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ADT490 TroubleShooting
Introduction to
Troubleshooting
Definition of “Trouble”
Trouble
a condition in which the fire alarm system
is operating in a degraded mode.
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Trouble
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Why is Troubleshooting
so important?
Troubles/problem that can worsen over time.
Examples: single ground fault turns into a double ground
Impact on Signal circuit
power failure
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Why is Troubleshooting
so important?
Central Station/Signal Receiving Operator’s view
minor or complete failure
Investigation of a Problem
urgent for life safety.
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Relevant Codes & Standards
What code or standard reflects the necessity for
troubleshooting?
The Fire Code clearly states
“building owner responsible maintaining fire alarm
system functionallity as
“the failure or malfunctioning of the appliance, device or
component would adversely affect fire or life safety”.
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Where Can Troubles Occur
1) Power supply
2) Input circuits
3) Output Circuits
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Where Can Troubles Occur
4) Device failure
A Beam Detector fully blocked will also cause a trouble
signal.
A mis-addressed detector gives Trouble and
“Unconfigured device”
5) Intentional (Disable or Bypass).
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What can the customer tell
us?
Owner, superintendent, or custodian.
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What can the customer tell
us?
Clues
o
“ This always happens a couple of days after it rains”.
o
“ The phone company was in a while ago or
cable guys were working on the 4th floor.”
o
“ The pool area has always been a problem
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What can the customer tell
us?
Ask questions:
o Have there been any contractors working in the building
in the past week or two?
what exactly were they doing and
where in the building were they working in?
o When did the trouble condition (or false alarm) occur?
o Have there been any complaints of leaks of any kind?
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Circuit Integrity Review
Any circuit features the Fire Alarm System needs:
1.
Metallic continuity
2.
No grounds
3.
No wire-to-wire shorts
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Circuit Integrity Review
Conventional-style Fire Alarm System,
small current through the circuit
the circuit opens and the current stops.
interruption of current detected
displayed as a Trouble condition.
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Circuit Integrity Review
Addressable-style Fire Alarm System,
digital communication between FACP and devices stops.
lack of response detected by the FACP
displays a trouble condition and
lists the missing device(s)
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Circuit Integrity Review
Often not obvious
disconnected or break.
Often connection to a device where the open or break occurs.
May be from
improper stripping - nick
or twisted too tightly under a wire nut (Marrette®).
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Circuit Integrity Review
Over-tightening screw can result in fracturing
May be some time later.
“opens” may be intermittent - repeated troubles.
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Circuit Integrity Review
Circuits must be free of grounds - both circuit conductors.
Circuits will tolerate a single ground
still operable
second ground on the other conductor
entire circuit will fail - shorted together
By common ground path ie steel junction box or EMT conduit.
FACP’s detect current increase to ground with a
ground-sensing circuit in the power supply.
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Circuit Integrity Review
In a conventional panel
a ground condition displayed as “System Trouble”
Recent panels a yellow LED ie “Ground” or “Earth” also lit.
Zone Trouble LED will not be lit – impact on current small
A ground, unlike an open, is not shown as a Zone trouble.
Same for a single ground on signal circuit.
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Circuit Integrity Review
A wire-to-wire short most dangerous of circuit troubles.
resistance is zero & voltage disappears.
In a signal circuit
a short renders the entire circuit inoperable
In an addressable input / output circuit
short -> all communication STOPS
system “crash”.
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Circuit Integrity Review
Only on a conventional Initiating circuit (and Sprinkler Supervisory
circuit)
short same as manual stations, heat detectors etc
circuit current will increase
FACP sees this as an alarm condition.
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Circuit Integrity Review
Wire-to-wire shorts are usually from
poor installation practices
stretching wire at conduit bends -> damage insulation
burr cuts through insulation and
provide a short between two conductors
wire-to-wire short same as a double ground condition.
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Faults to Trouble
1)
Open circuit – either on an input circuit or output circuit,
an open -> break in a conductor or
disconnection from a device.
In a conventional system -> loss of supervisory current
FACP and a trouble display (visual and audible) is created.
In addressable system
devices on a Data Communication Link (DCL)
beyond a break reported as missing
with visual and audible Trouble indication.
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Faults to Trouble
2)
Shorted circuit –> unable to support any voltage
Circuit current will increase.
Causes alarm if circuit conventional initiating.
conventional signal -> inoperable.
In an addressable system
DCL communication with the panel STOP.
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Faults to Trouble
3)
Ground – Devices on conventional circuits and addressable
DCL circuits
Required to work over a single ground condition.
Double ground same as a short from
to poor installation or water leaking into a device.
`FACP voltage on circuits “floats” above ground
creating a voltage between both “+ve” and “–ve” to earth
allows ground detection on both sides of the circuit.
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How do we know a
system is in Trouble?
1)
Audibly – a FACP trouble buzzer
manually silence-able by pressing “Panel Silence”,or
“Trouble Silence” etc.
Note:
Buzzer also used with sprinkler supervisory switch
accompanied Supervisory LED
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How do we know a
system is in Trouble?
2)
Visually – System Trouble or Common Trouble LED lit.
Look for another LED on.
Typically, only the green “AC On” LED should be lit.
Other LEDs may be hidden behind the front panel.
Some pulsing amber LEDs may be normal (i.e. communication)
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How do we know a
system is in Trouble?
3)
Remote from Signal Receiving Centre or
a call from the building owner or property manager.
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What tools will we use in
Troubleshooting routines?
1)
Eyes and Ears – Human Detection
Look for flashing LEDs on smoke detectors and Fault Isolators.
Determine if some devices still operate on Trouble.circuit
Carefully note
What indicators are on when you look at the FACP.
Look for messages on the Liquid Crystal Display (LCD).
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What tools will we use in
Troubleshooting routines?
2)
Logic
What happened immediately prior to the Trouble condition?
What contractors have been in the building?
Recent weather? i.e. rain, likely place for a wet ground?
Identify circuit in trouble with resistor substitution.
Boolean approach divides circuit in half.
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What tools will we use in
Troubleshooting routines?
3)
Analog or digital multi-meter
read circuit current, voltage, resistance, and
resistance to ground.
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What can the FACP tell us?
Study the FACP.
Determine if trouble is in one of 5 areas
Input,
Output,
Power,
Device trouble,
Bypass.
FACP give clue trouble is signal circuit or initiating circuit.
.
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Exercise - 1
AC
Z1 Alarm
Battery
Z1 Trouble
System
Alarm
System
Trouble
Bells are ringing,
a wiring break in Zone 3,
Batteries are weak,
MPS active in Zone 2
[B]
Alarm on Zone 3, open on Zone 2,
Emergency lights are on in FACP room
[C]
Pull station pulled on Zone 2,
power failure,
building is quiet,
open on Zone 3
[D]
FACP breaker has operated,
horn is missing,
open circuit and
single ground on Zone 3
[E]
Smoke detector operated on Zone 2,
no 115VAC for FACP,
wire has broken on Zone 3,
signals are operating.
Z2 Alarm
Z2 Trouble
Circuit
Z3 Alarm
Ground
Z3 Trouble
System
Silenced
Z4 Alarm
Bypass
[A]
Z4 Trouble
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Exercise - 2
AC
Z1 Alarm
Battery
Z1 Trouble
System
Alarm
System
Trouble
Power has been interrupted to the FACP,
A pull station is in alarm on Zone 4,
An open-circuit trouble on Zone 3,
building is quiet.
[B]
Double ground has on Zone 4,
emergency power is not grounded,
signals are operating,
main electrical feed to FACP is good.
[C]
Building is quiet
pull station has been operated on Zone 3
and a double ground has on Zone 4.
[D]
Zone 4 bypassed because it is grounded,
the building is silent,
emergency power is in open circuit trouble,
the main power feed is disconnected
E]
Temporal pattern is heard throughout,
zones 1-3 are disconnected from the FACP,
OS&Y active on Zone 4
Z2 Alarm
Z2 Trouble
Circuit
Z3 Alarm
Ground
Z3 Trouble
System
Silenced
Z4 Alarm
Bypass
[A]
Z4 Trouble
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Exercise - 3
AC
Z1 Alarm
Battery
Z1 Trouble
System
Alarm
System
Trouble
All power to FACP has failed,
Alarm on Zone 3,
Open circuit on Zone 1,
building is quiet.
[B]
Batteries are charging,
signals have failed,
Trouble on Zone 1,
Alarm on Zone 3
Z2 Alarm
Z2 Trouble
Circuit
Z3 Alarm
Ground
Z3 Trouble
System
Silenced
Z4 Alarm
Bypass
[A]
[C] AC is on,
battery fuse has failed,
heat detector is disconnected on Zone 1,
wire disconnected & grounded behind a bell.
[D] Ground on Zone 3,
open on battery connection,
short on Zone 1,
signals are operating.
[E]
No choices describe the correct scenario.
Z4 Trouble
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Device Failure
In conventional systems,
An internal electrical failure of a device will not cause a Trouble
condition, if integrity of the circuit is not affected.
A break in the coil winding of a bell,
disconnection of the blocking capacitor in a speaker,
corrosion of a switch in a manual station,
failure of a photo-receptor in a smoke detector
Device inoperable yet not cause a trouble condition.
Only caught during a regular, periodic inspection.
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Device Failure
Some devices can create a trouble signal on their own
these are primarily addressable analog devices
report individual condition like accumulated
dirt or environmental changes.
address not part of the programmed data base will make
generating a Trouble condition, and
displaying a message on the Liquid Crystal Display as
“unconfigured device”.
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Device Failure
Beam Detector
full blockage of the photo - receiver creating a Trouble
warning that it has been rendered inoperable.
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End
of
presentation