Preparing For Installation - ABB ACS550-02 User Manual

6

Preparing for Installation

Checking the Compatibility of the Motor
See Technical data for the drive ratings and the motor connection data.
WARNING! Operation is not allowed if the motor nominal voltage is less than 1/2 of
the drive nominal input voltage, or the motor nominal current less than 1/6 of the
drive nominal output current.
Protecting the Motor Winding and Bearings
The output of the drive comprises – regardless of output frequency – pulses of
approximately 1.35 times the mains network voltage with a very short rise time. This
is the case with all drives employing modern IGBT inverter technology.
The voltage of the pulses can be almost double at the motor terminals, depending on
the motor cable properties. This in turn can cause additional stress on the motor
insulation.
Modern variable speed drives with their fast rising voltage pulses and high switching
frequencies can cause current pulses through the motor bearings which can
gradually erode the bearing races.
To avoid damage to motor bearings, insulated N-end (non-driven end) bearings and
output filters from ABB are recommended according to the following table. In
addition, the cables must be selected and installed according to the instructions
given in this manual. Three types of filters are used individually or in combinations:
• optional du/dt limitation (protects motor insulation system and reduces bearing
currents).
• common mode filter (reducing bearing currents)
The common mode filter is composed of toroidal cores installed onto the output
busbars inside the drive at the factory.
Installation