Thermal Protection Of Motor Cable; User Load Curve - ABB ACS880 Firmware Manual



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
• Nominal continuous current rating of the cable, specified by
current, and
• Thermal time constant of the cable, specified by
When the calculated temperature of the cable reaches 102% of the rated maximum,
a warning (A480 Motor cable
cable overload) when 106% is reached.
Settings
Parameters 35.60...35.62
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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.
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01.07 Motor
overload) is given. The drive trips on a fault
(page 297).
Program features 83
current)
35.61 Cable nominal
35.62 Cable thermal rise time.
(4000 Motor