Planning the electrical installation55Additional data for calculating the rise time and the peak line-to-line voltageThe peak line-to-line voltage at the motor terminals generated by the drive as well asthe voltage rise time depend on the cable length. The requirements for the motorinsulation system given in the table are “worst case” requirements coveringinstallations with 30 meter and longer cables.If you need to calculate the actual peak voltage and voltage rise time considering theactual cable length, proceed as follows:• Peak line-to line voltage: Read the relative ÛLL/UN value from the appropriatediagram below and multiply it by the nominal supply voltage (UN ).• Voltage rise time: Read the relative values ÛLL /UN and (du/dt)/U N from theappropriate diagram below. Multiply the values by the nominal supply voltage(U N ) and substitute into equation t = 0.8 · ÛLL /(du/dt).Additional note for sine filtersSine filters protect the motor insulation system. A factory-installed sine filter isavailable for the cabinet-installed units. The peak phase-to-phase voltage with thesine filter is approximately 1.5 × UN .Additional note common mode filtersCommon mode filter is available as a plus code option (+E208).l Motor cable lengthA Graph for calculating the rise time of units with du/dt filterB Graph for calculating the rise time of units without du/dt filterÛLL/UNdu/dtUN-------------(1/s)1.02.05.04.03.01.52.53.54.5100 200 300100 200 3000.00.51.01.52.02.53.0l (m)du/dtUN-------------(1/s)ÛLL/UN5.5l (m)A B
