Guidelines for planning the electrical installation 55Additional data for calculating the rise time and the peak line-to-line voltageThe diagrams below show the relative peak line-to-line voltage and rate of change ofvoltage as a function of the motor cable length with and without a du/dt filter in use.To calculate the actual peak voltage for a certain cable length read the relative ÛLL /UNvalue from the appropriate diagram and multiply it by the nominal supply voltage (UN ).To calculate the actual voltage rise time for a certain cable length read the relative valuesÛLL/UN and (du/dt)/U N from the appropriate diagram. Multiply the values by the nominalsupply voltage (U N ) and substitute into equation t = 0.8 · ÛLL/(du/dt).Additional note for common mode filtersCommon mode filters are available as plus code option +E208.Selecting the power cables General rulesSelect the input power and motor cables according to local regulations:• Select a cable capable of carrying the drive nominal current. See section Ratings(page 113) for the rated currents.• Select a cable rated for at least 70 °C (158 °F) maximum permissible temperature ofconductor in continuous use. For US, see Selecting the control cables, page 58.• The inductance and impedance of the PE conductor/cable (grounding wire) must berated according to permissible touch voltage appearing under fault conditions (so thatthe fault point voltage will not rise excessively when a ground fault occurs).• 600 V AC cable is accepted for up to 500 V AC.Use symmetrical shielded motor cables (see page 57). Ground motor cable shields 360° atboth ends. Keep the motor cable and its PE pigtail (twisted shield) as short as possible toreduce high-frequency electromagnetic emissions.Drive with du/dt filter Drive without du/dt filterI Motor cable lengthÛLL/UN Relative peak line-to-line voltagedu/dt /UN Relative du/dt valueNote: ÛLL and du/dt values are approximately 20% higher with resistor braking.100 200 3000.00.51.01.52.02.53.0l (m)du/dtUN-------------(1/s)ÛLL /UNÛLL /UNl (m)du/dtUN-------------(1/s)1.02.05.04.03.01.52.53.54.5100 200 3005.5
