This Is The Test Procedure For Siemens 7ut61 Relay.docx

This is the test procedure for Siemens 7UT61 Relay (IEC61850 supported numerical relay). Omicron CMC256 or 356 Test Equipment or Any Equivalent To Be Used. Following parameters define differential characteristics: Setting in our example Pickup value of differential current = 0.2 I/In0 Slope 1 of tripping Characteristic = 0.25 Base point for slope 1 of charac = 0 Slope 2 of tripping characteristic = 0.75 Base point for slope 2 of charac = 2.5 I-RESTRAINT for start detection = 0.1 I/In0 Pickup vale of high set trip = 4.0 I/In0 1. Test Procedure for Checking of first branch: Objective: To test the sensitivity threshold of the differential protection which considers constant error currents such as magnetizing currents (I-DIFF>). Test method : -.Inject balanced currents in all phases. (Below the pickup value for fault detection (I-RESTRAINT). - Gradually increase currents till relay operation. - Note down the pickup value. Pass criteria : Characteristic equitation for this branch: (Basepoint1) ≤ ISTAB ≤ (IDIFF /m1) The operating current should be within +/- 5% of set value. 2. Test Procedure for Checking of second branch: Objective: To check slope m1, this considers current proportional errors result from transformation errors of the main CTs or the input CTs of the protection relay, mismatching and influence of tap changers in transformers. Test method: Simulate differential and stabilizing currents such that they lie in the first region over and under the curve. Stabilizing current ISTAB= │I1│+ │I2│ (Algebraic Summation) Differential current IDIFF = │I1 + I2│ (Vectorial Summation) Inject 1 A balanced current in HV and LV windings. Gradually increase HV current till relay operation. Note down value. Pass criteria : Characteristic equation for this branch: (IDIFF /m1) ≤ ISTAB ≤ (1/IDIFF)

Id = m1(ISTAB – Basepoint1) In our case , m1 = 0.3 Idiff> = 0.2 Please note that “IIDFF” and “ISTAB” are derived by the relay after amplitude and vector group matching. Hence, we have to multiply injected currents by amplitude matching factors for calculation of “IIDFF” and “ISTAB”, then we substitute this value of “ISTAB” into characteristic equation, To find Theoretical value of “IIDFF”. Then compare with measure value of “IIDFF”. 3. Test Procedure for Checking of third branch: Objective: To check slope m2, this provides additional restraint for high currents which may give rise to CT saturation. Test method: Simulate differential and restraining currents such that they lie in this region over and under the curve Stabilizing current ISTAB= │I1│+ │I2│ (Algebraic Summation) Differential current IDIFF = │I1 + I2│ (Victorian Summation) Inject 5 A balanced currents in HV and LV windings. Gradually increase HV current till relay operation. Note down value. Pass criteria: Characteristic equation for the branch: (1/IDIFF) ≤ ISTAB ≤ (1/m2 [Idiff>> - m1/IDIFF>] + 1/IDIFF>) Id = m2 (ISTAB – Basepoint2) In our case, m1 = 0.3 M2 = 0.75 Idiff> = 0.2 Please note that “IIDFF” and “ISTAB” are derived by the relay after amplitude and vector group matching. Hence, we have to multiply injected currents by amplitude matching factors for calculation of “IIDFF” and “ISTAB”, and then we substitute this value of “ISTAB” into characteristic equation, To find Theoretical value of “IIDFF”. Then compare with measure value of “IIDFF”. However, this is a manual & tedious process. This method requires time, effort & knowledge about the measuring algorithm of the relay. Due to advance in relay testing kit, relay testing software & relay software, the easy & convenient method for testing is as follows: 1. 2. 3. 4. 5.

Extract the .rio or .xrio file of the relay using relay software. Import the .rio or .xrio file in the differential module of omicron 356 testing kit software. Alternatively, open the PTL file from omicron library in of omicron 356 testing kit software and enter all the relevant settings from relay. Differential characteristics cure will be drawn based on above information by the omicron 356 testing kit software. Start testing by selecting various point on slope characteristics. Save the result and test reports for future reference.