Emerson ROC827 - Manual (Page 55)

ROC827 Instruction Manual
Issued Mar-06 Power Connections 3-11
3.2.1 Tuning the Configuration
The PM-12 Power Input module can supply a maximum of 36 W (36000
mW) to the backplane, which includes the +T overhead. The PM-24,
when operating between –40
°C to 55°C, can supply a maximum of 30 W
(30000 mW) to the backplane. Across its entire operating range (–40
°C to
85
°C) the PM-24 can supply 24 W (24000 mW).
Refer to Table 3-5 and the value you entered in the Total for ROC827
Base Unit and All Modules line. That is the value against which you
“tune” your configuration to accommodate your Power Input module. If
your configuration requires more power than the Power Input module you
intend to use, you need to modify your I/O module configuration to
reduce your power requirements.
Tuning Hints Review the content of Tables 3-6 through 3-15. Suggestions to help
you better align the configuration of your ROC827 with the capability
of the Power Input module you intend to use include:
ƒ Reduce the +T usage by providing an external power supply for as
many transmitters or field devices needed to reduce the value in the
Total for ROC827 Base Unit and All Modules line on Table 3-5 to
below the capability of the Power Input module you intend to use.
ƒ Reduce the +T usage by reducing the number of transmitters or field
devices.
ƒ Reduce the total number of I/O modules by consolidating transmitters
or field devices onto as few I/O modules as possible.
Note
: Tuning your I/O module configuration may require several
iterations to rework the content of Tables 3-6 through 3-15 until your
power requirements match the capability of the Power Input module you
intend to use.