calculations considering different operational states as well as time delay co-
ordination with other protections in the system. As a second protection a residual
voltage protection is often used.
• Failure of the circuit beaker to interrupt fault current after protection trip. The breaker
failure protection function is essential in a protection system using local redundancy.
• Autoreclosing is normally used on power lines as most faults are transient, that is the
arcing fault will extinguish after a short zero voltage interval.
The recommendations in table
1 have the following meaning:
• Enabled: It is recommended to have the function activated in the application
• Disabled: It is recommended to have the function deactivated in the application
• Application dependent : The decision to have the function activated or not is
dependent on the specific conditions in each case
Application 1 and Application 2 in table 1 are according to application
examples given in previous sections.
Table 1: Functionality table
Function
Application 1 Application 2
Instantaneous phase overcurrent protection ,
3-phase output PHPIOC (50)
Enabled Enabled
Four step phase overcurrent protection, 3-
phase output OC4PTOC (51_67)
Enabled Enabled
Instantaneous residual overcurrent
protection EFPIOC(50N)
Enabled Disabled
Four step residual overcurrent protection
EF4PTOC (51N_67N)
Enabled Disabled
Sensitive directional residual overcurrent and
power protection SDEPSDE (67N)
Disabled Enabled
Thermal overload protection, one time
constant, Fahrenheit LFPTTR/LCPTTR (26)
Fahrenheit/Celsius
Application dependent
Application dependent
Application dependent
Breaker failure protection, 3-phase activation
and output CCRBRF (50BF)
Enabled Enabled
Pole discordance protection CCRPLD (52PD) Application dependent Application dependent
Broken conductor check BRCPTOC (46) Application dependent Application dependent
Directional under-power protection
GUPPDUP (37)
Application dependent Application dependent
Table continues on next page
Section 2 1MRK 511 286-UUS A
Application
34
Application manual
To Next Page
Loading...
