Specifications

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6.4.6 Motor Bearing Currents

All motors installed with FC 102 90 kW or higher power

frequency converter should have NDE (Non-Drive End)

insulated bearings installed to eliminate circulating bearing

currents. To minimise DE (Drive End) bearing and shaft

currents, proper grounding of the frequency converter,

motor, driven machine, and motor to the driven machine

is required.

Standard Mitigation Strategies

1. Use an insulated bearing.

2. Apply rigorous installation procedures

2a Ensure the motor and load motor are

aligned.

2b Strictly follow the EMC Installation

guideline.

2c Reinforce the PE so the high frequency

impedance is lower in the PE than the

input power leads.

2d 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.

2e 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.

2f Make a direct ground connection

between the motor and load motor.

3. Lower the IGBT switching frequency.

4. Modify the inverter waveform, 60° AVM vs.

SFAVM.

5. Install a shaft grounding system or use an

isolating coupling.

6. Apply conductive lubrication.

7. Use minimum speed settings if possible.

8. Try to ensure the line voltage is balanced to

ground. This can be difficult for IT, TT, TN-CS or

Grounded leg systems.

9. Use a dU/dt or sinus filter.

6.5

Control Cables and Terminals

6.5.1 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 6.43).

130BT304.10

Illustration 6.43 Enclosure Types A1, A2, A3, B3, B4, C3 and C4

130BT334.10

Illustration 6.44 Enclosure Types A5, B1, B2, C1 and C2

6.5.2

Control Cable Routing

Tie down all control wires to the designated control cable

routing as shown in the picture. Remember to connect the

shields in a proper way to ensure optimum electrical

immunity.

Fieldbus connection

Connections are made to the relevant options on the

control card. For details see the relevant fieldbus

instruction. The cable must be placed in the provided path

Electrical Installation

Design Guide