Parameter descriptions
7.10.6.2 Motor Protection by I
2
t- monitoring
571 Operation Mode (I
2
t- monitoring)
To protect the motor against overload the I
2
t monitoring provides a further possibility for the user.
This kind of motor protection is mainly used in servo technology.
When using servo motors the I
2
t- monitoring is a proven alternative to motor protection switch.
By integrating temperature-dependent parameters, measurable or known, the heating of a mathemati-
cal model is simulated. The kind of the I
2
t monitoring mode can be selected by Operation Mode 571.
This parameter is switchable via data set.
The I²t monitoring works by function (I
act
/I
n
)² as shown in the figure.
The monitored value is evaluated via a PT1 element with the thermal time constant of the stator.
If the output of PT1 element is bigger than 120%, then an error message is generated and the drive
switches off. The threshold of 120% prevents, that an overshoot leads to an immediate shutdown.
In the application should be avoided exceeding 100% capacity of the stator winding permanently.
The output of the first PT1 element is linked to the input of the second PT1 element which includes
the thermal motor time constant. This output may be permanently 100%.
This corresponds to the complete thermal capacity of the motor. If 102% is reached, the drive
switches off with an error message. Both outputs are connected to the adjustable alarm limit.
42 – I²t, Single-Motor,
Error Switch Off
The I²t capacity of the motor is monitored with rat-
ed values from the active dataset.
If the fixed threshold values exceed 100%
motor
(120%
stator
), the drive switches off with fault
"F0401" in the active dataset.
51 – I²t, Multi-Motor Operation,
Warning
The I²t capacity of the motors regarding their relat-
ed ratings is monitored in
sets. If the Warning Limit Motor I
2
t 615 is reached,
the warning message "A0200" is signaled from the
active data set.
52 – I²t, Single-Motor,
Warning
The I²t capacity of the motor is monitored with rat-
ed values from the active dataset.
If the Warning Limit Motor I
2
t 615 is reached, the
warning message "A0200" is signaled from the ac-
tive data set.
248
Operating Instructions
Agile
06/2013 Special functions
To Next Page
Loading...
Need help?
General
