Hardware reference guide
Pwr. & Grnding. Guide
35013379 02 October 2007 789
The proper method for starting systems powered by summable power supplies is to 
insert both supplies in the backplane in an unpowered state, and then apply power 
to each supply. For 140CPS11410, 140CPS21400, and 140CPS414 models, there 
is no requirement to power each supply simultaneously. For 140CPS11420, or 
wherever this module is operated with a 140CPS11410, the delay between the two 
powering times should not be greater than five seconds. The system designer must 
realize that the operation of the summable supply described above is independent 
of total backplane load, i.e., even if the total load on the backplane is less than 8 A, 
if there are two summable supplies installed in the backplane, the system POK is 
generated as shown in this section.
For the special case of a single summable supply used as a standalone, the system 
POK generation reverts to the standalone case as shown previously in this section.
Redundant 
Power Supplies
Five redundant power supply models are offered.
Similar to the summable supplies, the Quantum redundant power supplies also 
contain circuitry which forces the installed power supplies to share output current 
almost equally. An important difference between the summable and the redundant 
supply lies in the system POK generation circuitry. 
The Quantum system POK signal in systems powered by redundant power supplies 
is true (power is OK) if either or both internal POK is true. The following figure shows 
the internal Quantum redundant supply POKs are ORed to create the Quantum 
System POK. 
• 140CPS12400 115 ... 230 Vac input 8 A output
• 140CPS12420 115 ... 230 Vac input 10 A output
• 140CPS22400 24 Vdc input 8 A output
• 140CPS42400 48 Vdc input 8 A output
• 140CPS52400 125 Vdc input 8 A output
Note: Redundant power supply module health may be monitored in an I/O module 
health status word. (Refer to the STAT Block description in Modicon Ladder Logic 
Block Library User Guide, 840USE10100.)
Quantum
System
POK
Redundant CPS
Internal POK
Redundant CPS
Internal POK
OR
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