70 – Pvd3665_Gb_Ex_August 2022
3.2.12. Voltage withstand characteristics of EX series
The motors fed by converters are subject to higher stresses than in case of sinusoidal power
supply. The combination of fast switching inverters with cables will cause overvoltage due
to the transmission line effects. The peak voltage is determined by the voltage supply, the
length of the cables and the voltage rise time. As an example, with a rise time of 200 ns and
a 30 m (100 ft) cable, the voltage at the motor terminals is twice the inverter voltage.
The insulation system of the servomotors EX is designed to withstand high repetitive pulse
voltages and largely exceeds the recommendations of the IEC/TS 60034-25 ed 2.0 2007-
03-12 for motors without filters up to 500V AC (See figure 1).
Figure 1: Minimum Voltage withstands characteristics for motors insulations according to
IEC standards. At the top are the typical capabilities for the EX motors.
Note: The pulse rise times are defined in accordance with the IEC/TS 60034-17 ed4.0 2006-
05-09.
The EX motors can be used with a supply voltage up to 480 V under the following conditions:
▪ The pulse rise times must be longer than 50 ns.
▪ The repetitive pulse voltages must not exceed the values given in figure 1, “Curve EX
motors” in dark blue.