Schweitzer Engineering Laboratories SEL-251 Instruction Manual
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Schweitzer Engineering Laboratories SEL-251 Instruction Manual

Distribution relay; phase overcurrent relay with voltage control; negative-sequence overcurrent relay; ground overcurrent relay; multiple shot reclosing relay; selectable setting groups circuit breaker monitor; fault locator selogic control equations
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NEGATIVE-SEQUENCE OVERCURRENT RELAY
GROUND OVERCURRENT RELAY
MULTIPLE SHOT RECLOSING RELAY
SELECTABLE SETTING GROUPS
SEL
SCHWEITZER ENGINEERING LABORATORIES, INC.
2350 NE HOPKINS COURT
PULLMAN, WA USA 99163-5603
TEL: (509) 332-1890
SEL-251-2
SEL-251-3
DISTRIBUTION RELAY
PHASE OVERCURRENT RELAY
WITH VOLTAGE CONTROL
CIRCUIT BREAKER MONITOR
FAULT LOCATOR
™ CONTROL EQUATIONS
OGIC
INSTRUCTION MANUAL
FAX: (509) 332-7990
SEL-251

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Summary of Contents for Schweitzer Engineering Laboratories SEL-251

  • Page 1 NEGATIVE-SEQUENCE OVERCURRENT RELAY GROUND OVERCURRENT RELAY MULTIPLE SHOT RECLOSING RELAY SELECTABLE SETTING GROUPS CIRCUIT BREAKER MONITOR FAULT LOCATOR ™ CONTROL EQUATIONS OGIC INSTRUCTION MANUAL SCHWEITZER ENGINEERING LABORATORIES, INC. 2350 NE HOPKINS COURT PULLMAN, WA USA 99163-5603 TEL: (509) 332-1890 FAX: (509) 332-7990...
  • Page 2 All brand or product names appearing in this document are the trademark or registered trademark of their respective holders. Schweitzer Engineering Laboratories, Inc., SEL , and are registered trademarks of Schweitzer Engineering Laboratories, Inc. OGIC This product is covered by U.S. Patent Nos: 5,041,737; 5,477,408; 5,479,315; and 5,602,707.
  • Page 3 Added note to indicate that the Low-Level Test Interface is not available on LP chassis relays. Appendix B − Added note below Figure B.1 that describes the difference in test point locations for LP chassis relays. − Reissued all Appendices. Date Code 20000421 Manual Change Information SEL-251, -2, -3 Instruction Manual...
  • Page 4 Added Settings Sheets to end of Section 5. 971107 Section 2 - Corrected logic in Figure 2.22. 971028 Section 2 - Corrected Drawings in Figures 2.1 and 2.2. 970418 Appendix A - Added New Firmware Versions. Manual Change Information Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 5 SEL-251, -2, -3 INSTRUCTION MANUAL TABLE OF CONTENTS SECTION 1: INTRODUCTION SECTION 2: SPECIFICATIONS SECTION 3: COMMUNICATIONS SECTION 4: EVENT REPORTING SECTION 5: APPLICATIONS SECTION 6: INSTALLATION SECTION 7: MAINTENANCE AND TESTING SECTION 8: APPENDICES Appendix A: Firmware Versions in this Manual...

  • Page 7: Table Of Contents

    Fault Locator Reduces Line Patrol and Outage Time ............1-3 Analyze Operations Using Event Reports................1-3 Comprehensive Metering Supports Protection, Operation, and Demand Analysis ..... 1-3 Access SEL-251 Relay Information via the SEL-RD Relay Display........1-4 General Description: Plug-In Connector Model ................. 1-4 Wiring Harnesses ......................... 1-4 High Current Interrupting Output Contacts................

  • Page 9: Section 1: Introduction

    Initial Checkout Procedure in Section 7: Maintenance & Testing. VERVIEW Conventional Terminal Block Model The SEL-251 Relay is designed to protect distribution lines for all fault types. The following list outlines protective features, performance, and versatility gained when applying the SEL-251 Relay to your installations.

  • Page 10: Plug-In Connector Model

    ESCRIPTION ONVENTIONAL ERMINAL LOCK ODEL The SEL-251 Relay protects, controls, and monitors distribution feeders. It offers important new and unique features, like user-programmable SEL Control Equations, negative-sequence OGIC overcurrent elements, and selectable setting groups. The advanced relay design enhances security, reliability, sensitivity, and operation.

  • Page 11: Sophisticated Multiple-Shot Reclosing Relay Includes Reset Inhibit And Sequence Coordination

    Fault Locator Reduces Line Patrol and Outage Time The SEL-251 Relay includes a fault locator which uses fault type, prefault, and fault conditions to provide an accurate estimate of fault location without communications channels or special instrument transformers, or source impedance information, even during conditions of substantial load flow and fault resistance.

  • Page 12: Access Sel-251 Relay Information Via The Sel-Rd Relay Display

    Access SEL-251 Relay Information via the SEL-RD Relay Display You can connect up to four SEL-251 Relays to one SEL-RD Relay Display. Access relay target, meter, status, fault history, and circuit breaker information via the relay display. You can even change the active setting group via the display.
  • Page 13 Read-Only Memory ......................2-24 Analog-to-Digital Converter....................2-24 Master Offset........................2-24 Settings ..........................2-24 IRIG-B Input Description......................2-25 Signal Processing ........................2-25 Torque Control ........................... 2-26 External Torque Control..................... 2-26 Internal Torque Control...................... 2-27 Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...
  • Page 14 Figure 2.1: SEL-251 Relay Conventional Terminal Block Model Inputs, Outputs, and Targets Diagram ......................... 2-5 Figure 2.2: SEL-251 Relay Plug-In Connector Model Inputs, Outputs, and Targets Diagram ....2-6 Figure 2.3: Time Delayed 52A and 52B Functions................... 2-9 Figure 2.4: Trip Circuit Monitor (TCM) DC Voltage Connections ............2-9 Figure 2.5: Trip Circuit Monitor Alarm (TCMA) Logic ................

  • Page 15: Section 2: Specifications

    48 and 125 V (L/R = 40 ms) 250 V (L/R = 20 ms) Note: Do not use high-current interrupting output contacts to switch ac control signals. These outputs are polarity dependent. Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...
  • Page 16 Optoisolated Inputs The SEL-251 available input ratings are different for the three chassis types. The nominal input rating is not field adjustable - it is determined at the time of order, and is identical for all six inputs. The inputs are not polarity dependent.
  • Page 17 IEC 255-21-2 First Edition - 1988 Electrical relays, Part 21: Vibration, shock, bump, and seismic tests on measuring relays and protection equipment, Section Two - Shock and bump tests Severity Level: Class 1 Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...
  • Page 18 Severity Level: 4 (4 kV on power supply, 2 kV on inputs and outputs) Unit Weight SLP Chassis: 12 pounds (5.5 kg) - 5 amp nominal current inputs LP Chassis: 16 pounds (7.3 kg) - 1 amp nominal current inputs Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 19: Figure 2.1: Sel-251 Relay Conventional Terminal Block Model Inputs, Outputs, And Targets Diagram

    Figure 2.1: SEL-251 Relay Conventional Terminal Block Model Inputs, Outputs, and Targets Diagram Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...

  • Page 20: Figure 2.2: Sel-251 Relay Plug-In Connector Model Inputs, Outputs, And Targets Diagram

    Figure 2.2: SEL-251 Relay Plug-In Connector Model Inputs, Outputs, and Targets Diagram Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 21: Functional Specifications

    Element measures 3 I negative-sequence current • Pickup (50Q): 0.5 to 100 A ±3% of setting ±0.18 A secondary • Time delay: 0 to 16,000 cycles in 1-cycle steps • Externally torque controllable Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...

  • Page 22: Ground/Residual Overcurrent Elements For Ground Faults - See Figure 2.20

    The time delay pickup and time delay dropout settings (52APU and 52ADO, respectively) are provided to generate the 52AT and 52BT functions. The 52AT and 52BT bits can be used to supervise overcurrent elements for fuse saving and inrush conditions. Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 23: Trip Failure Timer Detects Breaker Failure Or Slow Trip - See Figure 2.24

    TCM input allows a few milliamperes of current through the trip coil. The volt- age drop is across the TCM input because the input has a much higher impedance than the trip coil. Date Code 20000421 Specifications SEL-251, -2, -3 Instruction Manual...

  • Page 24: Ogic

    In Figure 2.4, a 52A contact is connected to relay input 52A. You can connect a 52B contact instead. Wire a 52B contact to a relay input !52A to perform the 52A function. Input options 52AR or !52AR can also be used. (See SEL-251 Relay SEL Control Equations.)

  • Page 25: Assign Inputs To The Functions You Need

    Reclose initiation is provided by the assertion of the internal TRIP condition. When the TRIP condition drops out and the circuit breaker is open (per 52A or !52A), the open interval starts timing. Date Code 20000421 Specifications 2-11 SEL-251, -2, -3 Instruction Manual...
  • Page 26 Assert an input by applying control voltage to the corresponding rear panel input terminals. Control voltage polarity is not important. When a function is not assigned to an input, the relay uses the respective default logic state shown above. 2-12 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 27: Select Combinations Of Relay Elements For Tripping And Other Purposes

    Figure 2.6: SEL-251 Relay SEL Control Equations Block Diagram OGIC Select Combinations of Relay Elements for Tripping and Other Purposes The 48-bit Relay Word contains relay elements, intermediate logic results, and programmable logic variables. Date Code 20000421 Specifications 2-13 SEL-251, -2, -3 Instruction Manual...

  • Page 28: Table 2.2: Sel-251 Relay Word

    Table 2.2: SEL-251 Relay Word 51QP 51NP 50NL 50NH 50LT 51QT 50QT 51NT 50NLT 79RS 79CY 79LO 79SH 52AT 52BT PDEM QDEM NDEM TCMA TRIP ! indicates NOT Phase time-overcurrent element pickup Phase definite-time overcurrent element pickup Phase instantaneous overcurrent element...

  • Page 29: Time Delayed Variables St, Kt, And Zt

    TK and TZ, respectively. TS and TK are driven by any OR-combination of Relay Word elements in R1...R3 and R1...R4, respectively. Any AND-combination of Relay Word elements A through !L may drive timer TZ. Figure 2.7: Relay Word Bit Realizations Date Code 20000421 Specifications 2-15 SEL-251, -2, -3 Instruction Manual...

  • Page 30: Use !L For Inversion

    Use the SHOWSET command to print all relay settings including the SEL Control Equa- OGIC tions configuration. You can inspect settings in the sample event report in Section 4: Event Reporting. 2-16 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 31: Sel Ogic Control Equations Settings In Each Setting Group

    The last two indicators (RS, LO) show the state of the reclosing relay (reset or lockout). Figure 2.9: SEL-251 Relay Front Panel Target LEDs The FAULT TYPE LEDs latch and remain lit until the TRIP output deasserts and one of the following occurs: •...

  • Page 32: Reclose Cancel Conditions

    An input assigned to RE (reclose enable) is not asserted, An input assigned to DT (direct trip) is asserted, The CF (close fail) condition occurs, or The OPEN command is enabled and executed. 2-18 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 33: Sequence Coordination

    If the circuit breaker is closed and the TRIP output contacts are not asserted, SEQ(1) increments the reclosing relay shot counter every time SEQ(1) goes from the state SEQ(1) = 1 to SEQ(1) = 0. Date Code 20000421 Specifications 2-19 SEL-251, -2, -3 Instruction Manual...

  • Page 34: Selectable Setting Groups

    The SEL-251 Relay is reset (79RS = 1, shot = 0) and has four open intervals set (four shots to lockout). In the example, a permanent ground fault greater than 50NL in magnitude occurs beyond the line recloser. Because 50NLT and the line recloser fast curve are properly coordinated, the line re- closer operates twice on its fast curve and the SEL-251 Relay doesn't trip.

  • Page 35: Table 2.3: Setting Group Selection Input Truth Table

    If PDEM, QDEM, and NDEM are assigned to programmable output contacts (A1 - A4), a false alarm would result. To overcome this problem, set DEMR = Y. With this setting, the relay resets demand values to zero when the active setting group changes. Date Code 20000421 Specifications 2-21 SEL-251, -2, -3 Instruction Manual...

  • Page 36: Circuit Breaker Monitor

    REAKER ONITOR The SEL-251 Relay detects every circuit breaker trip operation. It designates each trip as one caused by the relay or an external device and maintains a running count of each. The relay also maintains a running sum of the interrupted current in each circuit breaker pole for relay and external trips.

  • Page 37: Self-Tests

    The relay checks random-access memory (RAM) to ensure that each byte can be written to and read from. There is no warning state for this test. If the relay detects a problem, it transmits a Date Code 20000421 Specifications 2-23 SEL-251, -2, -3 Instruction Manual...

  • Page 38: Read-Only Memory

    It transmits the STATUS message to indicate a failed test. The ALARM relay remains closed after a setting failure. Table 2.5 shows relay actions for any self-test condition: warning (W) or failure (F). 2-24 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 39: Irig-B Input Description

    CAL digital filter method. The CAL filter eliminates dc offset and reduces the decaying exponential offset that may be present on the input signal fol- lowing a fault. Date Code 20000421 Specifications 2-25 SEL-251, -2, -3 Instruction Manual...

  • Page 40: Torque Control

    If neither TCP or !TCP is assigned to an input, the phase and negative-sequence overcurrent elements selected in the ETC(1) setting are not externally torque controlled. The selected phase and negative-sequence overcurrent elements are always enabled with respect to external torque control. 2-26 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 41: Internal Torque Control

    Figure 2.11. When one high-side fuse blows, unbalanced voltages are applied to the transformer bank and its connected load. The SEL-251 Relay includes logic that detects high-fuse operations by measuring the low-side voltages. The logic also rejects operations of low-side Voltage Transformer (VT) fuses.

  • Page 42: What Happens When A High-Side Fuse Blows

    0.58 per unit. With these facts in mind, the logic described below is easy to understand. How Does the SEL-251 Relay Detect Transformer Fuse Operations? When the relay setting 27C = 4, the 27 phase-to-phase undervoltage logic detects high-side fuse operations.

  • Page 43: Use The Detection Logic To Trip Or Indicate

    0.72 per unit threshold and the 27 equation is not satisfied. Use the Detection Logic to Trip or Indicate Since certain faults may also present these voltages to the SEL-251 Relay, you may wish to use a nondedicated SEL...

  • Page 44: Fault Locator

    (4:1 or more), fault type becomes immediately apparent as single- or two-phase. If not, the same current is load compensated by the two corresponding prefault current rows in the first cycle of the event report. 2-30 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 45: Nomographs

    The relay fault locator is designed for circuits having a constant per-unit length impedance. This is often the case with transmission lines. However, distribution lines often have conductor changes, resulting in different per-unit length impedances. Nomographs are used to compensate Date Code 20000421 Specifications 2-31 SEL-251, -2, -3 Instruction Manual...

  • Page 46: Event Report

    • Any TRIP output • Assertion of an input assigned to the ET function • TRIGGER command execution See Section 4: Event Reporting for more information on event reports. 2-32 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 47 ë ê û ú 0 246 0 240 Curve 4: Extremely Inverse - see Figure 2.17 é ù 5 67 0 0352 ë ê û ú 0 194 0 192 Date Code 20000421 Specifications 2-33 SEL-251, -2, -3 Instruction Manual...

  • Page 48: Figure 2.14: Moderately Inverse Curves

    Figure 2.14: Moderately Inverse Curves Figure 2.15: Inverse Curves Figure 2.16: Very Inverse Curves Figure 2.17: Extremely Inverse Curves 2-34 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 49: Figure 2.18: Sel-251 Phase Overcurrent Logic Diagrams

    Figure 2.18: SEL-251 Phase Overcurrent Logic Diagrams Date Code 20000421 Specifications 2-35 SEL-251, -2, -3 Instruction Manual...

  • Page 50: Figure 2.19: Sel-251 Negative-Sequence Overcurrent Logic Diagrams

    Figure 2.19: SEL-251 Negative-Sequence Overcurrent Logic Diagrams 2-36 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 51: Figure 2.20: Sel-251 Ground/Residual Overcurrent Logic Diagrams

    Figure 2.20: SEL-251 Ground/Residual Overcurrent Logic Diagrams Date Code 20000421 Specifications 2-37 SEL-251, -2, -3 Instruction Manual...

  • Page 52: Figure 2.21: Sel-251 Overcurrent And Undervoltage Elements

    Figure 2.21: SEL-251 Overcurrent and Undervoltage Elements 2-38 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 53: Figure 2.22: Sel-251 Transformer Blown-Fuse Detection Logic

    Figure 2.22: SEL-251 Transformer Blown-Fuse Detection Logic Date Code 20000421 Specifications 2-39 SEL-251, -2, -3 Instruction Manual...

  • Page 54: Figure 2.23: Sel-251 Demand Ammeters

    Figure 2.23: SEL-251 Demand Ammeters 2-40 Specifications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 55: Figure 2.24: Sel-251 Programmable Trip Logic Diagram

    Figure 2.24: SEL-251 Programmable Trip Logic Diagram Figure 2.25: SEL-251 Close Logic Diagram Date Code 20000421 Specifications 2-41 SEL-251, -2, -3 Instruction Manual...
  • Page 57 COPY m n........................3-19 GROUP n........................3-20 OPEN.......................... 3-20 PASSWORD (1 or 2) password ................. 3-21 SET n p ........................3-21 SET G p ........................3-27 SEL-251 Relay Command Summary ..................3-31 Date Code 970103 Table of Contents SEL-251, -2, -3 Instruction Manual...
  • Page 58 TABLES Table 3.1: SEL-251 Conventional Terminal Block Model Relay Serial Port Connector Pin Assignments........................3-2 Table 3.2: SEL-251 Plug-In Connector Model Relay Serial Port Connector Pin Assignments ..... 3-3 Table 3.3: Target LED Assignments...................... 3-17 FIGURES Figure 3.1: 9-Pin Connector Pin Number Convention ................3-2...

  • Page 59: Section 3: Communications

    Caution: Do not select two baud rates for the same port as this can damage the relay baud rate generator. The relay is shipped with Port 1 set to 300 baud and Port 2F/2R set to 2400 baud. Date Code 970103 Communications SEL-251, -2, -3 Instruction Manual...
  • Page 60 Figure 3.1: 9-Pin Connector Pin Number Convention Table 3.1 and Table 3.2 list port pin assignments and signal definitions for the conventional terminal block model and the plug-in connector model, respectively. Table 3.1: SEL-251 Conventional Terminal Block Model Relay Serial Port Connector Pin Assignments Port 1,...

  • Page 61: Communications Protocol

    Table 3.2: SEL-251 Plug-In Connector Model Relay Serial Port Connector Pin Assignments Port 1, Port 2R Port 2F Description +5 Vdc +5 Vdc available if JMP12 installed Receive data input. Transmit data output. +IRIG-B +IRIG-B available if JMP14 installed -IRIG-B -IRIG-B available if JMP13 installed The relay asserts this line under normal conditions.

  • Page 62: Command Characteristics

    When the power is first turned on, the relay is in Access Level 0 and honors only the ACCESS command. It responds "Invalid command" or "Invalid access level" to any other entry. Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 63: Startup

    Enter the password TAIL when prompted. After you enter the second password, the relay opens access to Level 2, as indicated by the following message and Level 2 prompt (=>>): Date Code 970103 Communications SEL-251, -2, -3 Instruction Manual...

  • Page 64: Command Descriptions

    The following display indicates successful access: =ACCESS <ENTER> ACCESS <ENTER> Password: OTTER <ENTER> OTTER <ENTER> Example 21.6 kV distribution feeder Date: 04/01/93 Time: 14:03:57 Level 1 => The => prompt indicates Access Level 1. Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 65: Access Level 1 Commands

    If circuit breaker auxiliary contact operation lags too far behind circuit breaker main contact operation, current may already be interrupted when the circuit breaker auxiliary contact changes status. Thus, no interrupted current would be measured. Date Code 970103 Communications SEL-251, -2, -3 Instruction Manual...

  • Page 66: Breaker R

    The relay sets the date, pulses the ALARM relay closed as it stores the year in EEPROM (if the year input differs from the year stored), and displays the new date. Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 67: Event N

    GROUP TARGETS 1 4/2/91 01:36:59.070 AG T 2.43 2798 INSTAQN 2 3/17/91 08:07:40.129 CG T 3.52 2361 INSTCQN 3 3/17/91 08:07:35.133 CG T 3.51 2364 INSTCQN 4 3/15/91 01:07:35.862 TRIG => Date Code 970103 Communications SEL-251, -2, -3 Instruction Manual...
  • Page 68 EVENT column. These conditions are: : programmable TRipping variable : Direct Trip input OPEN : OPEN command : programmable Event Report trigger variable : External Trigger input TRIG : TRIGGER command 3-10 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 69: Irig

    "IRIGB DATA ERROR." Note: Normally, it is not necessary to synchronize using this command because the relay automatically synchronizes every few minutes. The command is provided to speed testing. Date Code 970103 Communications 3-11 SEL-251, -2, -3 Instruction Manual...

  • Page 70: Meter N

    The optional parameter n selects the number of times the relay displays meter data. To display a series of eight meter readings, type METER 8 <ENTER>. 3-12 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 71: Meter D

    C=414 R=15 3I2=13 P=14.701 Q=1.280 => The demand values automatically reset if an active setting group change is made with global setting DEMR=Y (see SET G p in this section). Date Code 970103 Communications 3-13 SEL-251, -2, -3 Instruction Manual...

  • Page 72: Meter Rp

    The display also includes the global settings (settings common to all groups). The SHOWSET output pauses twice, as shown in the following example. Press <ENTER> to continue viewing the next section of settings. 3-14 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 73 DEMR =Y CFT =60 TDUR =4 TFT =30 TGR =180 ITT =5 TIME1=15 TIME2=0 AUTO =2 RINGS=3 IN1 =SS1 IN2 =DT IN3 =RE IN4 = IN5 =52A IN6 = => Date Code 970103 Communications 3-15 SEL-251, -2, -3 Instruction Manual...

  • Page 74: Status

    When relay power is first turned on, the LED display indicates the functions marked on the front panel. Using the TARGET command, you may select any one of the following nine sets of data to display on the LEDs. 3-16 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 75 If you place the relay in service with a target level other than Level 0, it automatically returns to target Level 0 when an automatic message transmits to a timed out port. While this feature Date Code 970103 Communications 3-17 SEL-251, -2, -3 Instruction Manual...

  • Page 76: Target R

    Use TRIGGER to inspect input voltages. For example, when the relay is first installed, execute the TRIGGER command, draw the phasors (Section 4: Event Reporting explains how to do this), and check for the proper polarity and phase sequence of the inputs. 3-18 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 77: Access Level 2 Commands

    COPY command execution clears the event report buffer. If n is the active setting group, the ALARM output contact closes momentarily. =>>COPY 4 6 COPY 4 6 Are you sure (Y/N) ? Y <ENTER> Y <ENTER> Please wait... Settings copied => Date Code 970103 Communications 3-19 SEL-251, -2, -3 Instruction Manual...

  • Page 78: Group N

    To open the power circuit breaker by command, type OPEN <ENTER>. The prompt "Open BREAKER (Y/N) ?" is transmitted. Answering Y <ENTER> yields a second prompt: "Are you sure (Y/N) ?" Answering Y <ENTER> again closes the TRIP output relay as described above. 3-20 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 79: Password (1 Or 2) Password

    SET n allows entry of relay settings and logic for setting group n. At the setting procedure prompts (?), enter new data or press <ENTER> to retain existing settings. You can jump to a Date Code 970103 Communications 3-21 SEL-251, -2, -3 Instruction Manual...
  • Page 80 Answer Y <ENTER> to approve the new settings; the relay enables them and clears the event buffer. If the active group is the same as the one you are setting, the ALARM output pulses closed. 3-22 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 81 QDEM : 3I2 Dem Thr, A sec ........= 12.00 0.25-12.00 Negative-sequence demand ammeter threshold for QDEM NDEM : IR Dem Thr, A sec........= 1.00 " Ground/residual demand ammeter threshold for NDEM Date Code 970103 Communications 3-23 SEL-251, -2, -3 Instruction Manual...
  • Page 82 51QTD : Time Dial...........= 15.00 0.50-15.00 Time dial for negative-sequence time-overcurrent element 51QT 51QC : Curve 1,2,3 or 4 .........= 3 Curve for negative-sequence time-overcurrent element 51QT 1=moderately inverse, 2=inverse, 3=very inverse, 4=extremely inverse 3-24 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 83 1=moderately inverse, 2=inverse, 3=very inverse, 4=extremely inverse 51RS : Dly Reset Y/N?..........= N Time delay reset for phase time-overcurrent element 51NT? (If N, 51T resets 1 cycle after 51P drops out) Date Code 970103 Communications 3-25 SEL-251, -2, -3 Instruction Manual...
  • Page 84 Input into timer TK (TK output is Relay Word bit KT) L(1234) Input into an inverter (output is Relay Word bit !L) A1(1234) = TF ? A1 output contact setting A2(1234) = NDEM ? A2 output contact setting 3-26 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 85: Set G P

    The relay displays the new global settings and the active group settings. Answer Y <ENTER> to enable the new global settings. The relay will pulse the ALARM output as the new global settings are stored in memory. Date Code 970103 Communications 3-27 SEL-251, -2, -3 Instruction Manual...
  • Page 86 Setting Group Selection Input 2 (assign to IN2 only) Setting Group Selection Input 3 (assign to IN3 only) External Torque Control (Phase and Negative-Sequence Elements) !TCP (inverted sense of TCP) 3-28 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 87 Also, if 52AR or !52AR is assigned to an input, the circuit breaker status function is time delayed by 10 cycles to qualify circuit breaker opening. This is done for certain application needs (see System Restoration After Underfrequency Load- Date Code 970103 Communications 3-29 SEL-251, -2, -3 Instruction Manual...
  • Page 88 Enter zero as the timeout setting of the appropriate port if automatic transmissions will be monitored by a dedicated channel or printed on a dedicated printer. 3-30 Communications Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 89: Relay Command Summary

    SEL-251, -2, -3 RELAY COMMAND SUMMARY Access Level 0 ACCESS Answer password prompt (if password protection is enabled) to enter Access Level 1. Third unsuccessful attempt pulses ALARM contacts closed for one second. Access Level 1 2ACCESS Answer password prompt (if password protection is enabled) to enter Access Level 2. This command always pulses the ALARM contacts closed for one second.
  • Page 90 TDUR, bypassing all settings before TDUR). If optional p is not used, the setting procedure starts at the beginning. The SET G command pulses ALARM contacts closed and clears event buffers when new settings are stored. Command Summary Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 91 Externally Triggered Event Report ..................4-5 Fault Triggered Event Report....................4-6 Example Event Report 1....................... 4-7 Example Event Report 2....................... 4-8 Firmware Identification......................4-10 TABLES Table 4.1: Event Report Triggering Actions ..................4-1 Date Code 970103 Table of Contents SEL-251, -2, -3 Instruction Manual...

  • Page 93: Section 4: Event Reporting

    Due to the length of the full report, it is not automatically transmitted. You can display the full report with the EVENT command. Date Code 970103 Event Reporting SEL-251, -2, -3 Instruction Manual...

  • Page 94: Long Event Report

    The relay determines voltage and current data in the event report using the following steps. The process uses secondary quantities presented to the rear panel of the relay. 1. Two-pole, low pass filters with cutoff frequencies of approximately 85 Hz filter input analog signals. Event Reporting Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 95: Relay Element, Output Contact, And Input Data

    Relay elements, inputs, and output contact states appear in the right-hand columns of the event report. The following information lists symbols corresponding to asserted combinations of elements ("1" indicates element/output contact assertion or input energization). Date Code 970103 Event Reporting SEL-251, -2, -3 Instruction Manual...
  • Page 96 (not possible) (not possible) 51QP 51QT Circuit breaker alarms TCMA 50QT (not possible) Ground\residual overcurrent Output contacts 51NP 51NT T&C TRIP CLOSE (not possible) 50NL 50NLT 1&2 (not possible) B (Both) Event Reporting Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 97: Example Event Reports

    In addition, note that load is flowing out to the feeder as indicated by each phase current lagging the respective phase voltage by the load flow angle. Date Code 970103 Event Reporting SEL-251, -2, -3 Instruction Manual...

  • Page 98: Fault Triggered Event Report

    2 cycles later (setting 50NLT = 2). 50NLT is set to initiate tripping via the programmable tripping variable TR(1246). Comments to the right of the event report and settings explain additional details. Event Reporting Date Code 970103 SEL-251, -2, -3 Instruction Manual...

  • Page 99: Example Event Report 1

    7505 ..R..13B -262 1520 -11479 9959 ..R..13B Event : TRIG Location Shot: 0 Targets: Event Summary Currents: (ABCQN; amps, primary) Date Code 970103 Event Reporting SEL-251, -2, -3 Instruction Manual...

  • Page 100: Example Event Report 2

    -7865 ..C. ..3. 136 -11649 1972 9679 ..C. ..3. 136 Event : AG T Location: 2.43 Shot: 0 Targets: INSTAQN Event Summary Currents (A pri), ABCQN 2798 2741 2742 Event Reporting Date Code 970103 SEL-251, -2, -3 Instruction Manual...
  • Page 101 TIME1=15 TIME2=0 AUTO =2 RINGS=3 IN1 =SS1 IN2 =DT IN3 =RE IN4 = Input IN6 is used as a permissive trip IN5 =52A IN6 = input in the above logic Date Code 970103 Event Reporting SEL-251, -2, -3 Instruction Manual...

  • Page 102: Firmware Identification

    IRMWARE DENTIFICATION The SEL-251 Relay provides a means of interpreting Firmware Identification Data (FID). The FID string is included near the top of each long event report. The string format is as follows: FID = [PN] - R[RN] - V[VS] - D[RD] - E[ER], Where: [PN] = Product Name (e.g., SEL-251)
  • Page 103 Bus-Tie Relay Setting Changes....................5-22 Clock-Driven Setting Group Selection..................5-22 Demand-Driven Setting Group Selection................... 5-22 System Restoration After Underfrequency Load Shedding............5-23 Settings Sheets..........................5-25 TABLES Table 5.1: System Conditions and Currents Generated ................. 5-12 Date Code 20000421 Applications SEL-251, -2, -3 Instruction Manual...
  • Page 104 Figure 5.13: Distribution Feeder Relay Backup Scheme ............... 5-21 Figure 5.14: Main/Auxiliary Bus with Bus-Tie Circuit Breaker ............5-22 Figure 5.15: Underfrequency Load Shedding and Reclose Initiate Supervision ........5-24 Figure 5.16: Timing for Reclose Initiation..................... 5-24 Table of Contents Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 105: Section 5: Applications

    SECTION 5: APPLICATIONS This section is included as a tool for applying the SEL-251 Relay. The information does not represent suggested settings or standards. Please refer to Section 2: Specifications and Section 3: Communications and be sure the settings you choose result in relay performance appropriate to your application.

  • Page 106: Fuse-Saving Scheme Using The 79Sh Bit

    OGIC B(12) = 50NL E(34) = 79SH V(56) = B*E TR(1246) = V+... (TR is the programmable trip condition) effectively, TR(1246) = 50NL*79SH+... close TRIP output contacts = TR + ... Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 107: Fuse-Saving Scheme Using The 52At Bit

    Figure 5.1 (ground fault 3I current > 50NL), the 50NL element trips the feeder circuit breaker. The circuit breaker opens. The reclosing relay closes the circuit breaker after the first open interval time expires. Date Code 20000421 Applications SEL-251, -2, -3 Instruction Manual...

  • Page 108: Trip-Saving Scheme

    AVING CHEME Trip saving is the opposite of fuse saving. In a trip-saving scheme, the SEL-251 Relay definite- time overcurrent elements have total coordination with tap fuses near the substation. No attempt is made to save the fuse in a fault situation. For a fault to the load side of a tap fuse, the fuse will clear the fault and the SEL-251 Relay will not operate at all.

  • Page 109: Blocking Schemes For Cold Load Inrush

    Electric System, Lincoln, Nebraska, Transmission & Distribution, May 1990, pp. 72-76. In these papers, trip-saving implementations required extra timers for the instantaneous relays to realize definite-time overcurrent elements. Definite-time overcurrent elements are already available in the SEL-251 Relay, eliminating the need for external timers. LOCKING CHEMES FOR...
  • Page 110 To disable 50L only after the circuit breaker closes from the lockout state, make the following settings. Using SEL Control Equations: OGIC S(123) = 50C B(12) = 50L E(34) = 79RS+79CY+ST V(56) = B*E TR(1246) = V+... (TR is the programmable trip condition) Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 111: Blocking Scheme For Cold Load Inrush Using The 52At Bit

    52AT drops out when 52ADO time expires after the recloser goes to lockout (the circuit breaker is open and 52A = 0). This may be desirable since open interval times are not long Date Code 20000421 Applications SEL-251, -2, -3 Instruction Manual...

  • Page 112: Disable Ground/Residual Overcurrent Elements

    Ground/residual overcurrent elements in the SEL-251 Relay can be disabled by inputs functioning as permissive trip, block trip, or torque control inputs. You can apply the principles in the following examples to other elements.

  • Page 113: Disable Ground/Residual Overcurrent Elements With Block Trip Input

    = 52AT L(1234) = IN5 (input IN5 will function as a block trip input) V(56) = A*!L (!L=NOT(L) = NOT(IN5)) W(56) = B*E*!L TR(1246) = V+W+... (TR is the programmable trip condition) Date Code 20000421 Applications SEL-251, -2, -3 Instruction Manual...

  • Page 114: Disable Ground/Residual Overcurrent Elements With Torque Control Input

    Implementation of this scheme using the external torque control function is much more efficient than the previous two examples. You can use the SEL Control Equations variables saved to OGIC implement other schemes as needed. 5-10 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 115: Minimum Response Time For Time-Overcurrent Elements

    TRIP output contacts = TR + ... Figure 5.7: Minimum Response Time Using Ground/Residual Elements EGATIVE EQUENCE LEMENTS ROTECT FOR HASE AULTS Table 5.1 shows different system conditions and the currents generated by each. Date Code 20000421 Applications 5-11 SEL-251, -2, -3 Instruction Manual...
  • Page 116 LL faults and three-phase faults. Phase overcurrent relays are sensitive to load current; their pickup settings must exceed load current levels. Negative-sequence overcurrent relay elements in the SEL-251 Relay respond to 3xI current. These elements can be set to cover LL faults more sensitively than phase overcurrent elements.

  • Page 117: Negative-Sequence Overcurrent Elements And Delta-Wye Transformers

    (secondary amps) 50QT time delay The SEL-251 Relay phase and ground overcurrent elements have similar element types and settings. If you coordinate the negative-sequence time-overcurrent element (51QT) with the phase time- overcurrent element of a line recloser, settings can be as sensitive as the line recloser phase time- overcurrent element pickup for LL faults.
  • Page 118 Figure 5.8: Phase-To-Ground Fault on Delta-Wye Transformer Secondary 5-14 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 119 Figure 5.9: Phase-To-Phase Fault on Delta-Wye Transformer Secondary Date Code 20000421 Applications 5-15 SEL-251, -2, -3 Instruction Manual...

  • Page 120: Summary Of Figure 5.9

    TRIP output contacts = TR + ... Relays on different feeders can have different TKPU time delay pickup settings so certain feeders are tripped before others during a system underfrequency condition. 5-16 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 121: Undervoltage Load Shedding

    Control Equations: OGIC A1(1234)= TF Output contact A1 operates as a breaker failure output. Breaker failure applications need the following setting relationship. TFT (Trip Failure Time) > TDUR (Trip Duration Time) Date Code 20000421 Applications 5-17 SEL-251, -2, -3 Instruction Manual...

  • Page 122: Breaker Failure Implementation Notes

    (underfrequency or undervoltage application) V(56) = KT*!L (!L limits the duration of KT) TR(1246) = V+... (TR is the programmable trip condition) close TRIP output contacts = TR + ... 5-18 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 123: Residual Current Unbalance Alarm

    The 79CY bit asserts when the reclosing relay is in the reclose cycle state. Using SEL Control Equations: OGIC A3(1346)= 79CY (Output contact A3 should be configured as a "b" contact) Date Code 20000421 Applications 5-19 SEL-251, -2, -3 Instruction Manual...

  • Page 124: Extra Alarm Output Contact

    Depending on the nature of the load-tap-changer control circuit, this application may be best implemented by having an the SEL-251 Relay output contact connect to an interposing relay. The interposing relay can then connect to the load-tap-changer control circuit.
  • Page 125 With the SEL-251 Relay ALARM output contact supervising the SEL-251C Relay TRIP, the SEL-251 Relay A4 output contact can function as an extra ALARM output contact by the placement of jumper JMP3 in the alarm position. The A4 output contact is made a "b" contact by soldering wire jumper JMP5 in the B position.

  • Page 126: Feeder Relay Setting Changes

    ELECTION Trigger a change to less sensitive settings when demand (phase, negative-sequence or ground/residual) encroaches on relay settings, thus avoiding nuisance trips. Set an alarm so problems can be investigated. 5-22 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 127: System Restoration After Underfrequency Load Shedding

    After a feeder circuit breaker has been tripped by an underfrequency relay, the reclosing relay in the SEL-251 Relay can reclose the breaker, after system frequency returns to normal. Manual or SCADA closing of the breaker is not necessary. This can be of benefit in remote substations that are not readily accessible by utility personnel or do not have SCADA-type control.
  • Page 128 Figure 5.15: Underfrequency Load Shedding and Reclose Initiate Supervision Figure 5.16: Timing for Reclose Initiation 5-24 Applications Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 129: Settings Sheets

    ETTINGS HEET Page 1 of 5 SEL-251, -2, -3 R OR THE ELAY Date ELAY ETTINGS ROUP General Data Relay Identifier (39 characters) ID = Current Transformer Ratio (0.001-10000) CTR = Potential Transformer Ratio (0.001-10000) PTR = Positive-Sequence Line Resistance, Ohms pri (0.001-10000) R1 = Positive-Sequence Line Reactance, Ohms pri (0.001-10000)
  • Page 130 ETTINGS HEET Page 2 of 5 SEL-251, -2, -3 R OR THE ELAY Date ELAY ETTINGS ROUP Negative-Sequence Definite-Time Overcurrent Element Negative-Sequence Definite-Time Overcurrent Pickup, A sec (0.50-100.00)* 50Q = Negative-Sequence Definite-Time Overcurrent Time Delay, cycles (0- 50QT = 16000) Negative-Sequence Time-Overcurrent Element Negative-Sequence Time Overcurrent Pickup, A sec (1.00-12.00)*...
  • Page 131 ETTINGS HEET Page 3 of 5 SEL-251, -2, -3 R OR THE ELAY Date ELAY ETTINGS ROUP General Purpose Timers Timer TS Time Delay Pickup, cycles (0-16000) TSPU = Timer TS Time Delay Dropout, cycles (0-16000) TSDO = Timer TK Time Delay Pickup, cycles (0-16000)
  • Page 132 ETTINGS HEET Page 4 of 5 SEL-251, -2, -3 R OR THE ELAY Date ELAY ETTINGS ROUP AND Variables (AND combination of Relay Word bits A-!L) OGIC V(56), Relay Word bit V V(56) = W(56), Relay Word bit W W(56) =...
  • Page 133 ETTINGS HEET Page 5 of 5 SEL-251, -2, -3 R OR THE ELAY Date LOBAL ETTINGS General Data Reset the Demand Values with an Active Setting Group Change (Y, N) DEMR = Close Failure Timer, cycles (0-16000) CFT = Trip Duration Timer, cycles (0-63)
  • Page 135 EIA-232 and IRIG-B Installation ..................6-8 EIA-232 Cables......................6-8 IRIG-B Input Description ................... 6-10 Installation Checkout........................6-11 SEL Direction and Polarity Check Form ................... 6-21 TABLES Table 6.1: IRIG-B Pin Definitions ......................6-5 Date Code 20000421 Table of Contents SEL-251, -2, -3 Instruction Manual...
  • Page 136 Figure 6.3: SEL-251 SLP Relay Dimensions and Drill Plan ..............6-14 Figure 6.4: SEL-251 Plug-In Connector Model Relay Horizontal Front and Rear Panel Drawings ..6-15 Figure 6.5: SEL-251 LP Relay Dimensions and Drill Plan (for relays with 1-amp nominal current inputs)......................

  • Page 137: Section 6: Installation

    9 connect directly to frame (chassis) ground. See Table 3.1 for pin assignment. Warning: Do not rely upon pins 5 and 9 for safety grounding, since their current-carrying capacity is less than control-power short circuit current and protection levels. Date Code 20000421 Installation SEL-251, -2, -3 Instruction Manual...

  • Page 138: Jumper Selection

    All the output contacts can be configured as "a" or "b" contacts with soldered wire jumpers JMP4 through JMP11 (each jumper has positions A and B). The output contact/soldered wire jumper correspondence is as follows: Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 139: Communication Port External Power Jumpers

    Figure 6.1. The following cable listings show several types of EIA-232 cables. These and other cables are available from SEL. Cable configuration sheets are also available at no charge for a large number of devices. Contact the factory for more information. Date Code 20000421 Installation SEL-251, -2, -3 Instruction Manual...

  • Page 140: Eia-232 Cables

    (female chassis connector, as viewed from outside panel) Figure 6.1: Nine-Pin Connector Pin Number Convention EIA-232 Cables Cable 234A SEL-251 9-Pin *DTE Device Jumper Cable 222 SEL-251 **DCE Device 20 DTR Cable 231 SEL-PRTU SEL-251 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 141: Irig-B Input Description

    Table 6.1: IRIG-B Pin Definitions Name Description IRIGIN HI Positive IRIG-B input IRIGIN LOW Negative IRIG-B input 5, 9 Ground for ground wires and shields * Consult the factory before using these power supply outputs Date Code 20000421 Installation SEL-251, -2, -3 Instruction Manual...

  • Page 142: Installation: Plug-In Connector Model

    The current connector supplied with the wiring harness is a shorting type connector. When removed from the relay, the connector automatically shorts CT secondaries. The connector can be ordered with #16 - #10 AWG conductors. Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 143: Control Circuits

    9600. To select a baud rate for a particular port, place the jumper so it connects a pin labeled with the desired port to a pin labeled with the desired baud rate. Date Code 20000421 Installation SEL-251, -2, -3 Instruction Manual...

  • Page 144: Password Protection Jumper

    SEL. Cable configuration sheets are also available at no charge for a large number of devices. Contact the factory for more information. EIA-232 Cables Cable 234A SEL-251 9-Pin *DTE Device Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 145 Cable 222 SEL-251 **DCE Device 20 DTR Cable 231 SEL-PRTU SEL-251 Cable 239 Data and IRIG-B SEL-2020 SEL-251 Port 2R / J203 +IRIG +IRIG AUX Input / J201 -IRIG -IRIG Date Code 20000421 Installation SEL-251, -2, -3 Instruction Manual...

  • Page 146: Irig-B Input Description

    The IRIG-B serial data format consists of a one second frame containing 100 pulses and divided into fields. The relay decodes the second, minute, hour, and day fields and sets the internal relay clock accordingly. 6-10 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 147: Installation Checkout

    Front Panel Targets Inputs An LED illuminates when a corresponding input is energized with nominal control voltage. Apply nominal control voltage to each input and make sure the corresponding LED illumi- Date Code 20000421 Installation 6-11 SEL-251, -2, -3 Instruction Manual...
  • Page 148 When local checkout is complete, check communications with the instrument via a remote interface (if used). Make sure the automatic port is properly assigned and that desired timeout intervals are selected for each port. Also, be sure to record password settings. 6-12 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 149 Figure 6.2: SEL-251 Conventional Terminal Block Model Relay Horizontal Front and Rear Panel Drawings Date Code 20000421 Installation 6-13 SEL-251, -2, -3 Instruction Manual...
  • Page 150 Figure 6.3: SEL-251 SLP Relay Dimensions and Drill Plan 6-14 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 151 Figure 6.4: SEL-251 Plug-In Connector Model Relay Horizontal Front and Rear Panel Drawings Date Code 20000421 Installation 6-15 SEL-251, -2, -3 Instruction Manual...
  • Page 152 Figure 6.5: SEL-251 LP Relay Dimensions and Drill Plan (for relays with 1-amp nominal current inputs) 6-16 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 153 Figure 6.6: Panel Cutout Diagram for Panel-Mount Relays Figure 6.7: SEL-251 Conventional Terminal Block Model DC External Connection Diagram (Typical) Date Code 20000421 Installation 6-17 SEL-251, -2, -3 Instruction Manual...
  • Page 154 Figure 6.8: SEL-251 Polarity Sensitive Plug-In Connector Model DC External Connection Diagram (Typical) Figure 6.9: Communications and Clock Connections - One Unit at One Location 6-18 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 155 Figure 6.10: Remote Communications, Local Display, and Clock Connections - Multiple Relay Units at One Location Figure 6.11: SEL Relay Communications Diagram for Connection to the SEL-DTA Date Code 20000421 Installation 6-19 SEL-251, -2, -3 Instruction Manual...
  • Page 156 Figure 6.12: SEL-251 Relay Typical AC External Current and Voltage Connections 6-20 Installation Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 157: Sel Direction And Polarity Check Form

    SEL D IRECTION AND OLARITY HECK DATE: TESTED BY: STATION: SWITCH NO.: EQUIPMENT: INSTALLATION: ROUTINE: OTHER: LOAD CONDITIONS STATION READINGS: MW (OUT)(IN) MVAR (OUT)(IN) VOLTS AMPS MW (+)(-) SEL READINGS: MVAR (+)(-) AS SEEN ON SCREEN I( ) I( ) I( ) V( ) V( )
  • Page 159 SEL D IRECTION AND OLARITY HECK DATE: TESTED BY: STATION: SWITCH NO.: EQUIPMENT: INSTALLATION: ROUTINE: OTHER: LOAD CONDITIONS STATION READINGS: MW (OUT)(IN) MVAR (OUT)(IN) VOLTS AMPS MW (+)(-) SEL READINGS: MVAR (+)(-) AS SEEN ON SCREEN I( ) I( ) I( ) V( ) V( )
  • Page 161 Factory Assistance........................7-33 TABLES Table 7.1: Fault Locator Test Values..................... 7-10 Table 7.2: Current Quantities for 51NT Timing Test Example ............. 7-16 Table 7.3: Contact Inputs and Terminal Numbers ................. 7-28 Date Code 20000421 Table of Contents SEL-251, -2, -3 Instruction Manual...
  • Page 162 Figure 7.2: Communication Interface Setup .................... 7-5 Figure 7.3: Three-Phase Voltage and Current Source Test Connections..........7-8 Figure 7.4: METER Test Connections....................7-12 Figure 7.5: Nine-Pin Connector Pin Number Convention ..............7-29 Table of Contents Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 163: Section 7: Maintenance And Testing

    TDPU timer setting. Simply subtract the latest event report time tag from the previous event report time tag. Section 2: Specifications has further details concerning event report generation. Date Code 20000421 Maintenance and Testing SEL-251, -2, -3 Instruction Manual...

  • Page 164: Low-Level Test Interface

    Low-Level Test Interface The SLP chassis SEL-251 Relay has low-level test interface between the calibrated input module and the separately-calibrated processing module. You may test the relay in either of two ways: conventionally, by applying ac current signals to the relay inputs; or by applying low magnitude ac voltage signals to the low-level test interface.
  • Page 165 The following logic depends on the state of the circuit breaker status input: • Reclosing Relay Logic • Close Function Logic • Trip Circuit Monitor Logic • 52AT and 52BT Functions • Circuit Breaker Monitor Logic Date Code 20000421 Maintenance and Testing SEL-251, -2, -3 Instruction Manual...

  • Page 166: Initial Checkout

    We recommend testing the SEL-251 Relay with a latching relay to simulate line breaker auxiliary contact action. This ensures proper assertion and deassertion of the circuit breaker status function assigned to an input on the back panel. NITIAL HECKOUT The initial checkout procedure should familiarize you with the relay and ensure that all functions are operational.
  • Page 167 In the final installation, we recommend that the relay receive control power from the station dc battery to avoid losing events stored in volatile memory if station service is lost. Date Code 20000421 Maintenance and Testing SEL-251, -2, -3 Instruction Manual...
  • Page 168 Type STATUS and press <ENTER>. The following display should appear on the terminal: Example 21.6 kV distribution feeder Date: 04/01/93 Time: 01:04:56 SELF-TESTS W=Warn F=Fail 5.08 14.92 -14.99 => Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 169 A1(1234)=TF A2(1234)=NDEM PRESS RETURN ? <ENTER> <ENTER> V(56) =B*E*F W(56) =C*E*F X(56) Y(56) Z(56) A3(1346)=79CY A4(2346)= TR(1246)=50H+51T+51NT+V RC(1246)=50H+TF ER(1246)=TF+W SEQ(1) = ETC(1) = ITC(1) = Continued on next page Date Code 20000421 Maintenance and Testing SEL-251, -2, -3 Instruction Manual...
  • Page 170 Set the B-phase current source to 2 amperes, at the same angle as the B- phase voltage. Set the C-phase current source to 2 amperes, at the same angle as the C-phase voltage. Figure 7.3: Three-Phase Voltage and Current Source Test Connections Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 171 Z1 = 0.25 + j2.50 W and Z0 = 0.05 + j0 = 53 W (21.6 kV). Use the following settings: CTR = 120 PTR = 180 R1 = 0.58 X1 = 1.50 Date Code 20000421 Maintenance and Testing SEL-251, -2, -3 Instruction Manual...

  • Page 172: Full Functional Test

    4. Source of synchronized three-phase voltages and at least two currents 5. Ohmmeter or contact opening/closing sensing device 6. Timer with contact inputs for start and stop 7. Plug-in mating connectors/wiring harness (Plug-In Connector model only) 7-10 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 173: What Should Be Tested

    1. Parallel all voltage inputs by connecting terminals 37, 38, and 39 with a jumper. See Figure 7.4 for the test connections. 2. Series all current inputs as shown in Figure 7.4. Date Code 20000421 Maintenance and Testing 7-11 SEL-251, -2, -3 Instruction Manual...
  • Page 174 Difference currents IAB, IBC, and ICA should be less than 12 amperes. The power reading, P (MW) should read: (VA(IA) + (VB)(IB) + (VC)(IC) = 16.20 MW. The reactive power reading Q (MVAR) should be less than 0.3 MVAR. 7-12 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 175: Overcurrent Element Pickup Tests

    You can also test the following element in Relay Word row R2 using the above method (bypass step 2 because 50C cannot be torque controlled). 50C Phase instantaneous overcurrent element (50C overrides internal torque control element 27) Date Code 20000421 Maintenance and Testing 7-13 SEL-251, -2, -3 Instruction Manual...

  • Page 176: Definite-Time Overcurrent Element Timing Tests

    Ð- °+ Ð ° Ð ° The negative-sequence and ground/residual overcurrent elements respond to and 3xI currents, respectively. Thus, for this test all overcurrent elements see 6 A. 7-14 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 177: Time-Overcurrent Element Timing Tests

    For example, if the relay measures 3.45 amperes of residual current, the 51NT bit in the Relay Word asserts 2.33 seconds after 51NP assertion (51NP = 1.15 A; 3x1.15 = 3.45). Table 7.2 shows current quantities for the previous example. Date Code 20000421 Maintenance and Testing 7-15 SEL-251, -2, -3 Instruction Manual...

  • Page 178: Demand Ammeter Timing Tests

    Verify the operating time of the following demand ammeter thresholds. PDEM Phase demand current threshold exceeded QDEM Negative-sequence demand current threshold exceeded NDEM Residual demand current threshold exceeded 7-16 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 179: Reclosing Relay Tests Setup

    Note: These tests should be performed using a circuit breaker simulator to simulate the action of the circuit breaker auxiliary contacts. A simple latching relay works well as a circuit breaker simulator. Date Code 20000421 Maintenance and Testing 7-17 SEL-251, -2, -3 Instruction Manual...
  • Page 180 Connect the SEL-251 Relay TRIP and CLOSE output contacts to the circuit breaker simulator to trip and close the simulator. Connect the simulator output to a relay input assigned to the circuit breaker status function (IN5 = 52A in the following example).

  • Page 181: Reclosing Relay Reset Interval Timer Test

    5. Execute the CLOSE Command or energize the IN4 input (IN4 = DC; direct close) to cause CLOSE output contact assertion. When the circuit breaker simulator output asserts (IN5 = 52A energized), the external and reset interval Date Code 20000421 Maintenance and Testing 7-19 SEL-251, -2, -3 Instruction Manual...

  • Page 182: Reclosing Relay Open Interval Timer Test

    CLOSE output contact asserts. CLOSE output contact assertion indicates that the open interval timer has expired on a particular open interval time period and the relay subsequently asserted the CLOSE output contact. 7-20 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 183: Reclosing Relay States Test

    The front panel LO (lockout) LED illuminates, the A3 output contact asserts (A3 = 79LO), and the A2 output contact deasserts (A2 = 79CY). Date Code 20000421 Maintenance and Testing 7-21 SEL-251, -2, -3 Instruction Manual...

  • Page 184: Reclosing Relay Shot Bit Test

    = 1800 cycles), so the reclosing relay goes to the reset state. The front panel RS (reset) LED illuminates, the A1 output contact asserts (A1 = 79RS), the A2 output contact deasserts (A2 = 79CY), the shot counter 7-22 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 185: Reclosing Relay Sequence Coordination Test

    IN5 is energized (IN5 = 52A) and the front panel RS (reset) LED illuminates after the reset interval timer expires (79RST = 1800 cycles). The A1 output contact asserts (A1 = 79RS) and shot = 0. Date Code 20000421 Maintenance and Testing 7-23 SEL-251, -2, -3 Instruction Manual...
  • Page 186 = 79RS remains asserted). In application, sequence coordination advances the shot counter, keeping the SEL-251 Relay in step with line reclosers (see Multiple Shot Reclosing Relay in Section 2: Specifications). If the reset interval timer expires before current rises above and falls below the 50L level again, the shot counter resets to shot = The number of reclosing shots (automatic reclosures) depends on the number of set open interval times.

  • Page 187: Close Failure Timer Test

    A4(2346) = CF close failure condition 2. Using the SET G command (G signifies the global setting group: settings common to all groups), enter these settings: Date Code 20000421 Maintenance and Testing 7-25 SEL-251, -2, -3 Instruction Manual...

  • Page 188: Trip Failure Timer Test

    1. Using the SET n command (n is the active setting group), program an element (e.g., 50L, phase overcurrent pickup) for tripping via the programmable tripping variable TR: close TRIP output contacts = TR + ... 7-26 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 189 Apply 5 amps of current to one phase of the relay. The TRIP output contacts will immediately assert (5 A > 50L = 4.00 A). The external and trip failure timers start immediately. Date Code 20000421 Maintenance and Testing 7-27 SEL-251, -2, -3 Instruction Manual...

  • Page 190: Input Circuits Test

    -IRIG-B and +IRIG-B, respectively. See Table 3.2 for port pinouts. 3. Execute the IRIG command. Make sure the relay clock displays the correct date and time. 7-28 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 191: Power Supply Voltages Test

    The 12 volt supplies should be within 0.5 volts of their nominal values. ELAY ALIBRATION The SEL-251 Relay is factory calibrated. If you suspect that the relay is out of calibration, please contact the factory. ROUBLESHOOTING Inspection Procedure Complete the following procedure before disturbing the system.

  • Page 192: Troubleshooting Table

    No Prompting Message Issued to Terminal Upon Power-Up 1. Terminal not connected to system. 2. Wrong baud rate. 3. Terminal improperly connected to system. 4. Other port designated AUTO in the relay settings. 7-30 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 193 1. Power supply -15 volt output out of tolerance. See STATUS command in Section 3: Communications. 2. A/D converter failure. Self-Test Failure: Offset 1. Offset drift. Adjust offsets. 2. A/D converter drift. Date Code 20000421 Maintenance and Testing 7-31 SEL-251, -2, -3 Instruction Manual...

  • Page 194: Firmware Upgrade Instructions

    2. Remove the relay front panel by unscrewing the five front panel screws. With the front panel removed, you can see the aluminum drawout assembly. The main board is attached to the top 7-32 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...

  • Page 195: Factory Assistance

    9. If a new serial number label in included with the upgrade, attach the serial number label so the old label is covered. ACTORY SSISTANCE The employee-owners of Schweitzer Engineering Laboratories, Inc. are dedicated to making electric power safer, more reliable, and more economical. Date Code 20000421 Maintenance and Testing...
  • Page 196 We guarantee prompt, courteous, and professional service. We appreciate receiving any comments and suggestions about new products or product improvements that would help us make your job easier. 7-34 Maintenance and Testing Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 197 SETTINGS FOR TESTING DISTANCE RELAYS ........C-1 FIGURES Figure B.1: SEL-251 Conventional Terminal Block Model Main Board Troubleshooting Test Points and Jumper Locations..................B-1 Figure B.2: SEL-251 Plug-In Connector Model Main Board Troubleshooting Test Points and Jumper Locations......................B-2 Date Code 20000421 Table of Contents...
  • Page 199 The firmware versions are listed in chronological order (most recent firmware at top). Firmware Description of Firmware Part/Revision No. SEL-251 Firmware, Revision 4 Main Board Configuration This firmware differs from previous versions as follows: - INST target is now independent of phase targets. SEL-251-3-R552...
  • Page 200 251-3 50 Hz 1 A ABC rotation extended fast meter fast operate This firmware differs from previous versions as follows: - Changed the RINGS setting prompt to "RINGS 1-30". - Added FOP fast operate enable input (applies to SEL-251-3 only). SEL-151-R608...
  • Page 201 Firmware Description of Firmware Part/Revision No. SEL-251 Firmware, Revision 4 Main Board Configuration SEL-151-R604 151 60 Hz 5 A ACB rotation SEL-251-2-R601 ACB rotation extended fast meter SEL-251-2-R404 251-2 60 Hz 5 A extended fast meter SEL-151-R556 151 50 Hz 1 A...
  • Page 202 Firmware Description of Firmware Part/Revision No. SEL-251 Firmware, Revision 4 Main Board Configuration SEL-151-R550 151 50 Hz 1 A SEL-151-R500 151 60 Hz 1 A SEL-151-R451 151 50 Hz 5 A SEL-151-R405 151 60 Hz 5 A SEL-151-R450 151 50 Hz 5 A...
  • Page 203 APPENDIX B - MAIN BOARD TROUBLESHOOTING TEST POINTS AND JUMPER LOCATIONS Figure B.1: SEL-251 Conventional Terminal Block Model Main Board Troubleshooting Test Points and Jumper Locations 5-amp nominal current input main board shown (SLP chassis). The 1-amp main board (LP chassis) has a similar layout, but the test point positions and order are different.
  • Page 204 Figure B.2: SEL-251 Plug-In Connector Model Main Board Troubleshooting Test Points and Jumper Locations Appendix B Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 205 The bottom line of the display offers you a choice of entering new impedance data (I), changing the distance from the source to the bus (B), specifying a new fault location (F), or quitting (Q). Date Code 20000421 Appendix C SEL-251, -2, -3 Instruction Manual...
  • Page 206 GOSUB 1000 4061 VA=0 IB=RR:JB=RI:IC=-IB:JC=-JB 4100 PRINT " VA IC" UA=67:VA=0 4130 PRINT USING"##.# ";UA;UB;UC;IA;IB;IC, AR=I:AI=J:BR=S*R1:BI=S*S1 4132 PRINT FF$ GOSUB 1000 4140 PRINT USING"#### ";VA;VB;VC;JA;JB;JC AR=RR:AI=RI:BR=0:BI=SQR(3) 4150 RETURN GOSUB 1000 Appendix C Date Code 20000421 SEL-251, -2, -3 Instruction Manual...
  • Page 207 SEL-251, -2, -3 RELAY COMMAND SUMMARY Access Level 0 ACCESS Answer password prompt (if password protection is enabled) to enter Access Level 1. Third unsuccessful attempt pulses ALARM contacts closed for one second. Access Level 1 2ACCESS Answer password prompt (if password protection is enabled) to enter Access Level 2. This command always pulses the ALARM contacts closed for one second.
  • Page 208 TDUR, bypassing all settings before TDUR). If optional p is not used, the setting procedure starts at the beginning. The SET G command pulses ALARM contacts closed and clears event buffers when new settings are stored. Command Summary Date Code 970103 SEL-251, -2, -3 Instruction Manual...

This manual is also suitable for:

Sel-251-3Sel-251-2

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