1.
Use a wire stripper to remove the insulation for
proper grounding.
2.
Secure the grounding clamp to the stripped
portion of the wire with the screws provided.
3.
Secure the grounding wire to the grounding
clamp provided.
Leakage current (3.5 mA)
NOTICE
Follow national and local codes regarding protective
earthing of equipment with a leakage current > 3.5 mA.
The frequency converter technology implies high
frequency switching at high power. This generates a
leakage current in the earth connection. RFI filtering and
screened motor cables contribute to this phenomenon.
According to EN/IEC61800-5-1 (Power Drive System Product
Standard) which implies special means if the leakage
current exceeds 3.5 mA, earth grounding must be
reinforced in one of the following ways:
•
Earth ground wire, 10 mm
2
(optional accessory
required for mounting, part no. 130B5974).
•
Two separate earth ground wires both complying
with the dimensioning rules.
RCD use
A fault current in the frequency converter or at the output
power terminals can contain a DC component, and
charging of the filter capacitors can cause a transient earth
current. Where Residual Current Devices (RCDs), also
known as Earth Leakage Circuit Breakers (ELCBs), are used,
the following must be taken into account:
•
Use RCDs of type B only
•
Use RCDs with an inrush delay
•
Use RCDs of 300 mA, if possible
2.4.12 Grounding of Screened Control
Cables
Correct screening
The preferred method usually is to secure control and
cables with screening clamps provided at both ends. This
ensures the best possible high frequency cable contact.
If the ground potential between the units connected by a
control cable is different, electric noise may occur and
potentially disturb the entire system. Mitigate this problem
by fitting an equalizing conductor next to the control
cable. Use an equalizing conductor with a minimum cross-
section of 16 mm
2
.
The impedance of the equalizing conductor should
typically be maximum 10% of the impedance of the
control cable screen. See also the requirements regarding
electrical safety and grounding in
1
2
PE
FC
PE
PLC
130BB922.12
PE
PE
<10 mm
Illustration 2.21 Correct Shielding with Equalizing Cable
1
Min. 16 mm
2
(4 AWG)
2
Equalizing conductor
50/60 Hz ground loops
With long control cables, ground loops may occur. To
eliminate ground loops, connect one end of the screen-to-
ground with a 100 nF capacitor (keeping leads short).
100nF
FC
PE
PE
PLC
<10 mm
130BB609.12
Illustration 2.22 Screen-to-ground Connected to a 100 nF
Capacitor
Avoid EMC noise on serial communication
This terminal is connected to ground via an internal RC
link. To reduce interference between conductors, use
twisted-pair cables.
PE
FC
PE
FC
130BB923.12
PE
PE
69
68
61
69
68
61
1
2
<10 mm
Illustration 2.23 Recommended Method for Avoiding EMC
Noise
1
Min. 16 mm
2
(4 AWG)
2
Equalizing conductor
Alternatively, the connection to terminal 61 can be
omitted:
PE
FC
PE
FC
130BB924.12
PE
PE
69
69
68
68
1
2
<10 mm
Illustration 2.24 Screening without Using Terminal 61
Installation
VLT
®
Decentral Drive FCD 302
24
Danfoss A/S © 05/2016 All rights reserved.
MG04F402
2
2