10
INM MTL SUM5 Rev 1
4.6 DC power connection
Single or dual-redundant 24V (nom.) DC power supplies can be connected to each
backplane using a removable, 4-way, screw-clamp terminal connector. Dual supplies
are connected in parallel through diodes on the backplane, and bussed to the individual
isolators. LEDs on the backplane will illuminate to show if the two independent supplies
are operational. The use of diodes between the two supplies means that the one with
the higher voltage is used at any given moment, and will ensure automatic switchover of
supplies if one source fails.
The screw terminal connections for the power cables are suitable for cables 0.5mm
2
-
4 mm
2
rigid core or 0.5mm
2
- 2.5mm
2
stranded.
NOTE
Cable ferrules to DIN 46228 standard must be fitted to any stranded cable or
screen wiring that is being used.
Ferrules of length 10mm are recommended for use on the power supply terminal blocks.
Figure 4.5
- Power supply wiring
V1 V2 0V 0V
Supply 1
24V dc
24V dc
Supply 2
-
-
+
+