ABB SACE Tmax XT5 Operation And Maintenance Manual page 72

Protection UC Function
Protection U Function
70 | © 2019 ABB | 1SDH002039A1002 - ECN000093027 - Rev. A
UC protects the motor in reduced or no load conditions: the protection sends a TRIP command if all the
current values detected by the unit drop below threshold luc for longer than time tuc.
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 81)
• the graph with trip curve (page 96)
Parameters
Parameter Description
Activates/deactivates the protection and its availability in the
Enable
parameters menu
Activates/deactivates transmission of the open command: if disabled,
Trip Enable the alarm and exceedance of protection time are only managed as
information
Establishes the value that activates the protection.
Threshold Iuc The value is given as both absolute value (Amperes) and relative value
(Ir) and can be set within the range: 0.5 Ir to 0.9 Ir in 0.1 Ir steps
This is the trip time of the protection; the value is given in seconds and
Time Iuc
can be set within a range: 1 s to 20 s, in 0.5 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).
U protects the motor in the event of phase loss: the protection sends a TRIP command if the rms value of at
least one phase drops below the 0.1 In threshold and, at the same time, a current exceeds 0.25 for longer
than time tu; the protection is inhibited during Motor start-up.
If an alarm due to U protection occurs during Motor start-up, the trip unit calculates the trip time of the
protection using whichever is the lowest value between: tu and half of Motor start-up
IMPORTANT: in this case, if the alarm occurs on start-up and the calculated TRIP
time is sufficiently long to last even until the Motor start-up window closes, the trip
unit still considers the previously calculated minimum value as TRIP time
To check and simulate the trip times in relation to all the parameters, please consult the summary table of the
protections with the operating characteristics (page 81)
Parameters
Parameter Description
Activates/deactivates the protection and its availability in the
Enable
parameters menu
Activates/deactivates transmission of the open command: if disabled,
Trip Enable the alarm and exceedance of protection time are only managed as
information
This is the trip time of the protection; the value is given in seconds and
Time tu
can be set within a range: 1 s to 10 s, in 0.5 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).
ABB | SACE Tmax XT
Default
OFF
OFF
0,5 Ir
1 s
Default
OFF
OFF
1 s
Protections | 8 - Motor protections