ABB | SACE Tmax XT
Protections | 14 - Motor protections
73 | © 2020 ABB | 1SDH001821A1002 - ECN000135670
Protection UC
Function
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 89)
• the graph with trip curve (page 107)
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 Iuc
Establishes the value that activates the protection.
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
0,5 Ir
Time Iuc
This is the trip time of the protection; the value is given in seconds and
can be set within a range: 1 s to 20 s, in 0.5 s steps
1 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).
Protection U
Function
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 89)
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
Time tu
This is the trip time of the protection; the value is given in seconds and
can be set within a range: 1 s to 10 s, in 0.5 s steps
1 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).
