Replacing The Power Supply; Removal And Insertion Under Power: Potential Hazards - Honeywell ControlEdge 900 platform Hardware Planning And Installation Manual

Hazard Source
WARNING Potentially lethal voltages on Terminal
Boards associated with I/O Modules.
CAUTION Each signal at each of the terminals
for I/O Modules has a specific
function. Any or all of the signals may
be vital for safely controlling a
process.

Replacing the power supply

158
completely shutting down a running system. However, it must
be recognized that removing or inserting an I/O module under
power is potentially hazardous to property and to personnel.
CAUTION: Explosion hazard. Removal and Insertion Under Power
is not supported in Division 2/ Zone 2.
Removal and Insertion Under Power : Potential
Hazards and Recommended Actions
The power supply for the ControlEdge 900 Controller is used in all
Racks. This reduces required inventories of spare parts, and also
simplifies removal and replacement procedures.
Removing the power supply from a rack will remove all DC voltages
from the rack that powers the CPM or EPM, and from all I/O modules
within the rack.
Removing power from the rack has the following consequences:
All control action stops
n
All power to all I/O modules in the rack is lost; hence, all control
n
outputs to the process are lost. Because external power connected
to terminal boards (from or to field devices) is still present, it is
essential that field devices are maintained in a safe condition
during replacement procedures.
Control to all I/O rack is lost.
n
Preventive Action(s)
Disconnect all signals at
terminal blocks from sources of
power before removing the
terminal block from the I/O
module.
Either: