Annunciator Alarm Systems Buyer`s Guide

Annunciator Alarm Systems
Buyer’s Guide
An easy-to-digest overview of common capabilities and features
of modular alarm annunciators
Excellence in Monitoring & Measurement for Over 55 Years
Table of Contents:
Click on link to navigate to desired location
Introduction and Focus …..…………………………………………………………………………………………………… 3
Size: Chassis type, Alarm Points and Dimensions ………………………………………………………………… 4
Networkable (communication) or Stand-alone (no communication) ………………………………….. 7
Software Configurability ……………………………………………………………………………………………………… 7
Event Recording ………………………………………………………………………………………………………………….. 7
Outputs ………………………………………………………………………………………………………………………………. 8
Field Contact Voltage ………………………………………………………………………………………………………….. 8
Source Voltage ……………………………………………………………………………………………………………………. 8
Display: LED and Window Lenses for Alarm Grouping ………………………………………………………… 8
Other Types of Annunciators ………………………….………………………………………………………………….. 9
Introduction and Focus
This Annunciator Alarm Systems Buyer’s Guide
aims to help in the initial research and
selection of an alarm annunciator for the
process control and power industries. In this
guide, an annunciator will be defined as a
device that is designed to alert operators of
abnormal process conditions (i.e. low/high
temperature alarms, pressure alarms, etc.) in
plant/refinery/process operations.
Annunciators can be found in control rooms,
boiler rooms, power substations or just about
any type of process or operational environment where conditions need to be personally monitored and
status indication is necessary.
This guide will only discuss integrated logic alarm annunciators - annunciators in which the alarm condition
and responsive operator actions are dictated by a programmed logic sequence. A sequence, by definition, is
“the chronological series of actions and states of an annunciator after an abnormal process condition or
manual test initiation occurs” (ISA–18.1–1979 (R2004), Annunciator Sequences and Specifications). Basically,
an annunciator alarm sequence defines the steps an operator would take in response to the alarm
condition. Most annunciators are standardly equipped with the ISA (International Society of Automation)
standard alarm sequences. Custom alarm sequences are often supplied by most manufacturers upon
customer request. See ISA–18.1–1979 (R2004), Annunciator Sequences and Specifications for more
detailed information on sequences. When choosing an annunciator, you need to determine which
sequence is most suitable for the process. It is important to note that some annunciators have software
programming capabilities which allow the sequence to be selected or changed in the field via computer.
If you are only looking for an alarm display that will provide a visual status without logic, then you will want
to direct your search to a “LED/lamp box” or “LED/lamp cabinet.” These types of alarm displays are driven
by other devices such as PLCs or remote logic annunciators. LED lamp boxes by themselves do not have the
function of flashing alarms or audible outputs. This guide will not discuss selection of LED/lamp boxes or
cabinets.
Let’s Begin…
The following sections are meant to guide you step-by-step through the features you should consider when
researching the suitable annunciator for your application.
Annunciator Alarm Systems Buyer's Guide | 3
Size: Chassis type, Alarm Points and Dimensions
Annunciators are sold in many different shapes and sizes but are typically modular in construction and
designed as module cells high by module cells wide. Several factors contribute to the system’s size,
dimensions and window display configuration. Those factors include:
1) The chassis needed for the installation
2) How many alarm points you need to monitor
3) The control panel, cabinet or field space you have available for the annunciator
1) Chassis
The best place to start is to determine which chassis is needed for the annunciator’s installation. The most
common types of annunciator chassis are panel-mount, surface-mount and rack-mount.
A panel-mount chassis (also referred to as flush-mount) is designed to be mounted in a panel cut-out,
typically in a control room type setting. Wiring can only be accessed from the back of the panel, therefore
leaving only the alarm display (with or without pushbuttons) showing in the front of the panel. Depth
dimensions of these panel-mount chassis can vary by manufacturer so it is important to request dimensions
and drawings to be sure that the system fits in your installation setting.
A surface-mount chassis is a cabinet-type enclosure whereby the alarm chassis is mounted on to a panel
inside an enclosure that provides front door access to the annunciator’s terminal wiring. This type of chassis
is suitable for applications where the annunciator system is to be in a NEMA or IP-type enclosure and
terminals must be accessed from the front of the annunciator system.
A rack-mount chassis is standardly manufactured in a 19” width and is designed to be slid into a vacant
space in a pre-existing rack. The 19” width limits the number of horizontal windows for the alarm display
but can be expanded vertically to accommodate the necessary amount of alarm points.
Note: Special applications may call for NEMA 1, 12, 4, 4X enclosures or purge systems.
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2) Alarm Points
Once you’ve selected the chassis type, then determine how many alarm points (or inputs) need to be
monitored in your operation or process. The amount of points will dictate how many module cells you will
need to display the alarm conditions. For example, if you need to monitor a high pressure level, low
pressure level, high temperature level and low temperature level, you will need four points. You’ll also
have to take into consideration how big you want the module cells and text legends to be and what will
provide the operator with the best level of awareness for your environment.
Example A: 2 module cells high x 2 module cells wide
(Each point occupies one full “cell” or “module” space)
HIGH
PRESSURE
LOW
PRESSURE
HIGH
TEMP
LOW
TEMP
Example B: 1 module cell high x 4 module cells wide
HIGH
PRESSURE
E
LOW
PRESSURE
HIGH
TEMP
LOW
TEMP
Example C: 1 module cell high x 2 module cells wide with 2 alarm points per module cell for a total of four
alarm windows
HIGH PRESSURE
LOW PRESSURE
HIGH TEMP
LOW TEMP
Note: Alarm points are typically configured left to right.
1
2
3
4
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Pushbuttons: The number of module cells you need will also depend on the desired location of the
pushbuttons. The three most common positions for the pushbuttons are either 1) occupying bottom right
module cell space 2) on the bottom right trim of the chassis or 3) located remotely. The standard is to have
the pushbuttons occupy the bottom right module cell. Below are two common examples of pushbutton
location. The most common pushbutton options are Test, Acknowledge, Silence and Reset. Manufacturers
may offer more pushbutton options (i.e. First Out Reset).
Example D: 4 point system with integral pushbuttons – 1 module cell high x 5 module cells wide
HIGH
PRESSURE
E
LOW
PRESSURE
HIGH
TEMP
LOW
TEMP
TEST
SIL
ACK
RES
Example E: 4 point system with pushbuttons on trim – 1 module cell high x 4 module cells wide
(Pushbuttons do not need to occupy one window space)
HIGH
PRESSURE
E
LOW
PRESSURE
HIGH
TEMP
LOW
TEMP
TEST
SIL
ACK
RES
3) The control panel, cabinet or field space you have available for the annunciator
The space that you have available for the annunciator is another large factor
in the construction of the system and how many alarm points you can fit per
module cell. For example, if you are limited by a 6” width cutout space but
need to monitor 20 points, you could build your module cells vertically and
divide each cell by 4 points.
Example F to right: 20 point system with pushbuttons on trim – 5 module
cells high x 1 module cell wide to accommodate limited cutout space in
control room
One module cell
split into four points
for a total of 20
windows (20 points)
for the entire system
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
6
Networkable (communication) or Stand-Alone (no communication)
Built-in Ethernet capability allows for communication between your annunciator
system and plant control systems such as PLCs or other field instrumentation
devices. There are a variety of network protocols (i.e. Modbus/TCP, DNP3, etc.)
that can be used. You must decide if Ethernet communication is needed or
desired, as well as make sure the annunciator you purchase has the proper
protocols needed for your network.
Ethernet communication also allows for features such as remote monitoring
with annunciators or remote HMI displays, as well as distributed network
connection with other Ethernet devices.
Communication may not be desired or necessary. Some plants and companies
prefer to keep their alarm systems as stand-alone (no communication) systems
in an effort to protect their critical alarms from cyber network vulnerabilities.
Software Configurability
If you are seeking the ability to re-configure the annunciator features via
computer or laptop in the field, you will need an annunciator with software
configurability done through network or serial communication.
WARNING:
It is important to note that
the use of network
communication comes with
the risk of vulnerability to
cyber hackers. Should you
select an annunciator that
requires network
connectivity, it is important
to either 1) make sure your
annunciator network is
isolated from your
operation’s main control
network or 2) set up secure
firewalls to help safeguard
yourself from cyber hacking.
Event Recording
Annunciators with event recording capabilities can provide the operator with information about each alarm
event such as: time of alarm (time-tagging), order of alarms, time of acknowledgement and more. The
ability to time-tag alarm events to the nearest millisecond has become a popular feature in modern
annunciator systems.
Depending on your alarm needs, this may or may not be a necessary feature.
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Outputs
Annunciators can be supplied with relay outputs and/or transistor outputs. Depending on the
manufacturer, some relay outputs are standard while others are optional. Make sure the annunciator you
choose has the necessary outputs you need for your operation.
Common relay outputs include:





Audible and visual signals: horn, beacon, bell
Common Trouble Alarm (CTA) Relay: notification of any alarm within the system (commonly used
for remote beacon or dial-up)
Group CTA functions: for critical and noncritical groups
Auxiliary Contact Repeat Relay: individual repeater output per input
Reflash Alarm Relay: alarm counter
Other relays may include: Diagnostic Relay, Ringback Relay, Loss of Power Relay, etc.
For equipment needing under 24 volt inputs, transistor outputs of the annunciator are used.
Field Contact Voltage
Annunciators are standardly capable of accepting a wide range of DC or AC field contact voltages (dry or
live contacts).
Source Voltage
Annunciators are standardly capable of accepting a wide range of DC or AC source voltages with integral or
external power supplies.
Display: LED and Window Lenses for Alarm Grouping
Colored framing (or bezels) and colored cell filters or lenses allow for clustering or grouping of alarm
functions. For example, if you have a set of temperature alarms that you want to separate from the rest of
your alarms, you could put a yellow lens or filter on those windows with red framing (or bezels) to
differentiate them from the rest.
Example G: Grouping of four temperature alarms with red framing and yellow lens
TEMP
POINT
TEMP
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
TEMP
POINT
TEMP
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
TEST
SIL
ALARM
POINT
ALARM
POINT
ALARM
POINT
ALARM
POINT
ACK
RESET
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It is now standard for annunciators to utilize LED lights for window illumination. Some manufacturers may
still provide lamp bulb lighting, but LEDs have proven to be the most preferable, sustainable and economic
option. White LEDs are a common option, however, if you prefer different color illumination, check with
your manufacturer to make sure the desired color is available.
If you need colored lenses, framing or LEDs, be sure to make your manufacturer aware of this. Some
manufacturers have a standard of all white windows and LEDs with black module cell framing.
Other Types of Annunciators
There are several other types of annunciators that have not been listed in this guide. For a more detailed
explanation of the following annunciators, feel free to contact Ronan Engineering.
Split architecture annunciator
Split-architecture annunciators separate the display from the electronics containing the alarm logic,
allowing the display to be a remote distance (range varies by manufacturer) away from the actual
annunciator. This is a common option for reduced weight systems and applications with limited space for
display.
Explosion-proof annunciator
Explosion-proof Annunciators are designed for hazardous locations. They provide maximum flexibility for
use under specified operating conditions approved for National Electric Code Hazardous Locations such as:




Class 1 Division 1, Groups B, C & D
Class II, Division 1, Groups E,F, G
Class III, Divisions 1 and 2
NEMA 7 C, D; NEMA 9 E, F, G
Sequence of Events Recorder
A Sequence of Events Recorder (SER) is a standalone microprocessor based system that typically monitors a
high volume of inputs and records the time and sequence of alarm events. SERS are a helpful diagnostic
tool for troubleshooting to minimize operational downtime. Redundant SER systems are often used in the
nuclear and power industries as a back-up system for conventional PLC-based SCADA alarm systems.
Relay logic annunciators
Although relay logic-based annunciators utilize traditional relay contact technology, they continue to be a
viable and widely used option for many plants.
Relay annunciators do tend to be more costly due to the dedicated relays and wiring in the annunciator.
The combination of proven reliability, noise immunity and simplicity of the logic circuits makes the relay
systems ideally suited for oil platforms, desert or arctic environments, shipboard or any place with limited
access to technical support.
Annunciator Alarm Systems Buyer's Guide | 9
Thank you for reading the Annunciator Alarm
Systems Buyer’s Guide.
Finding and selecting the right annunciator to meet your specifications can be cumbersome without a
roadmap. We hope that this guide will be a helpful resource as you continue your research and select the
best product for your project requirements.
If you have any questions about the steps or features discussed in this guide, feel free to contact Ronan
Engineering Company.
Excellence in Monitoring & Measurement for Over 55 Years
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