Planning the electrical installation
39
Protecting the motor insulation and bearings
The output of the drive comprises – regardless of output frequency – pulses of
approximately 1.35 times the equivalent 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 attenuation and reflection properties of the motor cable and the terminals. This in
turn can cause additional stress on the motor and motor cable insulation.
Modern variable speed drives with their fast rising voltage pulses and high switching
frequencies can generate current pulses that flow through the motor bearings, which
can gradually erode the bearing races and rolling elements.
The stress on motor insulation can be avoided by using optional ABB du/dt filters.
du/dt filters also reduce bearing currents.
To avoid damage to motor bearings, the cables must be selected and installed
according to the instructions given in the hardware manual. In addition, insulated N-
end (non-drive end) bearings and output filters from ABB must be used according to
the following table. Two types of filters are used individually or in combinations:
• optional du/dt filter (protects motor insulation system and reduces bearing
currents).
• common mode filter (mainly reduces bearing currents).
Summary of Contents for ACS800-U7
Page 1: ...ACS800 Hardware Manual ACS800 07 Drives 45 to 560 kW ACS800 U7 Drives 50 to 600 hp ...
Page 4: ......
Page 28: ...Operation principle and hardware description 28 ...
Page 51: ...Planning the electrical installation 51 ...
Page 60: ...Planning the electrical installation 60 ...
Page 76: ...Electrical installation 76 ...
Page 84: ...Motor control and I O board RMIO 84 ...
Page 112: ...Maintenance 112 ...
Page 138: ...Dimensional drawings 138 Frame sizes R5 and R6 64778340_1 5 K ...
Page 139: ...Dimensional drawings 139 Frame sizes R7 and R8 68749930_1 7 C ...
Page 140: ...Dimensional drawings 140 IP54 and IP54R units of frame sizes R7 and R8 68749930_6 6 C ...
Page 148: ...3AFE64702165 Rev H EN 2012 09 19 Contact us www abb com drives www abb com drivespartners ...