Rocof Protections - ABB SACE Tmax XT2 User Manual

19 - ROCOF Protections

List The ROCOF Protection package can be configured on all models as an additional software
package. It includes:
Name
ROCOF
ROCOF Function
Protection ROCOF protection protects against rapid frequency variations: if the frequency varies faster than
the control variation f28 set in the Trip unit for a time greater than t28, the protection sends the
TRIP command.
Figure 23
The protection automatically cuts out if the maximum line-to-line voltage value is less than 30 V.
To verify and simulate the trip times based on all the parameters, see:


Parameters
Parameter
Enable
Trip Enable
Threshold
f28
Trip
direction
Time t18
Constraints, limitations, and additional functions
From the service connector (with Ekip Connect) or with system bus communication it is also
possible to access the block functions, see page70.
1SDH002031A1002 ECN000092998
Type of protection
Frequency derivative
Protection summary table with the operating characteristics (page 79)
Chart with tripping curve (page 94)
Description
Enables/disables protection and availability on menu of the
parameters
Activates/deactivates the open command: if disabled, the alarm
and the lapsing of the protection time are managed only as
information
Defines the maximum permitted frequency fluctuation rate over the
time; if the limit is exceeded, protection is tripped.
The value is expressed as an absolute value (Hz/s) Fn), settable in
a range: 0.4 Hz/s .. 10 Hz/s with 0.2 Hz/s step
Defines whether the protection monitors an increase (Up), a
decrease (Down) or both variations (Up or Down)
This is the trip time of the protection; the value is expressed in
seconds, which are settable in a range:
0.06 s .. 300 s, with 0.01 s step
Rev. B
Page
64
Default
OFF
OFF
0.6 Hz/s
Up or
Down
3 s
SACE Tmax XT2 – XT4 | 64