Standard program features 123The program calculates the temperature of the cable on the basis of the followingdata:• Measured output current (parameter 01.07 Motor current)• Nominal continuous current rating of the cable, specified by 35.61 Cable nominalcurrent, and• Thermal time constant of the cable, specified by 35.62 Cable thermal rise time.When the calculated temperature of the cable reaches 102% of the rated maximum,a warning (A480 Motor cable overload) is given. The drive trips on a fault (4000 Motorcable overload) when 106% is reached.SettingsParameters 35.60…35.62 (page 331). User load curveThe user load curve provides a function that monitors an input signal (e.g. motortorque or motor current) as a function of drive output speed or frequency. Thefunction includes both high limit (overload) and low limit (underload) monitoring.Overload monitoring can, for example, be used to detect a pump becoming cloggedor a saw blade hitting a knot. Underload monitoring can detect the load being lost, forexample because of the snapping of a transmission belt.The monitoring is effective within a motor speed and/or frequency range. Thefrequency 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 (parameters37.11…37.15) or frequency (37.16…37.20) values. The values are positive, but themonitoring is symmetrically active in the negative direction as the sign of themonitored signal is ignored. Outside the speed/frequency range, the monitoring isdisabled.An underload (37.21…37.25) and overload (37.31…37.35) limit is set for each of thefive speed or frequency points. Between these points, the limits are interpolatedlinearly to form overload and underload curves.
