ABB | SACE Tmax XT
Protections | 12 - ROCOF protections
69 | © 2020 ABB | 1SDH001821A1002 - ECN000135670
12 - ROCOF protections
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:
ROCOF Protection
f28
t
t28
Hz/s
ROCOF
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.
f(Hz)
Frequency fluctuation
(after a failure)
Frequency variation
after failure
(1)
t
28
t
(s)
f
28
f
mis
Figure 30
(1)
example with positive linear variation of the higher frequency of the set f28 value; the protection also
manages negative variations
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 89)
• the graph with trip curve (page 106)
Parameters
Parameter
Description
Default
Enable
Activates/deactivates the protection and its availability in the parameters
menu
OFF
Trip Enable
Activates/deactivates transmission of the open command: if disabled, the
alarm and exceedance of protection time are only managed as information
OFF
Threshold f28
establishes the maximum admissible frequency variation rate over time; the
protection trips if this rate is exceeded.
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
0,6 Hz/s
Trip Direction
Establishes whether the protection monitors an increase (
Up
), a decrease
(
Down
) or both variations (
Up
and
Down
)
Up or Down
Time f28
This is the trip time of the protection; the value is given in seconds and can
be set within a range: 0.06 s to 300 s, in 0.01 s steps
0,5 s
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 78).
