UFC 3 -430-11
14 February 2001
4-2.8
covered pushbuttons for shutdowns to guard against nuisance trips.
4-2.9
Plant Control Stations. Plant control stations, like panels, can be located
either in a main control room or locally. The main control room is the preferred locatio n.
Restrict local plant control stations to equipment that require them for start-up or
shutdown. In this case locate the control station as close to the equipment as practical.
A typical control station consists of a computer for processing and storing
data, a monitor, a keyboard, and a printer. Each of these items is discussed below.
4-2.9.1 Computers. Furnish the computer with a power supply that provides power
that is free of disturbances. The manufacturer should be able to provide power supply
specifications and recommend safeguards against severe power disturbances.
4-2.9.1.1 Control Limits. Limit the ability of the computer to control the plant to those
functions that can be safely controlled from the computer and in compliance with
applicable codes. Provide an alarm connected to an annunciator to show computer
malfunction.
4-2.9.1.2 Data Overflow Alarm. Provide computers that are used for logging data with
an alarm connected to an annunciator to show the following.
Data storage capacity is approaching full.
Data storage capacity has been exceeded.
4-2.9.1.3 Redundancy. Provide a spare computer to automatically take over the
logging of critical data in the event of primary computer malfunction.
4-2.9.2 Monitors. Cathode-ray tube (CRT) monitors are the most commonly used
type. Others include LCD type and luminous gas plasma screen type. Provide a spare
monitor that can be readily switched over to display critical data in the event that the
primary monitor malfunctions.
4-2.9.3 Keyboards. Provide sealed-type keyboards to resist liquid spills. Keyboards
can be either a standard type or a non-standard with specialized keys. Standard
keyboards should be used as much as practical. Mistakes are more likely to be made
using a non-standard keyboard than using a standard keyboard. Keyboard replacement
is also more difficult with a non-standard type.
4-2.9.4 Printers and Plotters. Provide an alarm connected to an annunciator to
show printer failure for printers receiving critical on-line data. Also provide a back-up
printer to take over if the primary printer malfunctions.
4-2.10
Data Logging. Provide the following minimum data logging for digital type
control systems. Print out this information automatically on a dedicated printer.
4-7
Previous Page
