BusCoupler25458747874_Operation_Description.pptx

BUS COUPLER

1. Bus Coupler Operation Description (Beles 400kV Switchyard) Document Ref: 50PO-00214-40 Rev.04 Prepared by Siemens Power Transmission and Distribution Energy Automation

2. 1. Scope This document describes all operator control methods for electrical equipment (HV isolators, circuit breakers) of the Bus Coupler in Beles 400kV Switchyard. It covers manual control commands, interlocks, and auxiliary functions.

3. 2. Definitions – Command Levels Four command levels are defined: Field Level – outdoor control panels (no interlocks, maintenance use) Control Panel Level – via Bay Control Unit (BCU A201) in control room Mimic Panel Level – via switchyard mimic panel (global view) SCADA Level – via remote substation controllers Selection between levels is done using LOC/REM selectors.

4. Command Levels Diagram Simplified schematic illustrating command level hierarchy and selector logic: SCADA → Mimic Panel → Control Panel → Field Level Commands enabled progressively via LOC/REM and K1/K2 selector positions. (Diagram: arrows showing command flow from SCADA down to Field Level)

5. 3. HV Equipment Overview This section details the control, interlocks, and operation consents for Bus Bar isolators, earthing switches, and circuit breaker Q0. Each operation is permitted only if the BCU provides an operation consent based on interlock conditions.

6. Bus Bar A Isolator Q1 – Operation Consents Commands allowed only if: • Isolator motor supply available • CB Q0 open • Related earthing switches open OR interlocks excluded • No CT/CB SF6 faults present Operation possible under: 1. Normal local control (with BCU consent) 2. Local with interlocks excluded (BCU consent bypassed) 3. Mimic Panel / SCADA remote modes

7. Bus Bar B Isolator Q2 – Operation Consents Commands allowed only if: • Isolator motor supply available • CB Q0 open • Related earthing switches open OR interlocks excluded • No CT/CB SF6 faults present Operation possible under: 1. Normal local control (with BCU consent) 2. Local with interlocks excluded (BCU consent bypassed) 3. Mimic Panel / SCADA remote modes

8. Bus Bar A Earthing Switch Q16 – Operation Consents Allowed only if: • Isolator open • Other bays disconnected from bus bar (open or local-interlocks excluded) • Or bay in Local + Bus Bar Interlocks Excluded mode Commands available at Control Panel, Mimic Panel, and SCADA levels.

9. Bus Bar A Earthing Switch Q26 – Operation Consents Allowed only if: • Isolator open • Other bays disconnected from bus bar (open or local-interlocks excluded) • Or bay in Local + Bus Bar Interlocks Excluded mode Commands available at Control Panel, Mimic Panel, and SCADA levels.

10. Bus Bar B Earthing Switch Q17 – Operation Consents Allowed only if: • Isolator open • Other bays disconnected from bus bar (open or local-interlocks excluded) • Or bay in Local + Bus Bar Interlocks Excluded mode Commands available at Control Panel, Mimic Panel, and SCADA levels.

11. Bus Bar B Earthing Switch Q27 – Operation Consents Allowed only if: • Isolator open • Other bays disconnected from bus bar (open or local-interlocks excluded) • Or bay in Local + Bus Bar Interlocks Excluded mode Commands available at Control Panel, Mimic Panel, and SCADA levels.

12. Circuit Breaker Q0 – Overview Manual operations and related interlocks described here. Automatic protection trips and internal faults managed separately via protection relays.

13. Q0 Close Blocking Logic Closing blocked if transient or permanent blocking conditions exist: • Protection trip active • Pole discrepancy trip • Opening or isolator movement in progress • CB springs not charged / SF6 fault • CT SF6 low pressure (if Bay Lockout active) Reset of definitive block only possible locally via BCU display.

14. Q0 Automatic Parallel OFF Allows temporary closing of CB Q0 without synchronism check. Auto-reset when CB closes or timeout expires. Active only in Local Control Mode (manual set via BCU display or SCADA HMI).

15. Q0 Closing and Opening Commands Closing Sequence: • Local/Remote selector = Remote • CB springs charged • No close blocking present • Automatic Parallel OFF or synchronism check satisfied Opening Sequence: • Available from all control levels with proper operation consent.

16. 4. Auxiliary Functions Overview BCU manages several auxiliary functions for safe and automated operation: • Bay lock-out for CT SF6 trip • Isolators auto-opening for CB SF6 trip • Close blocking for protection fault

17. CT SF6 Trip Function In case of CT very low SF6 pressure: • Trips CB Q0 • Inhibits Q0 closing command • Opens and blocks isolators Q1 and Q2 Activated via BCU display (Local) or SCADA HMI (Remote).

18. Isolators Auto-Opening for CB SF6 Trip On CB Q0 SF6 very low-pressure trip: • CB opens automatically • Q1 and Q2 isolators can be configured for auto-opening • Reclosing inhibited until reset Enabled via BCU or SCADA control commands.

19. Close Blocking for Protection Fault When overcurrent protection is faulted, BCU issues 'Bay Not Protected'. Activating this function inhibits Q0 closing command. Operated via BCU display in Local or Interlocks Excluded mode.

20. 5. Protection Tests Steps before relay testing: 1. Set bay to 'Test / Out of Service' mode 2. Disconnect BF start signals (XT terminals 3-4) 3. Apply 87BB protection manual recommendations 4. Disconnect F01 trip outputs (XT terminals 1-2) 5. Use XP01 test socket for current/voltage injection Ensures SCADA alarms and interlocks are bypassed safely.

21. Simplified System Diagram Diagram: Simplified schematic showing interconnection of Q0, Q1, Q2, Q16–Q27, CTs, and Bus Bars A/B. Arrows show control command paths and interlock dependencies managed by BCU.

22. Summary • All HV equipment controlled via hierarchical command structure. • Interlocks and SF6 condition monitoring ensure safety. • Auxiliary and protection functions managed by BCU logic. • Refer to schematic diagrams and logic drawings for full detail. Reference: Siemens Docs 70-VA-0688, 70-VA-0694.