Du/Dt And Common Mode Filtering; What This Chapter Contains; When Is Du/Dt Or Common Mode Filtering Required - ABB ACQ810-04 Hardware Manual

du/dt and common mode filtering 105

du/dt and common mode
filtering

What this chapter contains

This chapter describes how to select du/dt and common mode filtering for the
ACQ810-04. The chapter also contains the relevant technical data.

When is du/dt or common mode filtering required?

The output of the drive comprises – regardless of output frequency – pulses of
approximately 1.35 times the equivalent supply 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. Common mode filtering mainly reduces
bearing currents.
To avoid damage to the motor bearings, the cables must be selected and installed
according to the instructions given in chapter Electrical installation. In addition, du/dt
filtering, common mode filtering, and insulated N-end bearings must be used
according to the following table.