Page 80 - Sace Emax 2 Manual for design engineers

ABB | SACE Emax 2
7 - 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 Function
ROCOF protection protects against rapid frequency variations: the protection sends a TRIP command if the
t frequency changes faster than control variation f28 set in the unit for longer than t28.
f28 ROCOF

f(Hz) Frequency variation
t28 after failure (1)

Frequency fluctuation
Hz/s
(after a failure)
f28
f mis

t28 t(s)
Figure 25

(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 93)
• the graph with trip curve (page 109)
Parameters
Parameter Description Default
Activates/deactivates the protection and its availability in the parameters
Enable OFF
menu
Activates/deactivates transmission of the open command: if disabled, the
Trip Enable OFF
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 0,6 Hz/s
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 Up or Down
(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 0,5 s
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 83).

78 | © 2020 ABB | 1SDH001330R1002 - ECN000134959 - Rev. A Ekip Touch - Protections | 7 - ROCOF protections