1st edition, 12.02.2021
7000.05071, 1st edition, 12.02.2021
7000.05071
Installation
66
Parasitic current usually arises from the following components:
Semiconductors
Capacitive portion of the motor supply line
Parasitic elements in the motor
Operating the motors with PWM is the cause here.
The DC-DC converter in the device and the used switching power supply also produce inter-
ference that could affect the mains. The created interference of the DC-DC converter in the
device is, however, normally of little relevance due to the switched power (<5 W).
In contrast to this are the switching power supply, which supplies the controller with motor
voltage or electronics voltage, and the PWM drive. Depending on the design, quality and
effectiveness of the integrated filters (where present), the power supply can also cause
interference.
DC-mains system
Prerequisite for connecting to the DC mains is that the switching interference of the power
supply be negligible. A linear power supply can be used to reduce this interference.
Problem solutions
The interference may vary depending on load and installation.
The mentioned variants are effective only if the following chapters are followed correctly.
The qualitative assessment of a power supply can be performed with an interference
voltage test and a resistive load (e.g., fanless heater / hot plate).
Solution
Mode of action
Benefits
Disadvantages
3-phase common-mode
choke / ferrite ring around
all motor phases
Removes common-mode
interference of the
motor
Removes RF common-
mode interference
Fast testing possible
Does not remove all inter-
ference
Fabrication necessary
PWM motor filter
(e.g., EFM 5003 6501.0035
7)
Removes switching noise
on the motor cable
through DC averaging
Interference limited to
input side
Does not remove all RF inter-
ference
Motor filters and ferrites
(e.g., EFC 5008 6501.00351
)
Removes RF interference
on the motor cable
Optimum for radio emis-
sions
Does not remove all low-fre-
quency interference
Input filter upstream of
the controller
(e.g., EFS 5004 6501.00350
)
Removes interference of
the switching regulator
and part of the motor
interference on DC net-
works
Pass an interference volt-
age measurement with
correct wiring
Does not remove interference
on the motor side
Mains filter upstream of
the switching power
supply
Removes common-mode
interference of the
power supply
Very cost-effective solu-
tion
Often only effective for
power supply
Does not remove all inter-
ference