Rocof Protections - ABB SACE Tmax XT5 Operation And Maintenance Manual

6 - ROCOF protections

ROCOF Protection
t
f28
66 | © 2019 ABB | 1SDH002039A1002 - ECN000093027 - Rev. A
The ROCOF Protection package is available by default for Ekip G Hi-Touch and configurable in the remaining
models as additional SW package
The protection is described below:
Function
ROCOF protection protects against rapid frequency variations: the protection sends a TRIP command if the
frequency changes faster than control variation f28 set in the unit for longer than t28.
ROCOF
t28
Hz/s
The protection excludes itself if the maximum value of the line-to-line voltage is less than 30 V.
To check and simulate the trip times in relation to all the parameters, please consult:
• summary table of the protections with the operating characteristics (page 80)
• the graph with trip curve (page 95)
Parameters
Parameter Description
Activates/deactivates the protection and its availability in the parameters
Enable
menu
Activates/deactivates transmission of the open command: if disabled, the
Trip Enable
alarm and exceedance of protection time are only managed as information
establishes the maximum admissible frequency variation rate over time; the
protection trips if this rate is exceeded.
Threshold f28
The value is given as absolute value (Hz/s) Fn) and can be set within the
range: 0.4 Hz/s to 10 Hz/s in 0.2 Hz/s steps
Establishes whether the protection monitors an increase (Up), a decrease
Trip Direction
(Down) or both variations (Up and Down)
This is the trip time of the protection; the value is given in seconds and can
Time f28
be set within a range: 0.06 s to 300 s, in 0.01 s steps
Limitations and additional functions
The block functions can also be accessed by means of the service connector (via Ekip Connect) or by
connection to the system bus (page 75).
f(Hz)
failure
50/60 Hz
Figure 31
ABB | SACE Tmax XT
frequency
after failure
frequency
after failure
Time
Protections | 6 - ROCOF protections
Default
OFF
OFF
0,6 Hz/s
Up or Down
0,5 s