All motors installed with AF-650 GP 90 kW or higher power drives should have NDE (Non-Drive End) insulated bearings installed to eliminate circulating bearing

currents. To minimize DE (Drive End) bearing and shaft currents proper grounding of the drive, motor, driven machine, and motor to the driven machine is required.

Standard Mitigation Strategies:

Use an insulated bearing

Apply rigorous installation procedures

Ensure the motor and load motor are aligned

Strictly follow the EMC Installation guideline

Reinforce the PE so the high frequency impedance is lower in the PE than the input power leads

Provide a good high frequency connection between the motor and the frequency converter for instance by screened cable which has a 360°

connection in the motor and the frequency converter

Make sure that the impedance from frequency converter to building ground is lower that the grounding impedance of the machine. This can

be difficult for pumps

Make a direct earth connection between the motor and load motor

Lower the IGBT switching frequency

Modify the inverter waveform, 60° AVM vs. SFAVM

Install a shaft grounding system or use an isolating coupling

Apply conductive lubrication

Use minimum speed settings if possible

Try to ensure the line voltage is balanced to ground. This can be difficult for IT, TT, TN-CS or Grounded leg systems

Use a dU/dt or sinus filter

7.6 Control Cables and Terminals

7.6.1 Access to Control Terminals

All terminals to the control cables are located underneath the terminal cover on the front of the frequency converter. Remove the terminal cover by means of a

screwdriver (see illustration).

Illustration 7.30: Unit Size 12, 13,23, 24, 33 and 34

130BT304.10

130BT334.11

Illustration 7.31: Unit Size 15, 21, 22, 31 and 32

AF-650 GP Design Guide

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