Chapter 2: Installation
24 2X Series Installation Manual
Connections
Recommended cables
Recommended cables for optimal system performance are shown in the table
below.
Table 9: Recommended cables
Twisted-pair (52 Ω and 500 nF max.) [1]
12 to 26 AWG (0.13 to 3.31 mm²)
2 km with KAL21 cable [2]
Other types of cable may be used subject to site-specific electromagnetic
interference (EMI) conditions and installation testing.
Using shielded loop cable
In most installations shielded loop cable is not required and the system has been
validated to operate in standard conditions with unshielded twisted-pair cable.
However, shielded cable provides more flexibility in solving site-specific EMI
problems and may be used, subject to following these guidelines:
• Use a multimeter to check that the shield is fully isolated from earth, the loop
positive, and the loop negative lines before connecting the shield to a single
point in the installation. The same isolation must be provided for any other
site wiring and loop cabling should avoid any known sources of EMI at the
site.
• Use the earth studs in the control panel cabinet (if you need to reduce
interference). See Figure 4 on page 17 or Figure 5 on page 18 for the location
of the earth studs.
The PCB terminal earthing connections only improve noise immunity in very
specific environmental conditions. In some cases, leaving the earth fully
isolated provides the best protection against EMI.
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