5.8 Motor connection5.8.1 General information• The motor cables must be designed to the maximum continuous current.• They are valid for 0...100 Hz (up to 300 Hz the cable losses increase by approx.25% due to the skin effect).• The IGBT modules cause high-frequency interferences which cause a stronger der-ivation into the earth potential with increasing motor cable length.• The consequence is an increase of the cable-based interferences on the line side.• If the motor cables are too long, the damping of the mains filter is no longer sufficientand the permitted interference limits are exceeded.• At the output of the drive converter, pulses with approx. 1.35-fold of the mains volt-age and very short rise times are generated independently of the output frequency.• This is the case for all drive converters with modern IGBT drive converter technology.• The voltage of the pulses can be almost double at the motor terminals, dependingon the motor cable properties.• This can lead to additional load on the motor and motor cable insulation.• Modern speed-controlled drives with its rapidly rising voltage pulses and high switch-ing frequencies can cause current pulses which run through the motor bearings andlead to a gradual damage of the bearing raceways.ATTENTION Protect motor against voltage peaks !► The connecting-up instructions of the motor manufacturer are al-ways generally valid !► Inverter switch at the output with high voltage rise speed see „Tech-nical Data“. Voltage peaks that endanger the insulation system atthe motor can occur especially in case of long motor cables (> 15m). A motor choke, a du/dt filter as well as a sine-wave filter can beused to protect the motor.5.8.2 connection motor cableATTENTION By default, all 690 V motors are connect in star connection.53eLecTrIcAL INSTALLATION
