Grounding - Danfoss VLT AAF006 Operating Instructions Manual

Electrical Installation
Copper affects skin less than aluminum, and bus bars have a larger surface area than cables, reducing the skin effect factor.
Proximity effects of single conductors are negligible.
The cable specifications in Table 4.2 take both skin and proximity effects into account:
Filter Minimum CU wire
190 A
70 mm
250 A
120 mm
4 4
310 A
240 mm
400 A
2*95 mm
Table 4.2 Allowed Active Filter Mains Cable with Typical Cable Manufacturer Data
Due to the built-in LCL filter, the unit does not feed the main wire with high dU/dt signals. Doing so reduces the radiated
emission through the mains cable. Cable screen/shielding can thus be omitted allowing the mains cables to be connected
without considering EMC requirements.
The active filter can run at long cable runs. Cable length is limited by the voltage drop. It is advised to keep the cable
lengths to less then 200 m.
Active filters have either built-in or customer-supplied fuses. See chapter 4.2.11 Fuses for fuse recommendations. Always
ensure proper fusing according to local regulation.

4.2.2 Grounding

Consider the following basic issues when installing an
active filter, to obtain electromagnetic compatibility (EMC):
•
Safety grounding: The active filter has leakage
current and must be grounded appropriately for
safety reasons. Apply local safety regulations.
•
High-frequency grounding: Keep the ground wire
connections as short as possible.
•
Use high-strand wire to reduce electrical
interference.
•
Do not use pigtails.
Connect the different ground systems at the lowest
possible conductor impedance. Obtain the lowest possible
conductor impedance by keeping the conductor as short
as possible and using the greatest possible surface area.
The metal cabinets of the different devices are mounted
on the enclosure back plate using the lowest possible high
frequency impedance. This avoids having different high
frequency voltages for the individual devices and avoids
the risk of radio interference currents running in
connection cables that may be used between the devices.
The radio interference is reduced. To obtain a low HF
impedance, use the fastening bolts of the devices as a
high-frequency connection to the back plate. Remove any
insulating paint or similar substances from the fastening
points.
16
Equivalent RMS
2 cable for CU
mm (AWG)
2 225 A
(2/0)
2 (4/0) 295 A
2 (500 MCM) 365 A
2 470 A
(2*3/0)
Danfoss A/S © 09/2014 All rights reserved.
Operating Instructions
Minimum ALU wire
2
mm (AWG)
2
95 mm (3/0)
150 mm 2 (300 MCM)
2*95 mm 2 (2*3/0)
2
2*150 mm (2*300 MCM)
1 Ground terminals
Illustration 4.2
Equivalent RMS Maximum wire
current for ALU
mm
240 A
2*150 mm
315 A 4x240 mm
390 A 4x240 mm
500 A
4x240 mm
2
(AWG)
2
(2*300 MCM)
2 (4x500 MCM)
2 (4x500 MCM)
2
(8x900 MCM)
1
MG90V302