Cable installation in ac-
cordance with EMC
Signal and bus cables are susceptible to interference.
Motor cables are interference sources.
●
Lay cables being susceptible to interference or sources of interference at the
highest possible distance from each other.
●
The interference immunity of signal and bus cables increases if the cables are
laid close to the ground potential.
●
If possible, avoid laying long cables and make sure that they are installed in
areas being subject to low interference.
●
Avoid long parallel paths with cables being either susceptible to interference or
interference sources.
●
For the connection of remote position transmitters, screened cables must be
used.
Type of current, mains
voltage and mains fre-
quency
Type of current, mains voltage and mains frequency must match the data on the
motor name plate.
Figure 10: Motor name plate (example)
[1] Type of current
[2] Mains voltage
[3] Mains frequency (for 3-ph and 1-ph AC motors)
Connecting cables
For device insulation, appropriate (voltage-proof) cables must be used. Specify
cables for the highest occurring rated voltage or physically separate the cables as
required.
Use connecting cable with appropriate minimum rated temperature.
When specifying the connection cables, consider UV radiation.
Bus cables
Only cables complying with the recommendations of EIA 485 specifications should
be used for Modbus wiring.
Cable recommendation:
Impedance:
135 to 165 Ohm, at a measurement frequency bet-
ween 3 and 20 MHz
Cable capacity:
< 30 pF per metre
Wire diameter
> 0.64 mm
Wire cross section:
0.34 mm², corresponds to AWG 22
Loop resistance:
< 110 Ohm per km
Screening:
CU shielding braid or shielding braid and shielding
foil
Prior to installation, please note:
●
Connect maximum 32 devices to one segment.
●
If more devices are to be connected:
- Connect several segments using repeaters.
●
Respect a distance of minimum 20 cm between the bus cable and other cables.
17
SG 05.1 – SG 12.1/SGR 05.1 – SGR 12.1 Control unit: electromechanic
AC 01.1 Intrusive Modbus RTU Electrical connection