This document outlines typical protection schemes for electrical equipment, including: 1) Radial systems, ring main circuits, and directional comparison protection for distribution feeders. 2) Reverse power monitoring, synchronization, and cable/line protection with dual infeed. 3) Transmission line protection using circuit breakers, reactors, and communication. 4) Transformer and motor protection for small, large, and parallel equipment. 5) Generator protection of various sizes feeding into isolated or earthed networks. 6) Busbar protection using overcurrent relays and impedance-based schemes.

1. ESQUEMAS TIPICOS DE
PROTECCIÓN DE LOS
EQUIPOS ELÉCTRICAS
Ing. Luis Felipe Hernández Zevallos
DLF SAC

2. RADIAL
SYSTEMS

3. RING‐
RING‐MAIN
CIRCUIT

4. SWITCH‐ONTO‐
SWITCH‐ONTO‐FAULT PROTECTION

5. DIRECTIONAL COMPARISON PROTECTION
(CROSS‐
(CROSS‐COUPLING)

6. DISTRIBUTION
FEEDER WITH
RECLOSERS

7. 3‐POLE
MULTISHOT
AUTO‐
AUTO‐
RECLOSURE
(AR,ANSI 79)

8. PARALLEL FEEDER CIRCUIT

9. REVERSE‐
REVERSE‐
POWER
MONITORING
AT DOUBLE
INFEED

10. SYNCHRONIZATION FUNCTION

11. CABLES OR SHORT OVERHEAD LINES
WITH INFEED FROM BOTH ENDS

12. OVERHEAD LINES OR LONGER CABLES
WITH INFEED FROM BOTH ENDS

13. SUBTRANSMISSION LINE

14. TRANSMISSION LINE WITH
REACTOR

15. TRANSMISSION
LINE OR CABLE
(
(WITH WIDE‐
(WITH WIDE‐
BAND
COMMUNICATION)

16. TRANSMISSION
LINE OR CABLE
(
(WITH WIDE‐
(WITH WIDE‐
BAND
COMMUNICATION)

17. TRANSMISSION
LINE,
LINE
BREAKER‐AND‐
BREAKER‐AND‐
A‐HALF
TERMINAL (1)

18. TRANSMISSION
LINE,
LINE
BREAKER‐AND‐
BREAKER‐AND‐
A‐HALF
TERMINAL (2)

19. SMALL
TRANSFORMER
INFEED

20. LARGE OR
IMPORTANT
TRANSFORMER
INFEED

21. DUAL INFEED WITH SINGLE
transformer

22. PARALLEL INCOMING
TRANSFORMER FEEDERS

23. PARALLEL INCOMING TRANSFORMER
FEEDERS WITH BUS TIE

24. THREE‐
THREE‐
WINDING
TRANSFORMER

25. AUTOTRANSFORMER

26. LARGE AUTOTRANSFORMER BANK

27. SMALL AND MEDIUM‐SIZED
SMALL AND MEDIUM‐
MOTORS < ABOUT 1 MW
 With ff ti l ‐resistance earthed
With effective or low‐ i t
With effective or low th d
infeed (IE ≥ INMotor)

28. SMALL AND MEDIUM‐SIZED
SMALL AND MEDIUM‐
MOTORS < ABOUT 1 MW
 With hi h‐resistance earthed infeed
With high
With high‐ i t th d i f d
(IE≤INMotor)

29. LARGE HV
MOTORS
> ABOUT
1 MW

30. COLD LOAD
PICKUP

31. GENERATORS
< 500 KW

32. GENERATORS, TYPICALLY 1–3 MW
GENERATORS, TYPICALLY 1–

33. GENERATORS > 1–3 MW
GENERATORS > 1–

34. GENERATORS > 5–
GENERATORS > 5–10 MW FEEDING INTO A
NETWORK WITH ISOLATED NEUTRAL

35. GENERATORS
>50‐
>50‐100 MW
IN GENERATOR
TRANSFORMER
UNIT
CONNECTION

36. SYNCHRONIZATION OF A
GENERATOR

37. BUSBAR PROTECTION BY O/C RELAYS
WITH REVERSE INTERLOCKING

38. HIGH‐
HIGH‐IMPEDANCE BUSBAR
PROTECTION

39. LOW‐
LOW‐IMPEDANCE BUSBAR
PROTECTION 7SS60

40. LOW‐
LOW‐IMPEDANCE BUSBAR
PROTECTION 7SS52