Engineering Guide CDA3000
3-23
3 Selection of inverter module
DE
EN
1
2
3
4
5
6
7
A
Please note that the mains power cable and fuses used must conform to
the specified listings (such as cUL).
Minimum cross-section of the grounding lead to VDE 0100
Part 540
3.2.4 Operation of
fault current
breakers
In operation of the inverter, because of the internal suppression capaci-
tors, the high clock frequencies, the parasitic capacitors, the power stage
of the parasitic capacitors, the motor cable and the radio interference sup-
pression filters the leakage current is > 3.5 mA. In individual cases it may
be several hundred mA.
The inverter module must therefore always be thoroughly grounded (VDE
0100 Part 540, EN 50178) in order to conform to the provisions regarding
increased leakage currents applicable above 3.5 mA.
Fault current breakers must be used in accordance with local regulations.
It should however be noted that, due to the three-phase input rectifier, the
leakage current contains a DC component and short-term pulse-shaped
leakage currents occur on power-up.
Only all-current sensitive fault current breakers suitable for inverter
operation may be used.
The fault current breaker must meet the following conditions:
• Suitable for protection of devices with DC component in the lea-
kage current (only with three-phase rectifier bridge)
• Suitable for short-term pulse-shaped leakage currents
• Suitable for high leakage currents
Cross-section PE mains connection
Mains power cable
< 10 mm
2
Grounding lead (PE) cross section of at least 10 mm or lay a
second electrical conductor parallel to the existing grounding
lead, because the operational leakage current is > 3.5 mA.
Mains power cable
>10 mm
2
PE conductor with cross-section of mains power cable - see VDE
0100 Part 540
Table 3.18 Minimum cross-section of the grounding lead
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