ABB UNITROL 1020 - Electrical Installation; Digital and Analog IO Cabling 1020; Inrush Current of UNITROL 1020

 Chapter 4 - Installation and Storage
UNITROL 1020 User Manual 3BHS335648 E82 81
4.5 Electrical Installation
The emission limits in accordance with standard EN 61000-6-4 will only
be complied with if the connections for the power electronics supply and
the field output are made using shielded cables grounded at each end.
We also recommend that shielded cables be used for the analog and
digital connections.
The connection terminals are fitted on the front side of the unit, on three
levels:
Cross sections
- Power electronics, terminal numbers 1 to 17
0.2 to 4 mm
2
(AWG 24 to 10)
- Electronic sections, terminal numbers 20 to 77
0.2 to 2.5 mm
2
(AWG 24 to 12)
The casing must be grounded at terminal 17 with 4 mm
2
. Additional earth
terminals are provided for the shielded cables. The ground connection
should be kept as short as possible.
NOTICE!
Excitation cables longer than 3 m should be shielded. If not, there is
a risk of severe EMI-distortion.
4.5.1 Digital and analog IO cabling 1020
Digital and analog IOs are referenced to PE, meaning analog and digital
ground (Dx / BOx) is connected directly to PE.
Therefore the maximum cable length is limited to 30m.
In addition the following recommendations shall be followed:
 <3m: none
 3-10m: Twisted pair cable
 10-30m: Shielded cable with one PE connection close to the
UNITROL 1000 device.
 >30m: not allowed
Digital and analog IO cables must be separated from any power or
measurement cable
4.5.2 Inrush current of UNITROL 1020
Due to the large internal DC capacitor the inrush current might become
very high especially with a strong voltage source.