9.1.3 Noise Emission of the Drive System
Causes of noise emission
Controlled variable-speed drives contain converters containing snappy
semiconductors. The advantage of modifying the speed with high precision is
achieved by means of pulse width modulation of the converter voltage. This can
generate sinusoidal current with variable amplitude and frequency in the motor.
The steeper voltage rises, the higher clock rate and the resulting harmonics
cause unwanted but physically unavoidable emission of interference voltage and
interference fields (wide band interference). The interference mainly is
asymmetric interference against ground.
The propagation of this interference strongly depends on:
● configuration of the connected drives
● number of the connected drives
● conditions of mounting
● site of installation
● radiation conditions
● wiring and installation
If the interference gets from the device to the connected lines in unfiltered form,
these lines can radiate the interference into the air (antenna effect). This applies
to power lines, too.
Limit values for line-based disturbances
According to IEC EN 61800-3 or CISPR 11 (corresponds to EN 55011), the limit
values in the table below are distinguished. For this documentation both
standards are combined in the limit value classes A2.1 to B1.
EFC x610 Series
Bosch Rexroth AG
Electromagnetic Compatibility (EMC)
DOK-RCON03-EFC-X610***-IT05-EN-P
67/389
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