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 currents 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 distur‐
bances
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.
IEC / EN
61800-3
CISPR 11 Explanation
In this
documentation
Curves of limit
value characteristic
Category C4
2
nd
environment
None
One of the following 3 requirements must have
been fulfilled:
Mains connection current>400 A, IT mains or
required dynamic drive behavior not reached by
means of EMC filter.
Adjust limit values to use and operation on site.
User has to carry out and provide evidence of
EMC planning.
None -
Category C3
2
nd
environment
Class A
group 2
I>100 A
limit value in industrial areas to be complied with
for applications operated at supply mains with
nominal currents>100 A
A2.1
1.1
1.2
Category C3
2
nd
environment
Class A
group 2
I≤100 A
limit value in industrial areas to be complied with
for applications operated at supply mains with
nominal currents≤100 A
A2.2
2.1
2.2
Category C2
1
st
environment
Class A
group 1
limit value in residential area or at facilities at
low-voltage mains supplying buildings in
residential areas to be complied with
A1
3.1
3.2
Category C1
1
st
environment
Class B
group 1
limit value in residential areas to be complied
with
B1
4.1
4.2
Tab. 9-5: Limit values for line-based disturbances
DOK-RCON02-FV*********-IB08-EN-P Bosch Rexroth AG 177/259
Rexroth Frequency Converter Fv
Technical Data
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