UFC 3 -430-11
14 February 2001
Obtain the information from a control station read-out or from a monitor
whenever practical instead of using status lights fo r digital type control systems.
4-2.6
Annunciators. Annunciator standards are defined by ANSI/ISA-S18.1,
Annunciator Sequences and Specifications. Use common trouble alarms instead of
dedicated alarms as much as practical. Provide both visual and audible alarms. Provide
a dedicated alarm for critical items.
4-2.6.1 Common Alarms. Provide a dedicated window to contain the common
trouble alarms. When possible, include on this display the specific item within the group
that caused the alarm.
4-2.6.2 Dedicated Alarms. Provide a separate window that includes all dedicated
alarms associated with an area. Typical dedicated alarms are summarized in Table 6 -2 .
4-2.6.3 Annunciator Systems. Include the following minimum items in an
annunciator system.
Solid-state electronic system with first-out sequence.
Back-lighted windows.
Acknowledge, test, and reset pushbuttons. Locate the pushbuttons outside
of the annunciator cabinet so that the cabinet door does not have to be
opened to depress the pushbuttons. Provide a separate audible signal
device and separate pushbuttons for each annunciator system.
4-2.6.4 Alarm Indications. The alarm indication is controlled by the annunciator
manufacturer. Typical indications for various fault conditions follow.
Normal - Light off and audible alarm off
Abnormal - Light flashing, audible alarm on
Abnormal First Out - Same as above except flashing pattern is different to
distinguish it as a first out.
Acknowledge - Audible alarm off
Other than first-out - Light steady
First-out - Light flashing but pattern is different from prior to
acknowledgment
Return to Normal - Light off and audible alarm off
4-2.7
Selector Switches. Provide a minimum of SPDT contacts for selector
switches. Clearly label all switch positions. Label unused positions as such. Use back-
lighted switches for critical items in areas that are not well lit.
Momentary selector switches may be required to electrically sequence
equipment to start on emergency d iesel generator power following the loss of normal
power. This is necessary so as not to overload the emergency power circuit with
equipment that has selector switches maintained in the "Run" mode.
4-6
Previous Page
