setting calculation. 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 . Other relay settings are listed below. Sample calculation-for-differential-relays 1. Application to a two-winding transformer. Protective relay functions and data. i am currently work on commissioning testing of transformer bias differential CRP. generator protection wordpress com. PSM and TMS settings that is Plug Setting Multiplier and Time Multiplier Setting are the settings of a relay used to specify its tripping limits. From current setting we calculate the trick current of the relay. minimum ijser. A transformer differential relay for a 3-winding transformer from Schneider Electric has been used. mis operation cases on transformer differential protection. Go back to contents ↑ 2. Scope. 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. 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. 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. The complete settings for the percentage biased differential characteristic is presented below. differential relay electrical4u com. 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 Reply. The operate and restraint currents calculated are 0.01 and 4.28, respectively.