Earthing Of Screened Control Cables; Dip Switches - Danfoss VLT FCD 302 Operating Instructions Manual

Installation
1. Use a wire stripper to remove the insulation for
proper grounding.
2 2
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)
NOTE
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
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 Earthing of Screened Control Cables

Correct screening
The preferred method in most cases is to secure control
and serial communication cables with screening clamps
provided at both ends to ensure best possible high
frequency cable contact.
If the earth potential between the frequency converter and
the PLC is different, electric noise may occur that will
disturb the entire system. Solve this problem by fitting an
equalizing cable next to the control cable. Minimum cable
cross section: 16 mm
24
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®
VLT Decentral Drive FCD 302 Operating Instructions
2
(optional accessory
2
.
MG04F302 - VLT
PLC
50/60 Hz ground loops
With very long control cables, ground loops may occur. To
eliminate ground loops, connect one end of the screen-to-
ground with a 100nF capacitor (keeping leads short).
PLC
PE
100nF
Avoid EMC noise on serial communication
This terminal is connected to earth via an internal RC link.
Use twisted-pair cables to reduce interference between
conductors. The recommended method is shown below:
69
68
61
Alternatively, the connection to terminal 61 can be
omitted:
69
68

2.4.13 DIP Switches

•
Analog input terminals 53 and 54 can select for
either voltage (0-10 V) or current (0-20 mA) input
signals
•
Set switches S201 (terminal 53) and S202
(terminal 54) to select the signal type. ON is for
current, OFF for voltage
•
Terminal 53 default is for a speed reference in
open loop
•
Terminal 54 default is for a feedback signal in
closed loop
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is a registered Danfoss trademark
FC
PE PE
PE PE
Min. 16 mm²
- Equalizing cable
FC
PE
FC FC
69
68
61
PE PE
PE PE
Min. 16 mm²
- Equalizing cable
FC FC
68
69
PE PE
PE PE
Min. 16 mm²
- Equalizing cable