SLAC Guidelines for Operations
22
Standards for Alarms, Warnings, and
Advisories
1. Introduction
The following standards have been adopted for indicator lights, monitor displays, and audible
signals used in accelerator, detector, and experimental facility control stations1.
2. Classification Levels
Informational signals are classified into three levels of severity: alarms, warnings, and
advisories. Policies governing the use and impairment or bypassing of these signals, including
approval processes and documentation requirements, are established by the organizations that
manage the corresponding response procedures2.
2.1 Alarms
An alarm is a signal indicating a condition posing an immediate threat to personnel safety or
environmental damage. An alarm may be presented at both the location of the threatening
condition and at a remote control station, and should be accompanied by an audible signal.
Alarms require immediate response, investigation, and resolution. A written response procedure
must be readily available at the control station for each alarm signal. Alarms should have
hardwired3 indicators, and should be located in panels separate from routine operating controls
and advisories. Information associated with the alarm, which may be necessary for diagnosing
the cause of the alarm, may be presented by a software-based system.
2.2 Warnings
A warning is a signal indicating a threat to equipment with a high degree of programmatic
importance4. This classification should be limited to conditions that pose a significant threat to
operational systems that meet minimum standards of high replacement cost and/or program
interruption time. A warning indicator should be accompanied by an audible signal. Warnings
require a prompt response (second to alarms), even if this requires shutting down an operational
system; however, the responding staff should exercise judgment in tailoring the response to the
particular conditions, and may choose to defer action if appropriate. Recommended response
1 A control station is defined as a location normally manned by trained operations staff for controlling the operation of one or more
facilities.
2 Bypassing or impairment of fire alarm systems or detectors is subject to policies and procedures established by the ES&H Division, as
documented in the SLAC ES&H Manual, Chapter 12, and other documents specified there.
3 Hardwired means that there is a direct electrical circuit between the source of the status information (excepting multiplexing devices
such as relays) and the panel indicator.
4 Specifically, this refers to circumstances in which a complete failure of the device or system concerned involves the possibility of
property loss exceeding $100,000 or an unplanned facility shutdown of one week or more.
November 26, 2008
SLAC-I-010-00100-000-R008
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SLAC Guidelines for Operations
procedures should be available at the control station for each warning signal. Warnings with
hardwired indicators should not share panels with Alarm indicators. Warnings may be generated
and presented through software-based control systems.
2.3 Advisories
An advisory is a signal indicating the status of less critical equipment. This classification
includes nearly all fault-indicating signals required for operations other than those that meet the
stringent definitions of alarms or warnings. An advisory typically indicates a component failure
or equipment operating outside tolerance limits. The corrective action may occur at a later time
according to best management practices. Responses to advisories should be coordinated with the
facility operations management.
This guideline was reviewed and approved by:
SLAC Director
P. Drell
ETS
L. Klaisner
LCLS
D. Knutson
Operations
A. Merola
Photon Science
K. Hodgson
PP&A
S. Kahn
SSRL
J. Stohr
November 26, 2008
SLAC-I-010-00100-000-R008
22, Page 2 of 2