ABB ACS880 - Settings and Diagnostics; Thermal Protection of Motor Cable; User Load Curve

Parameters specific to motor overload protection: 35.5 Motor overload
level (page 398), 35.56 Motor overload action … 35.57 Motor overload class (page 408).
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Thermal protection of motor cable
The control program contains a thermal protection function for the motor cable.
This function should be used, for example, when the nominal current of the drive
exceeds the current-carrying capacity of the motor cable.
The program calculates the temperature of the cable on the basis of the following
data:
• Measured output current (parameter 1.7)
• Nominal continuous current rating of the cable, specified by 35.61, and
• Thermal time constant of the cable, specified by 35.62.
When the calculated temperature of the cable reaches 102% of the rated maximum,
a warning (A480) is given. The drive trips on a fault (4000) when 106% is reached.
Settings and diagnostics
Parameters: 35.60 Cable temperature...35.62 Cable thermal rise time (page 409).
Events: A480 Motor cable overload (page 672) and 4000 Motor cable
overload (page 657).
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User load curve
The user load curve provides a function that monitors an input signal (eg. motor
torque or motor current) as a function of drive output speed or frequency. The
function includes both high limit (overload) and low limit (underload) monitoring.
Overload monitoring can, for example, be used to detect a pump becoming clogged
or a saw blade hitting a knot. Underload monitoring can detect the load being lost,
for example because of the snapping of a transmission belt.
The monitoring is effective within a motor speed and/or frequency range. The
frequency range is used with a frequency reference in scalar motor control mode;
otherwise, the speed range is used. The range is defined by five speed (parameters
37.11…37.15) or frequency (37.16…37.20) values. The values are positive, but the
monitoring is symmetrically active in the negative direction as the sign of the
monitored signal is ignored. Outside the speed/frequency range, the monitoring
is disabled.
An underload (37.21…37.25) and overload (37.31…37.35) limit is set for each of the
five speed or frequency points. Between these points, the limits are interpolated
linearly to form overload and underload curves.
Program features 133