7
INM4500-2
Mar 2009
4.4.3 Interconnecting power supplies for multiple 8- and 16-way backplanes
Power supplies for 8- and 16-way backplanes can be interconnected in the form of a ring. This will reduce
wiring and also permit individual backplanes to be taken out of service without affecting supplies to other
backplanes. More than one backplane can be removed, provided that they are neighbours and do not
leave any other backplanes without an active supply. The connections are shown in Figure 4.11.
Note:
a mixture of 8- and 16-way backplanes can be interconnected, provided that the maximum
circuit current does not exceed 12A. Wire sizes up to 2.5mm
2
(14 AWG) can be used and should
be chosen according to calculated current load and voltage drop.
4.4.4 Safe area – discrete power supply connections (24-way backplanes)
Dual-redundant 24V DC power supplies can be connected to each backplane using plug-in connectors.
The supplies are connected in parallel, through diodes, and bussed by the backplanes to individual
isolators. LEDs on the backplane will light if the two independent supplies are operational. The diodes
between the two ensures that the highest voltage supply is the one in use at any given moment, and
providing automatic switchover of supplies if one source fails
Connect the power supply cables to the connector according to the pin assignments shown in
Figure 4.12. The maximum permissible wire size is 2.5mm
2
(14 AWG).
Plug the power supply connector into the base connector on the backplane.
The rating of the fuse is:–
24-way: 3.15A
(FUS24 fuse kit)
4.5 Backplanes – customised
For information about installing customised backplanes (whether supplied by MTL or by a third party),
see the separate instructions provided with the units.
a)
b)
c)
12 10 8
11 9 7
2
1
Top
view
Edge
view
12 10 8
11 9 7
12 10 8
11 9 7
0V PWR1
0V PWR2
Primary
Power
Supply
+
Secondary
Power
Supply
SKT 1
SKT 2
PWR 1
PWR 2
+
0V
Primary
Power
Supply
+
Secondary
Power
Supply
+
PWR2
PWR1
23
24
Figure 4.9:
Terminal pin
assignments
Figure 4.10:
PSU connections
8- & 16-way
Figure 4.12:
PSU connections
24-way
1 2 3 4 5 6 7 8
BPS4508
1 2 3 4 5 6 7 8
BPS4508
+
PSU
This ring wiring
configuration can
be repeated for
the PWR2 supply
0V
0V
+
+
1 2 3 4 5 6 7 8
BPS4508
PWR1
Figure 4.11:
Terminal pin
assignments