Presentado por: Jesús A. Baez M. ITESM, Departamento de Ingeniería Eléctrica

1. Sistemas Eléctricos Industriales • Coordinación Selectiva de los elementos de protección • Referencia: http://www.bussmann.com • Definiciones • Coordinación con fusibles • Coordinación con interruptores • Ejemplo de coordinación en una planta industrial Presentado por: Jesús A. Baez M. ITESM, Departamento de Ingeniería Eléctrica Monterrey, NL Octubre 2007

2. Definition: The act of isolating a faulted circuit from the remainder of the electrical system, thereby eliminating unnecessary power outages. The faulted circuit is isolated by the selective operation of only the overcurrent protective device closest to the overcurrent condition. Selective Coordination

3. Without Selective CoordinationWith Selective Coordination Selective Coordination: Avoids Blackouts OPENS OPENS NOT AFFECTED NOT AFFECTED UNNECESSARY POWER LOSS Fault Fault

4. Selective Coordination: NEC® 240.2 Definitions Coordination. The proper localization of a fault condition to restrict outages to the equipment affected, accomplished by the choice of selective fault-protective devices.

5. Selective Coordination: Normal Supply Emergency Source Normal Source ATS N E

6. Selective Coordination: Normal Supply Emergency Source Normal Source Unnecessary Feeder Outage ATS N E Opens Not Affected Unnecessary Power Loss Fault X1

7. Selective Coordination: Normal Supply Without Emergency Source Normal Source Unnecessary Main Outage Blackouts Possible! ATS N E Opens Not Affected Unnecessary Power Loss Fault X1

8. Selective Coordination: Normal Supply Without With Emergency Source Emergency Source Normal Source Normal Source Blackouts Possible! ATS ATS N E N E Opens Not Affected Unnecessary Power Loss Fault X1

9. Selective Coordination: Normal Supply Without With Emergency Source Emergency Source Normal Source Normal Source Blackouts Prevented! Blackouts Possible! ATS ATS N E N E Isolated to Branch Only Opens Not Affected Unnecessary Power Loss Fault X1 Fault X1

10. Circuit Breaker Coordination Selective Coordination

11. Coordination - Thermal-Mag Circuit Breakers • Thermal Magnetic Molded Case Circuit Breaker Time-Current Curve • Overload Region • Instantaneous Region • Interrupting Time • Unlatching Time • Interrupting Rating

12. Coordination - Thermal-Mag Circuit Breakers (See SPD) 400A 90A No se tiene selectividad para corrientes de corto circuito en este rango

13. Selective Coordination D C Time B A 4000A Fault Current

14. Lacking Coordination OPENS NOT AFFECTED UNNECESSARY POWER LOSS Fault

15. Selective Coordination - Insulated Case Circuit Breakers (See SPD) • 2000A Insulated Case Circuit Breaker • STD Is an Option - Allows breaker to delay opening • Instantaneous Override built-in: may be as low as 12X the breaker rating • Will often result in lack of coordination

16. Selective Coordination - Insulated Case Circuit Breakers (See SPD) • 2000A Insulated Case with STD and Instantaneous Override and 100A Molded Case Thermal Magnetic Circuit breaker - NO Coordination in Short-Circuit Region (above 21,000A) 2000A 100A

17. Selective Coordination - LV Air Power Circuit Breakers (See SPD) • Short Time Delay - Allows the fault current to flow for up to 30 cycles. • Used to coordinate with downstream • Subjects equipment to high mechanical and thermal stresses, often violating 110.10 • Arc Flash/ Blast Risks Much Higher • High Cost, Larger Equipment

18. Selective Coordination: Fuses

19. Selective Coordination:Fuses (See SPD) Time Current Curves

20. Selective Coordination:Fuses (See SPD) Not Melt Selectivity Ratio Guide Based on Thermal Principle Based on I2t Clear I2t melting > I2t Clearing 1200 A 600 A

21. Selectivity Ratio Table Assures Coordination! No Plotting required! Selective Coordination (See SPD ) Load Side Fuse Line Side Fuse LOW-PEAK® : LOW-PEAK® 2:1 Line:Load Ratio

22. Selective Coordination - Fuses 480V, 3 phase Example: Main: KRP-C 1200 SP Feeder: LPS-RK 200 SP Branch: LPS-RK-30 SP 1200 A GFP MSB 200 A MCC 30 A

23. Use Selectivity Table Main KRP-C 1200 SP Feeder LPS-RK 200 SP Branch LPS-RK 30 SP What happens: Branch Circuit Isca = 5000 A or 50,000A or 300,000A ? Selective Coordination - Fuses

24. Lineside KRP-C 1200SP to Loadside LPS-RK 200SP 1200/200 = 6:1 Table only need 2:1 Selective Coordination Lineside LPS-RK 200SP to Loadside LPS-RK 30SP 200/30= 6.67:1 Table only need 2:1 Selective Coordination Selective Coordination- Fuses

25. Selective Coordination NOT AFFECTED OPENS Fault

26. Are These Selectively Coordinated? Low Peak KRP-C 1000 SP Low Peak LPJ 200 SP Low Peak LPJ 20 SP Fault 10000 Amps

27. Are These Selectively Coordinated? Selectively Coordinated Low Peak KRP-C 1000 SP Low Peak KRP-C 1000 SP Low Peak LPJ 200 SP Low Peak LPJ 200 SP NOT AFFECTED Low Peak LPJ 20 SP Low Peak LPJ 20 SP OPENS Fault 10000 Amps Fault 10000 Amps

28. Are These Selectively Coordinated? 1000 A. CB IT @ 10 X 200 A. CB IT @ 10 X 20 A. CB IT @ 10X Fault 10000 Amps

29. Not Coordinated Are These Selectively Coordinated? 1000 A. CB IT @ 10 X 1000 A. CB IT @ 10 X 200 A. CB IT @ 10 X 200 A. CB IT @ 10 X NOT AFFECTED 20 A. CB IT @ 10X 20 A. CB IT @ 10X OPENS Fault 10000 Amps Fault 10000 Amps

30. OPENS The Issue: Lack of coordination takes out other loads 1000 A. CB IT @ 10 X 200 A. CB IT @ 10 X Unnecessary Blackout 20 A. CB IT @ 10X Fault 10000 Amps

31. Ejemplo de coordinación mostrando protección de los cables