Danfoss VLT AQUA Drive FC 202 Design Manual page 156

How to Install
c. Protection regarding earth potential between PLC
and frequency converter
If the earth potential between the frequency
converter and the PLC is different, electric noise
can occur that disturbs the entire system. Solve
this problem by fitting an equalising cable next
to the control cable. Minimum cable cross-
section: 16 mm
d. For 50/60 Hz earth loops
If long control cables are used, 50/60 Hz earth
loops are possible. Solve this problem by
5 5
connecting one end of the screen to earth via a
100 nF capacitor (keeping leads short).
e. Cables for serial communication
Eliminate low-frequency noise currents between
two frequency converters by connecting one end
of the screen to terminal 61. This terminal is
connected to earth via an internal RC link. Use
twisted-pair cables for reducing the differential
mode interference between the conductors.
154
®
VLT AQUA Drive FC 202 Design Guide
2
.
MG20Z102 - VLT
PLC etc.
PE
PLC etc.
PE
PLC etc.
PE
PE
PLC etc.
PE
100nF
FC
69
68
61
Illustration 5.109 Earthing
®
is a registered Danfoss trademark
FC
PE
a
FC
PE
b
FC
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PE
c
Min. 16mm 2
Equalizing cable
FC
PE
d
FC
68
69
PE
e