Electromagnetic Compatibility - Danfoss VLT CDS 803 Manual

VLT® Compressor Drive CDS 803
Design Guide
2.
Configure all required settings such as address, baud rate, and so on in parameter group 8-** Communications and Options.
For more details on parameters, refer to VLT® Compressor Drive CDS 803 Programming Guide listed in
sources.
Example
GND
68
69
Illustration 33: RS485 Wiring Connection

6.5 Electromagnetic Compatibility

Electrical devices both generate interference and are affected by interference from other generated sources. The electromagnetic
compatibility (EMC) of these effects depends on the power and the harmonic characteristics of the devices. Uncontrolled interaction
between electrical devices in a system can degrade compatibility and impair reliable operation. Interference takes the form of the
following:
• Electrostatic discharges
• Rapid voltage fluctuations
• High-frequency interference
Electrical interference is most commonly found at frequencies in the range 150 kHz to 30 MHz. Airborne interference from the drive
system in the range 30 MHz to 1 GHz is generated from the inverter, motor cable, and the motor.
Capacitive currents in the motor cable, coupled with a high dU/dt from the motor voltage, generate leakage currents. See
tion 34. Shielded motor cables have higher capacitance between the phase wires and the shield, and again between the shield and
ground. This added cable capacitance, along with other parasitic capacitance and motor inductance, changes the electromagnetic
emission signature produced by the unit. The change in electromagnetic emission signature occurs mainly in emissions less than
5 MHz. Most of the leakage current (I1) is carried back to the unit through the PE (I3), leaving only a small electromagnetic field (I4)
from the shielded motor cable. The shield reduces the radiated interference but increases the low-frequency interference on the
mains.
z
L1
z L2
z L3
z
PE
PE
3
Illustration 34: Electric Model Showing Possible Leakage Currents
52 | Danfoss A/S © 2021.05
+
RS485
C
S
U
I
1
V
W
I
2
I
3
C
S
I
4
4
C
S
1
2
I
4
5
Electrical Installation
Considerations
1.2 Additional Re-
Illustra-
C
S
C
C
S
S
6
AJ330233902305en-000201 / 130R0596